Development of a synchronized AR Framework for Multi-user

Sangheon Park,Hyunwoo Cho,Young-Suk Yoon,Sung-Uk Jung 한국콘텐츠학회 2018 한국콘텐츠학회 ICCC 논문집 Vol.2018 No.12

모래주머니를 이용한 팔목과 몸통의 무게 증가가 만성 뇌졸중 환자들의 보행에 미치는 영향

( Sangheon Park ),( Hee Sung Lim ),( Sukhoon Yoon ) 한국운동역학회 2021 한국운동역학회지 Vol.31 No.1

Objective: This study aimed to determine the effect of wrist and trunk weight loading using sandbags in stroke patients in order to provide the quantitative data for enhancement of gait movement. Method: Twelve stroke patients, who have been diagnosed with hemiplegia over a year ago, were participated in this study. All subjects were asked to perform normal walking [N], wrist sandbag walking [W], wrist & trunk sandbag walking [WT], and both wrist sandbag walking [B] and both wrist & trunk sandbag walking [BT], respectively. Eight infrared cameras were used to collect the raw data. Gait parameters, arm swing, shoulder-pelvic kinematics, and lower extremity joint angle were calculated to examine the differences during walking. Results: As a result, there were no significant differences in the gait parameters, shoulder-pelvis, and lower extremities joint angles, but significant differences were found in the range of motion and the anteversion in arm swing. Conclusion: Wrist and trunk weight loading using sandbags affected the movement of the upper extremities only while it did not affect the movement of the lower extremities. It implies that it can reduce the risk of falling caused by a sudden movement change in lower extremities. In addition, the wrist and trunk weight loading using sandbags can induce changes in movement of the upper extremities independently and contribute to functional rehabilitation through resistance training.

Temperature-dependent optical properties of hybrid organic–inorganic perovskite single crystals (CH₃NH₃PbI₃ and CH₃NH₃PbBr₃)

Park, Sangheon,Seo, Yu-Seong,Ahn, Chang Won,Woo, Won Seok,Kyhm, Jihoon,Lee, Sang A,Kim, Ill Won,Hwang, Jungseek IOP 2019 Journal of Physics. D, Applied Physics Vol.52 No.33

<P>We investigated the temperature-dependent optical properties of methylammonium lead iodide (MAPbI<SUB>3</SUB>: CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB>) and bromide (MAPbBr<SUB>3</SUB>: CH<SUB>3</SUB>NH<SUB>3</SUB>PbBr<SUB>3</SUB>) single crystals using optical spectroscopy and photoluminescence (PL) techniques. We obtained the optical conductivity from the measured reflectance spectra of the single crystals at various temperatures using a Kramers–Kronig relation and measured their PL spectra at selected temperatures. We observed structural phase transitions and a mixed-structure phase from the infrared-active phonon modes in the measured optical data. In the mixed phase, we observed unsystematic temperature-dependent bandgap behavior in both optical and PL spectra. The unsystematic bandgap behavior can be understood by taking into account both the contributions of thermal effect and structural phase to the size of the bandgap in the temperature region of the mixed structural phase or the structural phase transition. Interestingly, we also observed quantitative differences in those optical and PL properties between thin film and single crystal samples. We expect that our results will supply helpful information for further development of hybrid organic–inorganic perovskite solar cells.</P>

농구 패스 리시브 시 숙련자와 비숙련자 간의 동작의 부드러움과 손가락 및 상지 협응의 차이

( Sangheon Park ),( Hee Sung Lim ),( Sukhoon Yoon ) 한국운동역학회 2019 한국운동역학회지 Vol.29 No.2

Objective: The purpose of this study was to investigate the differences of smoothness and coordination of the fingers and upper extremities between skilled and non-skilled players during receiving the basketball. Method: Ten male recreational basketball players (age: 23.2±2.7 yrs., career: 8.6±1.6 yrs., height: 177.3±6.0, weight: 72.9±8.5 kg) careering over five years and ten non-skilled males (age: 27.3± 1.5 yrs., height: 173.7±5.6, weight: 73.2±12.6 kg) were participated in this study. Then, participants were asked to perform basketball receiving movement for ten times. The receiving movements were recorded by eight infrared cameras (Oqus 300, Qualisys, Sweden). The collected rad data were calculated to duration of basketball receiving, Jerk-Cost, CRP and CRP variability. Results: The CRP of MCP-Wr, Wr-El in skilled group were greater than non-skilled group (p<.05). The CRP variability of El-Sh in non-skilled group was greater than skilled group (p<.05). Conclusion: These results suggest that skilled players perform more effective movement for impact absorption from the basketball. Moreover, the skilled players have consistent movement patterns during basketball performance. Lastly, it is important to train finger sensation and cognitive ability of thrown basketball from the passer.

농구 패스 리시브 시 숙련자와 비숙련자 간의 동작의 부드러움과 손가락 및 상지 협응의 차이

Park, Sangheon,Lim, Hee Sung,Yoon, Sukhoon 한국운동역학회 2019 한국운동역학회지 Vol.29 No.2

Objective: The purpose of this study was to investigate the differences of smoothness and coordination of the fingers and upper extremities between skilled and non-skilled players during receiving the basketball. Method: Ten male recreational basketball players (age: $23.2{\pm}2.7yrs.$, career: $8.6{\pm}1.6yrs.$, height: $177.3{\pm}6.0$, weight: $72.9{\pm}8.5kg$) careering over five years and ten non-skilled males (age: $27.3{\pm}1.5yrs.$, height: $173.7{\pm}5.6$, weight: $73.2{\pm}12.6kg$) were participated in this study. Then, participants were asked to perform basketball receiving movement for ten times. The receiving movements were recorded by eight infrared cameras (Oqus 300, Qualisys, Sweden). The collected rad data were calculated to duration of basketball receiving, Jerk-Cost, CRP and CRP variability. Results: The CRP of MCP-Wr, Wr-El in skilled group were greater than non-skilled group (p<.05). The CRP variability of El-Sh in non-skilled group was greater than skilled group (p<.05). Conclusion: These results suggest that skilled players perform more effective movement for impact absorption from the basketball. Moreover, the skilled players have consistent movement patterns during basketball performance. Lastly, it is important to train finger sensation and cognitive ability of thrown basketball from the passer.

Gender Dfferences in Ground Reaction Force Components

Park, Sang-Kyoon,Koo, Seungbum,Yoon, Suk-Hoon,Park, Sangheon,Kim, Yongcheol,Ryu, Ji-Seon Korean Society of Sport Biomechanics 2018 한국운동역학회지 Vol.28 No.2

Objective: The aim of this study was to investigate gender differences in ground reaction force (GRF) components among different speeds of running. Method: Twenty men ($age=22.4{\pm}1.6years$, $mass=73.4{\pm}8.4kg$, $height=176.2{\pm}5.6cm$) and twenty women ($age=20.7{\pm}1.2years$, $mass=55.0{\pm}8.2kg$, $height=163.9{\pm}5.3cm$) participated in this study. All participants were asked to run on an instrumented dual belt treadmill (Bertec, USA) at 8, 12, and 16 km/h for 3 min, after warming up. GRF data were collected from 30 strides while they were running. Hypotheses were tested using one-way ANOVA, and level of significance was set at p-value <.05. Results: The time to passive peaks was significantly earlier in women than in men at three different running speeds (p<.05). Further, the impact loading rates were significantly greater in women than in men at three different running speeds (p<.05). Moreover, the propulsive peak at 8 km/h, which is the slowest running speed, was significantly greater in women than in men (p<.05), and the vertical impulse at 16 km/h, which is the fastest running speed, was significantly greater in men than in women (p<.05). The absolute anteroposterior impulse at 8 km/h was significantly greater in women than in men (p<.05). In addition, as the running speed increased, impact peak, active peak, impact loading rate, breaking peak, propulsive peak, and anteroposterior impulse were significantly increased, but vertical impulse was significantly decreased (p<.05). Conclusion: The impact loading rate is greater in women than in men regardless of different running speeds. Therefore, female runners might be exposed to the risk of potential injuries related to the bone and ligament. Moreover, increased running speeds could lead to higher possibility of running injuries.

The Effect of Types of Initial Drive-in Steps on Technical Factors in Basketball

Park, Sangheon,Yoon, Sukhoon Korean Society of Sport Biomechanics 2018 한국운동역학회지 Vol.28 No.3

Objective: The purpose of this study was to investigate the effect of types of drive-in initial steps in basketball on technical factors, to provide basic information for the enhancement of basketball skill. Method: Ten men (age: $24.70{\pm}2.26years$; height: $181.00{\pm}5.72cm$; weight: $75.70{\pm}8.23kg$; career length: $10.00{\pm}3.59years$), each with a career length of over five years and no history of injury to the lower extremities within the prior six months, participated in this study. They were asked to perform four types of drive-in movements at $35{\sim}60^{\circ}$, wearing their own shoes, after running from a start line 5 m away and catching a basketball passed by an expert passer. The drive-in movements were measured by eight infrared cameras (Oqus 300, Qualisys, Sweden). Collected raw data were used to calculate total initial step time, displacement, velocity, center of mass (COM) height, and COM velocity. Results: Total initial step displacement and velocity of cross drive-ins (JC, SC) were greater than that of direct drive-ins (JD, SD; p < .05). COM velocity of cross drive-ins (JC, SC) was also greater than that of direct drive-ins (JD, SD; p < .05). Conclusion: Our results indicated that cross drive-ins, regardless of stop step type, are more effective than direct drive-ins. This is because cross drive-ins are technically bold due to less influence from walking violations and double dribble rules in basketball. However, using one-sided movement is too difficult to play in competitive game; therefore, basketball players should develop the ability to choose appropriate movement frequency.

Optimum Morphology of Mixed-Olivine Mesocrystals for a Li-Ion Battery

Park, Kimin,Kim, Jaewon,Wi, Sungun,Lee, Sangheon,Hwang, Taehyun,Kim, Jaewook,Kang, Joonhyeon,Choi, Joon-Phil,Nam, Seunghoon,Park, Byungwoo American Chemical Society 2018 Inorganic Chemistry Vol.57 No.10

<P>In this present work, we report on the synthesis of micron-sized LiMn<SUB>0.8</SUB>Fe<SUB>0.2</SUB>PO<SUB>4</SUB> (LMFP) mesocrystals via a solvothermal method with varying pH and precursor ratios. The morphologies of resultant LMFP secondary particles are classified into two major classes, flakes and ellipsoids, both of which are featured by the mesocrystalline aggregates where the primary particles constituting LMFP secondary particles are crystallographically aligned. Assessment of the battery performance reveals that the flake-shaped LMFP mesocrystals exhibit a specific capacity and rate capability superior to those of other mesocrystals. The origin of the enhanced electrochemical performance is investigated in terms of primary particle size, pore structure, antisite-defect concentration, and secondary particle shape. It is shown that the shape of the secondary particle has just as much of a significant effect on the battery performance as the crystallite size and antisite defects do. We believe that this work provides a rule of design for electrochemically favorable meso/nanostructures, which is of great potential for improving battery performance by tuning the morphology of particles on multilength scales.</P><P>Micron-sized LiMn<SUB>0.8</SUB>Fe<SUB>0.2</SUB>PO<SUB>4</SUB> mesocrystals having various morphologies were facilely synthesized via a solvothermal method. The origin of the different electrochemical performances of the mesocrystals was investigated in terms of primary particle size, pore structure, antisite-defect concentration, and secondary particle shape. We believe that this work can provide a rule of design for the electrochemically favorable meso/nanostructures, which is of great potential for improving battery performance.</P> [FIG OMISSION]</BR>

The Effect of Types of Initial Drive-in Steps on Technical Factors in Basketball

( Sangheon Park ),( Sukhoon Yoon ) 한국운동역학회 2018 한국운동역학회지 Vol.28 No.3

Objective: The purpose of this study was to investigate the effect of types of drive-in initial steps in basketball on technical factors, to provide basic information for the enhancement of basketball skill. Method: Ten men (age: 24.70±2.26 years; height: 181.00±5.72 cm; weight: 75.70±8.23 kg; career length: 10.00±3.59 years), each with a career length of over five years and no history of injury to the lower extremities within the prior six months, participated in this study. They were asked to perform four types of drive-in movements at 35~60°, wearing their own shoes, after running from a start line 5 m away and catching a basketball passed by an expert passer. The drive-in movements were measured by eight infrared cameras (Oqus 300, Qualisys, Sweden). Collected raw data were used to calculate total initial step time, displacement, velocity, center of mass (COM) height, and COM velocity. Results: Total initial step displacement and velocity of cross drive-ins (JC, SC) were greater than that of direct drive-ins (JD, SD; p < .05). COM velocity of cross drive-ins (JC, SC) was also greater than that of direct drive-ins (JD, SD; p < .05). Conclusion: Our results indicated that cross drive-ins, regardless of stop step type, are more effective than direct drive-ins. This is because cross drive-ins are technically bold due to less influence from walking violations and double dribble rules in basketball. However, using one-sided movement is too difficult to play in competitive game; therefore, basketball players should develop the ability to choose appropriate movement frequency.

수술 중 환자 관리

Sangheon Park 대한외과학회 2012 대한외과학회 학술대회 초록집 Vol.2012 No.11