조립 형태 인솔의 경도 변화가 달리기의 충격 흡수 기능과 착화감에 미치는 영향

류시현(Sihyun Ryu),박상균(Sang-Kyoon Park) 대한인간공학회 2020 大韓人間工學會誌 Vol.39 No.6

Objective: The purpose of the study was to investigate the effects of assembling insole hardness (basic insole, [BI], hard hardness insole, [HI], medium hardness insole, [MI], and low hardness insole, [LI]) on the impact variables and the comfort during running. Background: Foot size and shape vary according to gender and age, and the preferred cushioning varies each person. Therefore, an assembly type insole with different hardness is required depending on the functions of each plantar position. Method: Twenty healthy male adults (age: 22.7±1.8 years, body weight: 72.5±7.7kg, height: 175.3±4.3cm) participated in this study. The data was collected during running at a speed of 2.7m/s and 3.3m/s on an instrumented treadmill (Bertec, USA). Biomechanical variables included the impulse (IM), impact force (IF), peak vertical ground reaction force (PVGRF), vertical loading rate (VLR), braking impulse (BIM), and propulsion impulse (PIM). Results: The VLR was statistically smaller for the assembling insole (HI, MI & LI) compared with the BI during running at 2.7m/s (p<.05). The PVGRF was greater for the assembling insole (HI, MI & LI) compared with the BI during running at 3.3m/s (p<.05), however, the VLR was statistically smaller for the assembling insole (HI, MI & LI) compared with the BI (p<.05). The comforts (Forefoot, Rearfoot, and overall) were statistically lower for the HI compared with the BI, MI, and LI. The feeling foreignness was statistically higher for the assembling insole (HI, MI & LI) compared with the BI. Conclusion: It was concluded that the assembling insole (HI, MI & LI) may be more effective in the impact absorption compared with the BI during running. However, using assembling insole with systematic changes in hardness may require an adaptation period. Therefore, future study would be necessary to investigate the biomechanical differences and their comfort perception with the changes in the insole hardness over a long period of time. Application: Users" cushion preferences using a guideline for a custom assembly insole will be available in the footwear research and development.

발바닥 부위별 인솔 소재 및 경도 변화가 착화감과 충격 흡수에 미치는 영향

류시현(Sihyun Ryu),길호종(Hojong Gil),공세진(Sejin Kong),최용석(Yongsuk Choi),류지선(Jiseon Ryu),윤석훈(Sukhoon Yoon),박상균(Sang Kyoon Park) 대한인간공학회 2018 大韓人間工學會誌 Vol.37 No.4

Objective: The purpose of this study was to evaluate the biomechanical effects of insole material and hardness in different plantar regions on the comfort and impact absorption during walking and to analyze the correlations between comfort and impact variables. Background: It is necessary to apply materials tailored to the functionalities of different plantar regions during different phases of the gait cycle: the rearfoot portion should absorb the impact force during the heel-contact phase, the midfoot portion should support the entire arch, and the forefoot portion should enhance the swing efficiency during the toe-off phase. Method: Twenty men in their twenties were recruited for the study (age: 23.4±2.7yrs; height: 175.9±4.1㎝; weight: 72.9±9.4㎏). They wore insoles in random order. Pedar-X system (Novel GmbH, USA) and Treadmill (Instrumented treadmill, Bertec, USA) were used to measure the plantar pressure and ground reaction force. The walking speed was set at 1.3㎧ and 1.7㎧. The sampling rate was set at 50㎐ and 1,000㎐, respectively. For comfort testing, the subjects administered a questionnaire survey using the visual analogue scale (VAS) after walking 1km. Three insole models were tested: Insole A using a mixed material with shock-absorbing and anti-rebound components uniformly spread throughout the insole; Insole B and Insole C using sponge and ethylene vinyl acetate (EVA), respectively, as underlying material and strengthened with shock absorber in the rearfoot portion, high-hardness material in the midfoot portion, and anti-rebound function in the forefoot portion. The impulse, mean impact force, initial peak of ground reaction force, and loading rate were calculated. Results: First, Insole B significantly outscored Insole A in terms of the forefoot cushioning comfort (p <.05), with Insole B and C showing higher overall comfort scores compared with Insole A (p <.05). Second, Insole A showed higher mean impact force, initial and peak vertical ground reaction forces, and loading rate compared with Insoles B and C, but without reaching statistical significance. Third, Insole B and C showed statistically higher mean pressure in the midfoot portion compared with Insole A (p <.05). Conclusion: Positive effects in terms of comfort and impact absorption were demonstrated by the insoles fabricated with different materials and hardness tailored to the functionalities of different plantar regions in comparison with the conventional insoles using the uniform material throughout the insole. In particular, positive effects on overall comfort were found to be ascribable to the enhanced hardness in the midfoot portion, which supported the arch more efficiently and contributed to an even distribution of the overall pressure on the plantar. Application: The study results can be applied to insole development as follows: Insole material and hardness should be varied for different plantar regions, and shock absorber and high-hardness material should be used for the rearfoot and midfoot portions, respectively.

인체 관절각의 Variability가 태권도 지르기 속도에 미치는 효과

류시현 ( Sihyun Ryu ) 한국체육대학교 체육과학연구소 2019 스포츠사이언스 Vol.37 No.1

본 연구의 목적은 태권도 지르기 시 인체 관절각의 Lyanpunov exponent (LyE)가 지르고 당기는 속도에 미치는 영향을 살펴보는 것이다. 연구의 대상자는 태권도 품새 선수 18명 (나이: 20.8±2.4 세, 신장: 171.7±7.1 cm, 체중: 66.2±8.3 kg)으로 선정하였다. 태권도 앞굽이 바로지르기를 반복적으로 수행하는 과정에서 인체 관절각에 대한 LyE를 계산하고 LyE와 지르기 최대속도 간의 상관계수를 산출하였다. 그 결과는 다음과 같다. 첫째, 지르는 주먹의 최대 속도는 7.54±1.19 m/s로 나타났으며, 당기는 주먹의 최대속도는 7.76±2.51 m/s로 나타났다. 둘째, 상, 하지 관절각의 LyE는 전반적으로 근위에서 원위 부위로 갈수록 증가하는 경향을 보였다. 셋째, 지르고 당기는 주먹의 최대속도와 당기는 어깨관절각의 LyE 간에는 정적 상관관계(r=.498, r=.406)가 나타났으며, 당기는 주먹의 최대속도와 앞굽이 앞다리 무릎관절각의 LyE 간에는 부적 상관관계(r=-.451)가 나타났다. 위 결과를 바탕으로 빠른 속도의 지르기를 수행하기 위해서는 안정된 서기를 바탕으로 지르기를 수행해야 하며, 빠른 속도의 지르기를 수행한다면, 상지의 일관성은 다소 감소될 수 있다. The purpose of this study was to investigate Lyanpunov exponent (LyE) of joint angle during Taekwondo Jireugi and effects of LyE on velocity of Jireugi. Eighteen Poomsae athletes (age: 20.8±2.4 years, height: 171.7±7.1 cm, Body weight: 66.2±8.3 kg) participated in this study. The maximum speed of pushing fist was 7.54±1.19 m/s and pulling fist was 7.76±2.51 m/s. This study was trended to increase the LyE from proximal joint to distal joint. This study was shown positive relation between the maximum speed of pushing and pulling, and the LyE of pulling shoulder joint (r=.498, r=.406). This study was shown negative relation between the maximum speed of pulling and the LyE of forward knee joint (r=.451). Based on the results of this study, it is considered that the stability of stance are directly related to the speed of Jireugi in Taekwondo.

김대중의 역사인식과 한국사 이해의 특징

류시현 ( Ryu Sihyun ) 호남사학회(구 전남사학회) 2020 역사학연구 Vol.80 No.-

김대중은 한국 현대사를 대표하는 정치가이자 국정 책임자인 대통령을 지냈던 인물이다. 그의 활동과 영향력과 관련해서 외교와 통일을 포함한 정치 영역에서의 연구 성과는 많이 축적되어 있다. 하지만 상대적으로 정치적 활동과 결정의 기반이 되었던 그의 사상에 관한 연구는 적었다. 따라서 김대중의 정치활동에 기반이 되었던 그의 역사 인식이 어떠했는가에 관한 연구가 요구된다. 김대중은 아놀드 토인비와 그의 『역사의 연구』에서 많은 영향을 받았다. 인류문명사의 ‘도전과 응전’, ‘창조적 소수자’의 역할 등의 개념을 한국 역사 이해에 적용하고자 했으며, 민족사의 적용과정에서 형성된 역사 진행과정에 관해 ‘낙관’적 전망을 가지게 되었다. 또한 민중 주체의 개혁을 긍정적으로 이해했다. 세계사와 한민족사의 경험에 기초한 역사 발전에 관한 믿음은 민족주의에 관한 유연한 인식이 가능하게 만들었다. 그리고 민족사에 관한 이해는 민주주의와 통일이란 과제를 해결하기 위한 방안으로 활용했다. 역사를 좋아하고, 역사의 심판을 중요시 했던 김대중은 자신의 역사관을 그의 정치활동의 정신적, 사상적 자산으로 삼았다. Kim Dae-jung a politician who represents the modern Korean history and national responsibility, a former president. Reflecting his influence, many research achievements in the political area including diplomacy and unification have been accumulated. However there was less researches on his ideas which were relatively the basis of political activities and decisions. Therefore his A Study on the historical perception as well as Kim Dae-jung's political activities is required. Arnold Toynbee and his book A Study of History affected to Kim Dae-jung. He wanted to apply the role of "challenge and retort" and "creative minority" in the history of human civilization to understanding Korean history. The "optimistic" outlook on the progress of history, which was formed during the application of national history was given. And positively understood the reform of the people's subjects. Belief in the development of history based on the experience of world history and Korean history has made it possible to have a flexible perception of nationalism. And the understanding of national history was used as a way to solve the challenges of democracy and unification. Kim Dae-jung regards history as his mental, spiritual assets of his political activities.

신발의 뒤꿈치 형태가 보행 시 충격과 생체역학적 특성에 미치는 영향

류시현(Sihyun Ryu),박상균(Sang-Kyoon Park) 대한인간공학회 2020 大韓人間工學會誌 Vol.39 No.3

Objective: The purpose of this study was to investigate the effects of a curved shoe design of the heel of a shoe on the impact variables, ankle joint angle, and COP (center of pressure) during walking. Background: Shoe design is one of important characteristics in the development of walking shoes as it has to be considered for the mechanism of human movement. Method: Twenty healthy male adults (age: 23.6±2.9 years, body mass: 71.0±8.7kg, height: 175.8±5.0cm) participated in the study. The data was collected using eight infrared cameras during walking at a speed of 1.3m/s and 1.7m/s on an instrumented treadmill. Results: The impulse and peak VGRF (vertical ground reaction force) were statistically smaller for the RHS and RLHS compared with the NS during walking of 1.3m/s & 1.7m/s (p <.05). The ankle plantarflexion angle at toe off, the ROM (range of motion) of dorsi-plantarflexion, and ROM of inversion-eversion were statistically smaller for the RHS and RLHS compared with the NS during walking of 1.7m/s (p <.05). The antero-posterior COP range and jerk were statistically smaller for the RHS and RLHS compared with the NS during walking of 1.7m/s (p <.05). Conclusion: It is concluded that RLHS is slightly effective in reducing shocks, RLHS and RHS help walk smoothly and naturally compared to NS, and RLHS improves the stability of the ankle joints compared to NS, and RLHS during walking. Application: The findings would be helpful when developing the walking shoes with biomechanical functions.

장시간 보행이 중년여성의 발의 형태와 움직임 및 지면반력에 미치는 영향

박상균(Sang-Kyoon Park),류시현(Sihyun Ryu),황원섭(Won-Seob Hwang),이정호(Jungho Lee) 대한인간공학회 2018 大韓人間工學會誌 Vol.37 No.5

Objective: The purpose of this study was to investigate the changes in foot morphology and foot motion using a multi-segment foot model, and ground reaction forces during prolonged walking in healthy middle-aged females. Background: As people have experienced improved cardiovascular and muscularskeletal health, the popularity of prolonged walking has increased. However, only a few studies have suggested that prolonged walking may increase the risk of lower extremity joint injuries due to abnormal loading and decreased stability after muscle fatigue. Method: Forty-two healthy middle-aged females (mean age: 45.4 ± 2.3 years, mean height: 160.7 ± 4.8cm, mean weight: 59.2 ± 6.9kg, mean foot size: 23.3 ± 0.7cm) participated in the study. The participants went through measurements of foot morphology and Q- angle before and after 40 minutes" walking. The participants were asked to walk at a speed of 1.1m/sec for 40 minutes. Foot motion and ground reaction forces were collected at three time intervals (0, 20 and 40 minutes). Changes in variables were compared at an alpha level of .05 using a paired t-test and repeated ANOVA, respectively. Results: Arch index was decreased and Q angle was increased after 40 minutes" walking (p < 0.05). Increased toe out angle and attack angle of the foot at initial contact were observed as walking time progressed (p < 0.05). Increased flexion angles of multi-segment foot were found with increased walking time (p < 0.05). Finally, the participants experience greater braking force after 40 minutes" walking compared with 0 minutes and after 20 minutes (p < 0.05). Conclusion: The participants experience kinematic and kinetic changes of the foot during a prolonged period of walking. Application: The current findings suggest important biomechanical considerations when applying a walking intervention in a clinical trial to improve fitness or in developing adequate walking shoes.

체질량지수(BMI) 차이에 따른 보행요인과 하지관절 각도, 국면협응지수(PCI) 비교분석

김종빈 ( Jongbin Kim ),류시현 ( Sihyun Ryu ),박상균 ( Sang-kyoon Park ) 한국체육대학교 체육과학연구소 2020 스포츠사이언스 Vol.38 No.1

본 연구의 목적은 체질량지수 (BMI; Body Mass Index)에 따른 보행요인과 하지관절 각도, 양발 협응력을 비교분석 하였다. 이를 위해 20대 성인남성을 BMI지수 기준으로 비만체중집단 15명(25 ≤ BMI < 30)과 정상체중집단 15명(18.5 ≤ BMI < 23)으로 선정하였고 8대의 적외선 카메라로 30 스트라이드를 촬영하였다. BMI지수의 차이에 따라 보행요인과 2차원 하지관절각도와 가동범위를 산출하였고, 국면협응지수(PCI)를 분석 하였다. 두 그룹을 간에 차이를 검증하기 위해 독립 t-test를 실시하였고, 유의수준은 α = .05로 설정하였다. 그 결과, 오른발 보장길이, 왼발 활보장길이, 단하지 지지율은 정상집단이 크게 나타났고(p<.05), 왼발 양하지 지지율은 비만집단이 크게 나타났다(p<.05). 하지관절의 각도는 지면에서 떨어지는 순간 엉덩관절에서 비만집단이 크게 나타났고(p<.05), 무릎관절에서는 정상집단이 크게 나타났다(p<.05). 지지구간의 하지관절 가동범위는 엉덩관절에서는 정상집단이 크게 나타났으며 무릎관절각도에서 비만집단이 크게 나타났으며(p<.05), 스윙구간의 엉덩관절 가동범위도 정상집단이 크게 나타났다(p<.05). 발목관절에서는 가동범위의 차이가 나타나지 않았다. PCI지수는 통계적 차이는 나타나지 않았지만 정상집단의 양발 협응력이 높게 나타났다. 따라서 정상집단은 비만체중집단과 비교해 보장과 활보장 길이를 증가시키고 하지관절의 가동범위를 크게 하여 하지관절 움직임에 직접적인 영향을 미치는 것으로 판단된다. The purpose of this study was to comparatively analyze walking factors, angles of lower extremity joints, and bilateral coordinated pressure as a difference in body mass index (BMI). Based on the BMI index, adult men in their 20s were selected as 15 obese body recombinations (25≤BMI <30) and 15 normal body recombinations (18.5≤BMI <23). 8 infrared cameras were used to collect 30 steps of walking. According to the difference of BMI indicators, the walking factor, 2D lower limb joint angle and range of motion were calculated, and the phase coordination index (PCI) was analyzed. An independent t test was performed to verify the difference between the two groups, and the significance level was set to α = .05. In the result, step length of the right foot and stride length of the left foot are longer in normal group(p <.05) while the obese group has a greater left foot support rate (p <.05). The obesity group show greater angle of the hip joint while normal group shows greater angle of the knee at take off of the foot (p <.05). The range of motion of hip joint is greater during the support phase in the normal group while the range of motion of knee joint in the obese group is greater during the support phase (p <.05). The range of motion of hip joint during the swing phase is also greater in the normal group (p <.05). There is no difference in motion of the ankle between two groups. Although the PCI was not statistically different, the normal group had relatively greater bilateral coordination than obese group. Therefore, it can be considered that normal people directly affect the movement of the lower limb joints by increasing step and stride length with increasing the range of motion of the lower limb joints compared with obese people.