Changes in Spatiotemporal Parameters and Lower Limb Coordination During Prosthetic Gait Training in Unilateral Transfemoral Amputees

Yunhee Chang,Chang-Yong Ko,Bo Ra Jeong,Jung Sun Kang,Hyuk-Jae Choi,Gyoosuk Kim,Hyunjun Shin,Sehoon Park 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.3

When applying prosthetic gait training to patients with lower limb amputation, monitoring the gait change process is crucial for establishing and modifying rehabilitation training plans. In addition, since human gait involves complex movement of several joints, it is necessary to analyze the organic movement of adjacent joints rather than a single joint in the lower extremities for understanding the process of gait change. Therefore, this study aimed to analyze changes in spatiotemporal parameters and lower limb coordination during prosthetic gait training in unilateral transfemoral amputees (TFAs). This retrospective case–control study included 10 unilateral TFAs and 10 healthy individuals as controls. TFAs received prosthetic gait training for 12 weeks and gait changes were analyzed every 2 weeks using a 3D motion analysis system. The measured variables were spatiotemporal parameters and the continuous relative phase between hip and knee joints. The highest improvement in walking speed was seen at week 4 of training, and the continuous relative phase was most symmetric at week 8. The lower limb coordination pattern was more in-phase in the TFAs than in the controls, and the coordination variability was also lower for the TFAs than for the controls. In addition, the rate of change in lower limb coordination of TFAs was lower than that of spatiotemporal parameters and was significantly different from that of the controls even after training. Considering that the decrease in lower limb coordination is related to gait efficiency, balance, and risk of fall, there is a need to develop therapeutic strategies that can further improve the coordination of TFAs.

Knowledge Management through HRM

Yunhee Chang(장윤희),Kyungmi Chun(전경미) 대한경영학회 2014 대한경영학회 학술발표대회 발표논문집 Vol.2014 No.2

Does Maternal Employment Affect Parental Time Allocated to Children's Food Consumption and Physical Activity? Evidence from the Korean Time Use Survey

Chang, Yunhee,Lee, Seungmie The Korean Home Economics Association 2012 International Journal of Human Ecology Vol.13 No.2

This study uses the 1999-2009 Korean Time Use Survey to explore how mothers' employment affects parental time spent in activities that may relate to their children's weight. Specifically, it estimates two-part regression models to assess the effects of maternal employment upon the amount of time mothers spend in activities potentially related to their preschool children's eating and physical activity. The findings suggest that working mothers and those mothers who work longer hours allocate significantly less time in food preparation, eating with the child, and supervising the child's physical activity than mothers who are not employed and those who work fewer hours. The paper also finds that spouses of working mothers do not allocate more time to these activities to offset the reduction in mothers' time. Also, using local unemployment rates as instrumental variables, maternal employment is found to allow mothers to spend significantly more time on food preparation and family meals, although its effect on mothers' total childcare time is negative. Several aspects of Korean society may have made the relationship between maternal employment and childhood weight issues different from what was found in other countries.

Inhibitory Effects of Super Sweet Corn Silk Extract on Adipocyte Differentiation in 3T3-L1 Adipocyte

Chang Jun Lee,Yunhee Baek,Han Sung Kang,Sang Yoon Choi 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

This study was performed to evaluated the inhibitory effects of super sweet corn silk extracts (SCS) on the differentiation and lipogenesis in 3T3-L1 adipocytes. Generally, corn silk is known to be anti-obesity material, but the effect of SCS has not been reported yet. 3T3-L1 adipocyte differentiation were induced by treatment with MDI including IBMX, dexamethasone and insulin. And then, the morphologic changes and the degrees of lipid accumulation of 3T3-L1 cells were measured by Oil Red O staining assay. The protein expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), sterol regulatory element-binding protein 1 (SREBP-1), and FAS was measured by western blot assay. As the results, SCS potently attenuated adipogenesis and adipogenic transcriptional factors compared to the only MDI treated group. Theses results suggest that SCS may be a good candidate as an ingredient in anti-obesity products.

Analysis of Body Slip and Seat Pressure in Powered Wheelchairs with Two-Slide Recline System

Yunhee Chang,Yong Cheol Kim,Ki Tae Nam,Jung Sun Kang,Bo Ra Jeong,Eung-Pyo Hong 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.3

Recline and tilt functions are the most desirable features for relieving seating pressure to decrease the risk of pressure ulcers. This study presents a new recline mechanism for a powered wheelchair for users sitting for a long duration. We analyzed the effect of a developed two-slide mechanism. In this study, body slip distance and buttock pressure were measured during wheelchair reclining and repositioning using a three-dimensional motion analysis and a pressure measurement system in 10 healthy subjects. Non-slide, one-slide, and two-slide versions were compared. During reclining, the total slip distance along the backrest with two slides was 40.6 mm, which was 77% and 44% smaller than non-slide and one-slide backrests, respectively. The slip variation of the non-slide was 38 mm at the beginning of recline in the initial seated position, and the slip distance tended to decrease as the recline angle increased. However, in the two-slide backrest, the average slip distance per 10° interval was only 5.1 ± 1.1 mm. In addition, we observed a similar slip in repositioning as in reclining, and the slip distance along the seat also decreased most in the two-slide backrest. The buttock pressure gradually decreased from 100° to 150° and then increased again from 160°, but the two-slide backrest showed a tendency to decrease at larger angles of recline and decreased by 59% of the maximum pressure. This study confirms that the two-slide system reduces body slip and buttock pressure, and it is expected that risk factors caused by the long-term use of a wheelchair can be minimized.

Antecedents of Within-industry Diversification: Evidence from the Korean Life Insurance Industry

Yunhee Chang(장윤희),Kuhyuk Kwon(권구혁 ),Kyungmi Chun(전경미),Houk Lee(이호욱) 연세대학교 경영연구소 2021 연세경영연구 Vol.58 No.2

본 연구는 기존 전략경영 문헌에서 다각화와 기업 성과의 상관관계에 대한 연구에 비해 상대적으로 많이 연구되지 않았던 산업 내 다각화의 동인을 탐구하는 실증 연구라는 점에 의의가 있다. 그동안 회계/재무 분야에서 연구된 보험 산업의 재무적 특성을 주로 고려한 연구에서 나아가, 본 연구는 다각화에 동원될 수 있는 다양한 자원의 측면과 기업의 지배구조의 성격에 따라 산업 내 다각화의 특성에 어떠한 영향이 있는지를 종합적으로 고려한 연구라는 점에서 학술적인 의의를 갖는다. 또한, 본 연구의 차별적 공헌점은 바로 한국의 생명보험산업이라는 단일 산업을 대상으로 다양한 자원과 기업의 지배 구조의 성격을 검증할 수 있는 패널 데이터를 구축하고 이를 기반으로 실증 연구를 진행하였다는 점이다. 해당 산업 내 다양한 제품 출시는 보험 산업이라는 제도적 특성이 존재함에도, 개별 기업의 보험 산업의 자원과 역량을 최대한 활용할 수 있는 가장 가까운 산업인 손해보험 산업으로의 진출이 제도적으로 불가능하다. 이러한 상황에서 기업 내부 자원의 다양한 성격과 기업의 지배 구조가 다각화 추구에 어떠한 영향을 미치는지를 검증하였다. 먼저, 기존 다각화 연구에서 일원화되었던 기업의 재무 자원이 본 실증 연구의 대상 산업에서는 기존 제품에 구분하여 별도의 회계 계정을 유지하고 있어 다각화를 위한 전용 재무 자원을 측정하고 검증하였다는 연구의 공헌점이 있다. 또한, 기업이 내부에 보유한 자원이라 할지라도 기존 주력 상품의 판매에 최적화되어 있는 자원(비대면 판매 채널)이 새로운 제품 출시에 있어서는 부의 영향을 미친다는 사실을 실증적으로 검증하였다는 점은 기존 성과 중심의 산업 내 다각화 연구에 비해 본 연구가 갖는 차별적 공헌점이라 할 수 있다. 향후 본 연구를 확장하여 후속 연구에서는 산업 내에서 제품 다각화를 추구하는 기업의 전략적 행위를 탐색함에 있어 더 다양한 기업 지배 구조 성격 변수와 자원의 성격을 추가적으로 고려할 수 있을 것이다. 또한, 단일 산업 내에서의 제품 다각화가 궁극적으로 어떠한 성과 함의를 지니는지에 대해서도 고려할 수 있을 것이다. We examine what makes firms diversify within an industry, considering several characteristics of corporate resources and the moderating influence of corporate governance. While most diversification studies have investigated how diversification influences firm performance without consideration of the industry to which the firm belongs, this study verifies what drives within-industry diversification with consideration of internal resources and corporate governance. Similarly, research in the fields of corporate finance and insurance has focused mostly on the impact of financial characteristics on firm performance; in this study, we examine many aspects of corporate internal resources that can be mobilized for the purpose of diversification, sales resources that are optimized to benefit the existing product category. To verify our results empirically, we investigate firms in the Korean life insurance industry where within-industry diversification is clearly evident. In this industry, firms intentionally and institutionally pursue within-industry diversification similar to how they pursue product-level diversification; thus, within-industry diversification closely mirrors detailed strategic choices at the product level. We collected data from 25 insurers for the fiscal years ranging from 2007 to 2017 to form 264 panel data for analysis. The results of the empirical analysis suggest that firms with internal resources such as affiliate relationships for new product management show tendencies toward high within-industry diversification. However, firms with accumulated resources idealized for the existing product market exhibit less within-industry diversification. This study’s theoretical contribution is to provide a comprehensive perspective on within-industry diversification. This construct has not been explored, nor have its characteristics and determinants been clearly identified as compared to inter-industry diversification.

Evaluation of the QuantaMatrix Multiplexed Assay Platform for Molecular Diagnosis of Multidrug- and Extensively Drug-Resistant Tuberculosis Using Clinical Strains Isolated in Myanmar

Yunhee Chang,Seoyong Kim,Yeun Kim,Phyu Win Ei,Dasom Hwang,Jongseok Lee,장철훈,HyeyoungLee 대한진단검사의학회 2020 Annals of Laboratory Medicine Vol.40 No.2

Background: Although the incidence of tuberculosis (TB) is decreasing, cases of multidrug-resistant (MDR) TB and extensively drug-resistant (XDR) TB continue to increase. As conventional phenotype drug susceptibility testing (pDST) takes six to eight weeks, molecular assays are widely used to determine drug resistance. we developed QuantaMatrix Multiplexed Assay Platform (QMAP) MDR/XDR assay (QuantaMatrix Inc., Seoul, Korea) that can simultaneously detect mutations related to both first- and second-line drug resistance (rifampin, isoniazid, ethambutol, fluoroquinolones, second-line injectable drugs, and streptomycin). Methods: We used 190 clinical Mycobacterium tuberculosis (MTB) strains isolated from Myanmar, compared QMAP and pDST results, and determined concordance rates. Additionally, we performed sequence analyses for discordant results. Results: QMAP results were 87.9% (167/190) concordant with pDST results. In the 23 isolates with discordant results, the QMAP and DNA sequencing results completely matched. Conclusions: The QMAP MDR/XDR assay can detect all known DNA mutations associated with drug resistance for both MDR- and XDR-MTB strains. It can be used for molecular diagnosis of MDR- and XDR-TB to rapidly initiate appropriate anti-TB drug therapy.

Biological characterization of bacterial shot hole disease on stone fruits in Korea

Chang-Gi Back,Yun Du Do,Mi-Jeong Park,Yunhee Seo,Chang Yeol Yang,Sung-Jong, Kim,Jong-Han Park 한국농약과학회 2018 한국농약과학회 학술발표대회 논문집 Vol.2018 No.10

전동기 회전체 광학기반 온도 측정법 탐색 연구

장윤희(Yunhee Chang),유지형(Jihyung Yoo) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6

Comparison of Ankle Angle Adaptations of Prosthetic Feet with and without Adaptive Ankle Angle during Level Ground, Ramp, and Stair Ambulations of a Transtibial Amputee: A Pilot Study

Ko, Chang-Yong,Kim, Sol-Bi,Kim, Jong Kwon,Chang, Yunhee,Kim, Shinki,Ryu, Jeicheong,Mun, Museong Korean Society for Precision Engineering 2014 International Journal of Precision Engineering and Vol.15 No.12

This study aimed to investigate kinetics and kinematics of the ankle joint during level ground, ramp, and stair ambulations using different types of adaptive ankle feet (AAFs), Proprio-Foot<TEX>$^{TM}$</TEX> (<TEX>$\ddot{O}$</TEX>ssur, IcEland), <TEX>$\acute{e}$</TEX>lan foot (Endolite, USA), and Echelon foot (Endolite, USA). A transtibial amputee was asked to walk on a level ground, a ramp with a <TEX>$7^{\circ}$</TEX> slope, and a stair of height 15 cm. The ankle angle and symmetry index (SI) based on the symmetry of the external work performed were measured for AAFs and ambulation. The single support time and stance phase during ambulation were higher for AAFs than the fixed ankle foot. During level ambulation, dorsiflexion increased for all AAFs. During slope ascent ambulation, dorsiflexion increased for the <TEX>$\acute{e}$</TEX>lan foot and Proprio-Foot<TEX>$^{TM}$</TEX>, as well as during the swing phase of the Echelon foot. During slope descent ambulation, the maximum dorsiflexion decreased for the Proprio-Foot<TEX>$^{TM}$</TEX>. During stair ascent, the <TEX>$\acute{e}$</TEX>lanElan foot and Proprio-Foot<TEX>$^{TM}$</TEX> feet improved the dorsiflexion. During stair descent, all AAFs improved the dorsiflextion. Furthermore, SI increased for most of the adaptive ankle feet for all terrain conditions. These results indicate that AAFs can be used to improve the kinetics and kinematics of the ankle on the involved side.