Microsoft Word - 04-Postural Control Strategies on Smart Phone use during Gait in Over 50-year-old Adults

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1 KJSB Korean Journal of Sport Biomechanics 2019; 29(2): eissn ORIGINAL Postural Control Strategies on Smart Phone use during Gait in Over 50-year-old Adults 50 세이상성인의보행시스마트폰사용에따른자세조절전략 Yeon Joo Yu 1, Ki Kwang Lee 2, Jung Ho Lee 3, Suk Bum Kim 4 1 Department of Sports and Health Sciences, Sangmyung University, Seoul, South Korea 2 Department of Sports Health and Rehabilitation, Kookmin University, Seoul, South Korea 3 K2 Korea Co., Seoul, South Korea 4 Department of Rehabilitation Personal Training, Konyang University, Nonsan, South Korea Received : 03 June 2019 Revised : 18 June 2019 Accepted : 18 June 2019 Corresponding Author Suk Bum Kim Department of Rehabilitation Personal Training, Konyang University, 121 Daehak-ro, Nonsan, Chungnam, 32992, South Korea Tel : Fax : bum3340@kongyang.ac.kr Objective: The aim of this study was to investigate postural control strategies on smart phone use during gait in over 50-year-old adults. Method: 8 elderly subjects (age: 55.5±3.29 yrs, height: ±4.20 cm, weight: 62.87±8.44 kg) and 10 young subjects (age: 23.8±3.19 yrs, height: 158.8±5.97 cm, weight: 53.6±5.6 kg) participated in the study. They walked at a comfortable pace in a gaitway of ~8 m while: 1) reading text on a smart phone, 2) typing text on a smart phone, or 3) walking without the use of a phone. Gait parameters and kinematic data were evaluated using a three-dimensional movement analysis system. Results: The participants read or wrote text messages they walked with: slower speed; lesser stride length and step width; greater flexion range of motion of the head; more flexion of the thorax in comparison with normal walking. Conclusion: Texting or reading message on a smart phone while walking may pose an additional risk to pedestrians' safety. Keywords: Gait, Smart phone, Dual-task, Aging INTRODUCTION 2017년인터넷이용실태조사에따르면만3세이상인구중스마트폰이용자의비율은 87.8% 를차지하며, 50대의 97.1%, 60대의 79.6%, 70대의 29.8% 가최근 1개월내스마트폰을통해무선인터넷을이용하였다. 통계청이발표한 '2017 한국의사회지표발표 ' 는우리나라국민들의과도한스마트폰이용으로스마트폰에대한현저성증가, 이용조절능력이감소하여문제적결과를경험하는상태인스마트폰과의존율은 2016년보다 0.8% 증가하였고, 청소년의과의존율은감소한반면 50대 14.1%, 60대 12.9% 로과의존율은증가하고있음을보고하였다. 이렇듯우리의생활속깊숙이들어온스마트폰은연령에상관없이일상생활움직임동작과함께이용되고있다. 보행시스마트폰을사용하여문장쓰기 (Typing text), 문장읽기 (Reading text) 과제수행시인지적요구는증가되며, 이는우리몸의기억장치와수행조절력에영향을준다 (Rubinstein, Meyer, & Evans, 2001). 주위를둘러싼환경에대한시각적인정보가줄어들거나, 스마트폰을들고있는보행자의안정된자세유지와보행움직임을구축하기위해움직임의신체적또는기계적인변화가요구된다 (Schabrun, van den Hoorn, Moorcroft, Greenland, & Hodges, 2014). 보행시스마트폰을이용하여문장쓰기과제를수행할때보행하며스마트폰으 Copyright C 2019 Korean Journal of Sport Biomechanics This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

2 72 Yeon Joo Yu, et al. KJSB Table 1. Physical Characteristics of subjects and information of smart phone use Characteristics Young group (n=10) Old group (n=8) Age (yrs) 23.8± ±3.29 Weight (kg) 53.6± ±8.44 Height (cm) 158.8± ±4.20 Dominant hand: right: left: both Right (9), left (1) Right (7), left (1) Typing method: one hand: both hands: alternately Both hands (10) One hand (6), both hands (1), alternately (1) Phone direction: vertical: horizontal Vertical (10) Horizontal (8) Smart phone type: i-phone: Samsung: LG: etc Samsung (4), i-phone (4) LG (1), etc (1) Samsung (6), LG (2) How many months did you use smart phone you are using now? 10.8±8.5 (months) 16.57±12.75 (months) How many minutes do you call with your smart phone? 27.2±21.74 (minutes) 23.75±18.46 (minutes) How many minutes do you send a message or SNS with your smart phone? min: 60 (minutes) max: all day long min: 10 (minutes) max: 90 (minutes) Number of Subject who have an accident while send a message with smart phone 0 0 로통화하기 (Lamberg & Muratori, 2012) 또는보행하며스마트폰의문장읽기과제수행시 (Schabrun et al., 2014) 보다보행속도는크게줄어들었고, 발의수행방향이측면으로많이기울어졌음이보고되었다. 젊은이를대상으로횡단보도보행과동시에스마트폰화면에나타나는질문을읽고, 질문에대한답을찾기위해인터넷브라우저에단어를입력한후화면에나오는결과를다시 SNS에입력하는과제가수행되었는데 (Yu, Kim, & Kong, 2016), 스마트폰사용과제를성공적으로수행하고정해진시간안에횡단보도를건너기위해선시각정보와인지정보의적절한분배가필요함이확인되었다. Shin, Jang, Jang, & Park (2013) 은가만히선자세로첫수행에서는 100부터 3씩뺀숫자말하기, 두번째수행에서는 100 부터 7씩뺀숫자말하기과제를노인들이행할때수동적이고제한된움직임패턴을보였다고보고하였다. 65세이상노인은저하된균형력에따른안정성확보를위해젊은이에비해감소된보행속도, 한발지지기를길게유지하는전략을사용하여걷는것으로나타났다 (Yi & Chang, 2014). 학습효과가없는인지과제를수행하며트레이드밀위에서걷는이중과제도인지과제와보행움직임에영향을주는것으로나타났다 (Choi, Kang, & Tack, 2008). 더욱이보행을하며인터넷브라우저를사용하는과제는읽기와쓰기가여러번반복된과제이기에보행자의집중을방해하는시각정보, 인지정보를분리및단순화하여완성된다. 따라서각각의과제가보행움직임에어떤영향을주는가에대한궁금증이있다. 또한스마트폰사용에따른보행의특성을분석한선행연구들은젊은이를대상자로한정지었으나, 스마트폰의대중화로인해 50세이상중 장년층의스마트폰사용률도높기에 50세이상성인들의스마트폰사용에따른보행의특성을분석하는것도필요하다. 따라서본연구의목적은 50세이상성인의보행수행시스마트폰을이용하여문장쓰기, 문장읽기과제가보행동작에미치는영향을운동학적으로분석하는것이다. 20대젊은이들을비교집단으로선정하여 50세이상성인의보행시스마트폰이용에따른보행특성과비교 분석하였다. METHOD 1. 대상자 본연구에참여한실험집단은 50세이상여성 8명, 통제집단은 20대여성 10명이다. 두집단의대상자들은적어도 2개월전부터사용한스마트폰을소지하고있으며, 보행검사를위해하지관절에통증및정형외과적신체장애가없는자들로한정하였다. 대상자의신체적특성과스마트폰사용습관은 Table 1과같다. Korean Journal of Sport Biomechanics

3 KJSB Postural Control Strategies on Smart Phone use during Gait in Over 50-year-old Adults 측정방법 1) 실험도구실험은 10대의 3차원동작분석카메라 ((MX-T40, Vicon Inc, UK), 200 Hz) 가설치된 8 m 주로 (Gait way) 에서진행되었다. 카메라는적외선파장을이용해대상자신체에부착된마커의위치를감지하고, 이자료는다시카메라로보내져동작분석통합시스템 (Vicon MX Giganet) 을통해디지털신호로전환된다. 2) 실험절차실험대상자에게실험의목적, 실험과제를설명한후대상자의참여의사를확인하고, 실험동의서에서명을받았다. 대상자의신체적특성과스마트폰사용습관을조사하였다. 실험의편의를위해대상자는반팔과반바지를착용하고평소본인의걸음걸이를구현하기위해자신의운동화를착용하였다. 운동학적자료를얻기위해대상자의관절및분절 ( 머리 (Forehead, R/L head, Chin), 팔 (R/L upper arm, R/L medial elbow, R/L later elbow, R/L medial wrist, R/L later wrist, hand), 몸통 (R/L Shoulder, Trunk), 골반 (sacrum, R/L ASIS, R/L LIAC, R/L GT), 다리 (R/L thigh R/L medial knee, R/L later knee, R/L shank, R/L medial ankle, R/L later ankle, 발 (R/L META5, R/L Styloid, R/L cunniform) 에마커를부착하였고, 운동화겉면의발뒤꿈치중심부와첫번째중족골경부에마커를부착하였다. 세가지실험과제는다음과같다. 첫번째과제는스마트폰화면에나타난문장의내용을읽으며편안한속도로걷는것이다 (Reading Gait). 연구자가실험대상자에게스크롤을사용하지않을분량의내용 ( 시한편 ) 을실험전문자로보냈고, 대상자는보행을진행하며소리내어시를읽었다. 두번째과제는스마트폰을사용하여다음의문장 ( 나는지금 대에서실험실에참여하고있습니다.) 을문자메시지에입력하며편안한속도로걷는것이다 (Texting Gait). 문자입력시스마트폰의기능인문자자동입력기능을사용하지못하도록실험전조치하였다. 출발시대상자는문자메시지창을열고준비하였으며, 보행출발지시가떨어지면문자메시지창에문자를 Table 2. Gait parameters (mean ± s.d.) Variables Reading gait Texting gait Normal gait Statistical results Step time (s) Stride length Step width (cm) Step length Lateral variation of foot (cm) Gait speed (m/s) Cadence (step/min) Young 0.53± ± ±0.04 Gait Old 0.57± ± ±0.02 Gait Young 1.21± ± ±0.12 Gait Old 1.16± ± ±0.10 Gait Young 13.02± ± ±0.10 Gait Gait Old 12.16± ± ±0.15 Post-hoc Young 0.59± ± ±0.07 Gait Old 0.58± ± ±0.05 Gait Young 3.39± ± ±5.89 Gait Old 0.24± ± ±4.89 Gait Young 1.11± ± ±0.17 Gait Old 1.01± ± ±0.12 Gait Young ± ± ±8.63 Gait Old ± ± ±5.38 Gait F=27.746, p=.000 F=.400, p=.536 F=5.609, p=.008 F=63.913, p=.000 F=.000, p=.991 F=3.298, p=.050 F=16.943, p=.000 F= , p=.000 F=3.254, p=.052 2, 3 F=59.857, p=.000 F=.001, p=.978 F=4.282, p=.023 F=2.642, p=.087 F=1.872, p=.190 F=.253, p=.778 F=58.502, p=.000 F=.005, p=.946 F=5.863, p=.007 F=31.83, p=.000 F=.053, p=.820 F=6.433, p=.004 Note. Post-hoc sig. Reading gait - Texting gait: 1, Texting gait - Normal gait: 2, Normal gait - Reading gait: 3.

4 74 Yeon Joo Yu, et al. KJSB 입력하도록하였고, 주로가끝나는지점에서연구자가대상자의문자메시지창을확인하였다. 세번째과제는스마트폰을사용하지않고편안한보행을수행하는것이다 (Normal-Gait) (Schabrun et al., 2014). 대상자들이실험실주로와과제에익숙해지도록데이터수집전각과제당 3번의연습기회를부여하였다. 과제시작은연구자의언어지시로시작하였으며, 8 m 주로가시작하는출발지점에서과제를시작하였다. 대상자들은세가지과제를각각 5회씩수행하였으며, 과제수행은무작위순서로진행되었다. 3. 자료처리영상분석장비를사용하여얻은자료는 NEXUS 프로그램을이용하여 butterworth fourth filter 를사용하였고, cut off frequency 4 Hz로실시하였다. 보행분석구간은보행시작후약 2 m 지점에서오른쪽발의첫번째뒤꿈치착지부터동일한발의두번째뒤꿈치착지까지이다. 보행변인은다음과같이계산하였다. 보폭 (Step length) 은오른쪽발의발뒤꿈치가지면에닿는순간의수평위치로부터따라가는왼발의발뒤꿈치의수평위치사이의차이로계산하였고, 대상자의하지장으로나누었다. 보폭시간 (Step time) 은오른쪽발의발뒤꿈치가지면에닿는순간의수평위치에서의시간부터따라가는왼발의발뒤꿈치의수평위치에서의시간차이로계산하였다. 활보장 (Stride length) 은오른발 ( 지면을먼저딛는발 ) 이두번연속적으로이동한거리이며, 대상자의하지장으로나누었다. 보간 (Step width) 은오른발의내 외측좌표와뒤따라가는왼발의내 외측좌표사이의거리이다. 보행속도 (Crossing gait speed) 는보행시작후약 2 m 구간에서대상자의상후장골극의수평움직임으로계산하였다. 운동학적변인으로고관절, 무릎, 발목, 머리와몸통의각도가계산되었다. 보행시발의움직임을더자세히관찰하기위해발의외측편차를구하였다. 발의외측편차는활보장에서처음오른발과두번째로디딘오른발의뒤꿈치마커를선으로연결하여발의측면위치의변화를나타낸다 (Schabrun et Table 3. Head and trunk movement in anterior and posterior axis (mean ± s.d.) (unit: degree) Variables Reading gait Texting gait Normal gait Statistical results Young -2.55± ± ±10.43 Gait Old 8.42± ± ±8.94 Gait F= , p=.00 F=1.557, p=.230 F=3.946, p=.029 Head Young -6.69± ± ±11.11 Gait Gait Old 4.57± ± ±8.32 Post-hoc F=79.017, p=.000 F=2.092, p=.167 F=2.961, p=.066 2, 3 Young 4.84± ± ±3.61 Gait Gait Old 3.85± ± ±2.90 Post-hoc F=6.701, p=.004 F=1.325, p=.267 F=.800, p= Young -1.32± ± ±2.60 Gait Gait Old -4.64± ± ±3.19 Post-hoc F=7.964, p=.002 F=4.863, p=.042 F=2.905, p= Trunk Young -5.42± ± ±2.84 Gait Old -9.28± ± ±2.75 Gait F=3.823, p=.032 F=5.661, p=.030 F=2.464, p=.101 Young 4.10± ± ±1.29 Gait Old 4.63± ± ±1.75 Gait F=2.516, p=.097 F=.370, p=.551 F=.357, p=.702 Note 1. Post-hoc sig. Reading gait - Texting gait: 1, Texting gait - Normal gait: 2, Normal gait - Reading gait: 3. Note 2. Angle def. - Head: Related to Trunk vertical axis, Forward tilt (-), Backward tilt (+) Trunk: Related to Pelvis vertical axis, Forward tilt (-), Backward tilt (+) Korean Journal of Sport Biomechanics

5 KJSB Postural Control Strategies on Smart Phone use during Gait in Over 50-year-old Adults 75 al., 2014). 4. 통계분석본연구는 50대성인과 20대성인의보행수행시스마트폰을이용하여문장쓰기, 문장읽기과제가보행동작에미치는영향을비교 분석하는것이다. 반복측정이원배치분산분석 ( 두집단 (50대그룹 & 20대그룹 )*( 세가지보행과제 (Reading Gait, Texting Gait, & Normal Gait)) 을실시하였고, 변인들간유의한차이가나타나면사후분석으로 Scheffee 를사용하였다. 통계분석프로그램으로 SPSS 18.0을사용하였으며, p<.05로설정하였다. RESULTS 1. 보행변인 Table 2는보행과제수행시시 공간변인의결과를나타낸다. 보폭시간 (F=5.609, p=.008), 보폭 (F=4.282, p=.023), 보행속도 (F=5.863, p=.007), 그리고 cadence (F=6.433, p=.004) 변 Table 4. Hip, knee, ankle movement in anterior and posterior axis (unit: degree) Variables Reading gait Texting gait Normal gait Statistical results Young 28.23± ± ±5.43 Gait Old 30.95± ± ±4.48 Gait F=14.963, p=.000 F=1.332, p=.265 F=1.048, p=.362 Hip Young ± ± ±4.57 Gait Old ± ± ±5.68 Gait F=8.215, p=.001 F=.056, p=.816 F=1.708, p=.197 Young 43.76± ± ±3.75 Gait Gait Old 44.48± ± ±5.05 Post-hoc F=40.247, p=.000 F=1.886, p=.189 F=2.924, p=.068 2, 3 Young 58.47± ± ±5.38 Gait Old 61.42± ± ±6.48 Gait F=.922, p=.408 F=2.578, p=.128 F=1.376, p=.267 Knee Young -3.03± ± ±3.94 Gait Old 1.18± ± ±5.33 Gait F==.688, p=.510 F=3.760, p=.070 F=.372, p=.692 Young 61.50± ± ±4.58 Gait Old 60.24± ± ±2.19 Gait F=1.328, p=.279 F=.018, p=.895 F=.423, p=.659 Young 17.83± ± ±5.20 Gait Old 23.52± ± ±3.81 Gait F=17.565, p=.000 F=7.193, p=.016 F=1.605, p=.217 Ankle Young ± ± ±4.38 Gait Old -4.27± ± ±7.02 Gait F=16.492, p=.000 F=7.688, p=.014 F=3.333, p=.048 Young 29.77± ± ±6.33 Gait Old 27.80± ± ±4.468 Gait F=.717, p=.496 F=.028, p=.869 F=1.413, p=.258 Note 1. Post hoc sig. Reading gait - Texting gait: 1, Texting gait - Normal gait: 2, Normal gait - Reading gait: 3. Note 2. Angle def. - Hip: Related to Pelvis vertical axis, Flexion (+), Extension (-) Knee: Related to Thigh vertical axis, Flexion (+), Extension (-) Ankle: Related to Shank vertical axis, Dorsi-flexion (+), Plantar-flexion (-)

6 76 Yeon Joo Yu, et al. KJSB 인에서그룹과보행과제사이에교호작용이존재하는것으로나타났다. 활보장은보행과제간유의한차이가있는것으로나타났다 (F=63.913, p=.000). 보간은보행과제 (F=16.943, p=.000), 그룹 (F= , p=.000) 에서유의한차이가나타났다. 20대그룹이각각의보행과제에서 50대그룹보다보간이크게나타났다. 유의한차이가나타난보간변인의사후검정결과, 문장읽기보행과일반보행, 문장쓰기보행과일반보행의평균값에서유의한차이가나타났다. 2. 관절각도변인 Table 3에서제시하는관절의각도는전 후축방향의움직임을나타낸다. 머리움직임의최대각에서 (F=3.946, p=.029) 그룹과보행과제사이에교호작용이존재한다. 머리의최소각 (F=79.017, p=.000) 과가동범위 (F=6.701, p=.004), 몸통의최대각 (F=7.964, p=.002) 은보행과제간유의한차이가나타났다. 몸통움직임의최소각은또한그룹간 (F=5.661, p=.030), 보행과제간 (F=3.823, p=.032) 통계적으로유의한차이가나타났다. 고관절의최대각 (F=14.963, p=.000), 고관절의최소각 (F= 8.215, p=.001), 가동범위 (F=40.247, p=.000) 는보행과제에서통계적으로유의한차이를나타냈다 (Table 4). 발목관절의움직임시최대값은보행과제간 (F=17.565, p=.000), 그룹간 (F=7.193, p=.016) 통계적으로유의한차이를나타냈다. 발목관절의최소각은그룹과보행과제사이에교호작용이나타났다 (F=3.333, p=.048). DISCUSSION 본연구의목적은 50세이상성인의보행수행시스마트폰을이용하여문장쓰기, 문장읽기과제가보행동작에미치는영향을운동학적으로분석하는것이다. 보행시간, 보행속도, 시간당보폭수에서그룹과과제간교호작용이나타났는데, 각그룹이문장읽기과제와문장쓰기과제에서동일한패턴을보이는반면일반보행과제에서는상이한패턴을보였다. 스마트폰을이용한문장쓰기와문장읽기과제수행이보행움직임에영향을주는것으로생각된다. 본연구결과에서보행변수들중보간과활보장만이과제간유의한차이를보였기에, 스마트폰을사용하여문장읽기와문장쓰기과제간의명확한차이를이야기하기는어려우나, 대상자들은문장쓰기과제수행시활보장, 보폭, 외측편차가짧았고, 보폭시간과보행속도는느리고시간당보폭수의수는작게나타났다. 이러한결과는문장쓰기과제시보행속도의감소를보고한 Lamberg & Muratori (2012) 와 Schabrun et al. (2014), 스마트폰을이용하여전자메일보내기과제수행시보행속도와보간의감소를보고한 Demura & Uchiyama (2009) 의결과와일치한다. 보행시스마트폰을사용한문장쓰기동작은, 보다적은범위의문장읽기동작을포함하여, 보행의질을떨어뜨린다. Schabrun 등 (2014) 은연구에참여한대상자들의 35% 가보행중스마트폰에문장을쓰다가사고를당한경험이있다고보고하였다. 이러한결과는보행자가길을건너거나보행시장애물을만나는것이안전과연관되듯보행중스마트폰에문장쓰기동작또한보행자의안전을위협하는요소가될수있을것으로조심스레추측해본다. 일반보행시머리의전 후측방향의가동범위가큰반면문장쓰기와문장읽기과제수행시머리의가동범위는유의하게작게나타났다. 특히문장쓰기과제를수행하며보행시일반보행시보다머리의움직임이유의하게작게나타났는데, 문장쓰기동작은읽기동작보다더집중적인시각과손의움직임이필요한이중과제이기에머리의가동범위가작게나타난것으로해석된다. Schabrun et al. (2014) 에따르면머리는측면굴곡과회전방향의움직임을제외하고는흉곽과조화롭게움직인다. 머리는흉곽에구속되는형식으로연결되고, 눈, 몸통, 팔그리고스마트폰사이의관계를가장최적화시키는형식으로작동된다. 본연구에서일반보행보다스마트폰을사용하며문장읽기, 문장쓰기과제수행시몸통을유의하게굴곡시키는것으로나타났으며, 특히문장읽기과제수행시일반보행시보다몸통을더많이굴곡하며걸었다. 이는 20대대상자들이인터넷브라우저를사용하며횡단보도구간을건널때일반보행보다몸통과머리를깊숙이숙이며걷는결과와일치한다 (Yu et al., 2016). 본연구에선 50대그룹이 20대그룹에비해몸을더많이굴곡시켜스마트폰을이용하여문장을읽고, 문장을쓰는것으로나타났다. 스마트폰을사용하며걷는보행은보행의기능적인역할을손상시키고보행자의안전을위협한다. 제한된보행패턴, 느린보행속도, 보행시이중과제의수행은낙상의위험요소를더크게만든다 (Woollacott & Shumway-Cook, 2002). 이중과제수행과더불어노화로인한신체적안정성의저하또한보행패턴에영향을미치는것으로생각된다. 이중과제수행시우리뇌의인지영역에서는과제선정에대한경쟁이일어나며한가지과제가먼저정해지고수행된다. 건강한사람들의경우이중과제 ( 인지과제 & 보행과제 ) 수행시인지과제보다는보행의안정성을우선하는전략을사용한다는이론이지배적이었으나 (Shumway-Cook, Woollacott, Kerns, & Baldwin, 1997). 자세보유, 위험감지, 그리고과제복잡성에대한능숙함에근거하여인지과제가선점된후수행된다고보고되기도하였다 (Schabrun et al., 2014). 건강한이들이움직임시충분한안정성을확보하고있다면, 보행의안정성보다는인지과제를먼저수행하기도한다 (Yogev-Seligmann, Korean Journal of Sport Biomechanics

7 KJSB Postural Control Strategies on Smart Phone use during Gait in Over 50-year-old Adults 77 Hausdorff, & Giladi, 2012). 그러나실제보행시예상치못한보행환경에직면할수도있고, 이중과제를행하는개인의능력에따라결과는달라질수있을것이다. 따라서추후연구로대상자개인의이중과제능력, 스마트폰사용시보행의움직임과사고경험등의관계를밝히는것도필요하다. CONCLUSION 본연구는 50세이상성인의보행수행시스마트폰을이용하여문장쓰기, 문장읽기과제가보행동작에미치는영향을운동학적으로분석하였다. 스마트폰을사용하며걷는동작은두과제를동시에수행하는이중과제로인지력의분배가요구되고주위환경을보는시각의배제가발생하기에, 느린보행속도, 보간의감소, 머리움직임의감소, 몸통굴곡의증가등일반보행과는상이한보행의특성을나타냈다. 이렇듯변화된보행변인은스마트폰을이용하여문장쓰기와문장읽기를행하는보행자의안전에큰영향을줄것이다. ACKNOWLEDGEMENT This work was supported by the istry of Education of the Republic of Korea and the National Research Foundation of Korea (NRF-2016S1A5B5A ). REFERENCES 2017 Survey on the internet usage. (2018), Korea Internet & Security Agency Social indicator in Korea. (2018), Statistics Korea. Choi, J. S., Kang, D. W. & Tack, G. R. (2008). Effects of walking speeds and cognitive task on gait variability. Korean Journal of Sport Biomechanics, 18(2), Demura, S. & Uchiyama, M. (2009). Influence of cell phone use on characteristics of gait. European Journal of Sport Science, 9, Lamberg, E. M. & Muratori, L. M. (2012). Cell phones change the way we walk. Gait and Posture, 35(4), Rubinstein, J. S., Meyer, D. E. & Evans, J. E. (2001). Executive control of cognitive processes in task switching. Journal of experimental psychology. Human Perception and Performance, 27(4), Schabrun, S. M., van den Hoorn, W., Moorcroft, A., Greenland, C. & Hodges, P. W. (2014). Texting and walking: strategies for postural control and implications for safety. PLoS One, 9(1), e doi: /journal.pone ecollection Shin, S. H., Jang, D. G., Jang, J. K. & Park, S. H. (2013). The effect of age and dual task to human postural control. Korean Journal of Sport Biomechanics, 23(2), Shumway-Cook, A., Woollacott, M., Kerns, K. A. & Baldwin, M. (1997). The effects of two types of cognitive tasks on posture stability in older adults with and without a history of falls. Journals of Gerontology Series a-biological Sciences and Medical Sciences, 52, M232-M240. Yi, J. H. & Chang, J. K. (2014). The comparative analysis of gait safety between elderly female and adult female. Korean Journal of Sport Biomechanics, 24(3), Yogev-Seligmann, G., Hausdorff, J. M. & Giladi, N. (2012). Do we always prioritize balance when walking? Towards an integrated model of task prioritization. Movement Disorders, 27, Yu, Y. J., Kim, S. B. & Kong, S. J. (2016). Effects of smartphone use on pedestrian crossing. Kinesiology, 18(2), Woollacott, M. & Shumway-Cook, A. (2002). Attention and the control of posture and gait: a review of an emerging area of research. Gait and Posture, 16,

Kinematic analysis of success strategy of YANG Hak Seon technique Joo-Ho Song 1, Jong-Hoon Park 2, & Jin-Sun Kim 3 * 1 Korea Institute of Sport Scienc

Kinematic analysis of success strategy of technique JooHo Song 1, JongHoon Park 2, & JinSun Kim 3 * 1 Korea Institute of Sport Science, 2 Catholic Kwandong University, 3 Yonsei University [Purpose] [Methods]