• 한국추진공학회지
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• 제22권6호
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• pp.64-71
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• 2018

가스터빈엔진의 탈설계점 운전 성능해석을 수행하기 위해서는 구성품의 성능 특성을 파악하는 것이 필수적이다. 본 연구에서는 가스터빈의 성능특성을 이해하기 위하여 마이크로 가스터빈엔진 성능시험 장치를 구축하였다. 구축된 마이크로 가스터빈 시험 장치를 이용하여 엔진의 회전수에 따른 유동장내의 온도와 압력 데이터를 수집하였으며, 수집된 실험 데이터를 이용하여 압축기 성능선도를 구성하였다. 터빈 출구부에서 배기가스를 포집하여 연소효율을 계산하였다. 구성된 압축기 성능선도와 연소효율을 GasTurb 성능해석 소프트웨어에 적용하여 지상 정지시의 탈설계점 성능해석을 수행하였고, 측정된 엔진성능데이터와 비교분석을 수행하였다.

• 한국지반신소재학회논문집
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• 제20권4호
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• pp.105-112
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• 2021

항만구조물의 경우 정적인 하중 뿐만 아니라 파압과 같이 반복적인 하중을 받는 구조물임에 따라 반복적인 하중을 받는 구조물의 특성을 파악하는 것이 중요하다. 따라서 본 연구는 반복 수평하중에 의한 말뚝으로 보강된 블록식 방파제의 거동특성을 실내모형실험을 통해 구하였다. 말뚝의 근입 깊이가 깊어질수록 수평저항력이 증가하는 경향이 나타났으며, 하중이 반복될수록 수평저항력의 기울기는 점차 완만하게 나타났다. 휨모멘트는 후열말뚝이 전열말뚝보다 크게 나타났다. 지반내에서의 말뚝의 휨모멘트는 Broms(1964)의 사질토지반에서 말뚝두부 자유일 때와 유사하게 나타났다.

• The Journal of Korean Physical Therapy
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• 제34권5호
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• pp.212-217
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• 2022

Purpose: This study sought to investigate the effects of visual cue deprivation balance training by applying head control feedback to the balance function and the fall index in older people. Methods: The study was conducted on 26 older people at the S Hospital in Gyeongsansi. The patients were randomly divided into the experimental groupI (EGI, n=9), the experimental groupII (EGII, n=9), and the control group (CG, n=8). The three groups were trained for 30 minutes three times a week for four weeks. To assess the patients' static balance function, their limits of stability (LOS) was measured using the BioRescue system, (RM Ingenierie, France), composed of a pressure platform that can measure force in diverse ways, a computer, and a monitor. The dynamic balance function was measured using the Berg Balance Scale (BBS). Also, the fall index was measured to evaluate the risk of falling. A paired t-test was performed to compare pre- and post-training performance within the groups. One-way ANOVA was performed for comparing the three groups. A post hoc least significant difference (LSD) test was also performed. Results: The results of the LOS showed a significant difference after training in the EGI and EGII groups (p<0.05). As a result of the difference between the three groups, there was a significant difference after training (p<0.05). The results of the BBS showed a significant difference after training in the EGI group (p<0.05). As a result of the difference between the three groups, there was a significant difference after training (p<0.05). Conclusion: Visual cue deprivation balance training applying head control feedback is effective in improving the dynamic balance function in older people. It is also necessary to constantly maintain the head orientation by feedback and to properly control the head movement.

• 대한물리의학회지
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• 제17권4호
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• pp.93-101
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• 2022

PURPOSE: This study sought to investigate the effects of treadmill gait training combined with a thoracic mobility exercise on gait and balance in patients with stroke. METHODS: In this single-blinded, randomized, controlled, comparative study, a total of 20 patients at a rehabilitation hospital who had suffered a hemiplegic stroke were randomly assigned to the experimental group (treadmill gait training combined with a thoracic mobility exercise, n = 11) or control group (treadmill gait training without the thoracic mobility exercise, n = 9). All the participants underwent comprehensive rehabilitation therapy (5 × /week for 4 weeks). Additionally, the experimental group underwent 20 min of treadmill gait training combined with 10 min of a thoracic mobility exercise (3 × / week for 4 weeks) and the control group underwent the former but not the latter. Gait and balance were measured before and after the 4-week training. RESULTS: Significant improvements were observed in the 10-m walking test (10 MWT), timed up-and-go (TUG) test, center of pressure (COP) velocity, and COP length in the experimental group (p < .05). This group also showed a larger decrease in the 10 MWT and COP velocity than the control group (10 MWT, -3.02 sec vs. -1.68 sec, p < .05; COP velocity, -.07 mm/sec vs. .08 mm/sec, p < .05). CONCLUSION: Treadmill gait training, combined with the thoracic mobility exercise, could be effective in improving the gait and balance of stroke patients. It could also be more effective in improving walking speed and static balance than the treadmill gait training alone.

• 한국지반환경공학회 논문집
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• 제22권12호
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• pp.71-77
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• 2021

국내의 공용 중인 도로의 연장의 증가와 함께 유지보수 비용 및 교통혼잡비용도 함께 증가하고 있는 추세이다. 도로의 유지보수 비용 및 소요시간의 단축을 위하여 기존에 지속가능한 장수명 모듈러 도로시스템이 제안되었다. 본 연구에서는 제안된 시스템의 하부구조인 맞춤형 지지모듈의 설계 및 성능평가를 수행하였다. 하중을 결정하고 형태가 다른 2가지의 맞춤형(Cross-Beam 형태) 지지모듈을 설계, 제작하였다. 제작한 맞춤형 지지모듈을 시공하고 성능이 더 우수한 형태의 지지모듈 선정을 위하여 정하중재하 시험을 진행하였다. 하중재하 시험 결과 두가지 형태의 맞춤형 지지모듈에서 측정된 최대 토압은약 158kPa 차이가 났으며, 최대 침하량은 약 0.032mm의 차이가 나타났다. 이러한 결과를 바탕으로 하부곡선형 Cross-Beam 형태의 맞춤형 지지모듈의 성능이 더 우수한 것으로 판단된다.

• Clinical and Experimental Pediatrics
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• 제65권3호
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• pp.142-149
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• 2022

Background: Individuals with Down syndrome present with several impairments such as hypotonia, ligament laxity, decreased muscle strength, insufficient muscular cocontraction, inadequate postural control, and disturbed proprioception. These factors are responsible for the developmental challenges faced by children with Down syndrome. These individuals also present with balance dysfunctions. Purpose: This systematic review aims to describe the motor dysfunction and balance impairments in children and adolescents with Down syndrome. Methods: We searched the Scopus, ScienceDirect, MEDLINE, Wiley, and EBSCO databases for observational studies evaluating the motor abilities and balance performance in individuals with Down syndrome. The review was registered on PROSPERO. Results: A total of 1,096 articles were retrieved; after careful screening and scrutinizing against the inclusion and exclusion criteria, 10 articles were included in the review. Overall, the children and adolescents with Down syndrome showed delays and dysfunction in performing various activities such as sitting, pulling to stand, standing, and walking. They also presented with compensatory mechanisms to maintain their equilibrium in static and dynamic activities. Conclusion: The motor development of children with Down syndrome is significantly delayed due to structural differences in the brain. These individuals have inefficient compensatory strategies like increasing step width, increasing frequency of mediolateral center of pressure displacement, decreasing anteroposterior displacement, increasing trunk stiffness, and increasing posterior trunk displacement to maintain equilibrium. Down syndrome presents with interindividual variations; therefore, a thorough evaluation is required before a structured intervention is developed to improve motor and balance dysfunction.

• 한국지반공학회논문집
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• 제23권3호
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• pp.141-147
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• 2007

말뚝의 동적 응답 해석을 위한 다양한 방법들이 개발되어 있으며, 이 중에서 비선형 스프링, p-y 곡선을 이용하여 지반-말뚝 상호작용을 고려하는 방법이 널리 사용되고 있다. 그러나, 현재 사용되는 동적 p-y 곡선은 정적 또는 주기 하중에 의한 횡방향 재하 시험에 의해 개발되었다. 또한, p-y 곡선에 scaling factor를 도입하여 액상화에 의한 지반-말뚝 상호작용의 영향을 모사하고자 하는 시도가 이루어져 왔으나, 지금까지 정확한 scaling factor를 산정하지 못하고 있는 실정이다. 이에 본 연구에서는 Ig 진동대 실험으로부터 구한 말뚝 주변 지반의 과잉간극수압과 지반-말뚝 시스템의 고유진동수 관계 및 수치해석으로부터 구한 말뚝 주변 지반의 탄성계수의 변화와 지반-말뚝 시스템의 고유진동수 관계로부터, 말뚝 주변 지반의 탄성계수의 변화로 표현되는 p-y 곡선의 scaling factor를 구하였다. 그 결과, scaling factor는 과잉간극수압비에 따른 지수 함수의 형태로 나타났다.

• 대한토목학회논문집
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• 제29권1C호
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• pp.21-31
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• 2009

기존의 연구에서 이미 경량성토재료로서 적용된 바 있는 저회(Bottom Ash), 폐타이어-흙 혼합토의 성능을 토대로 하여, 전통적인 성토재료인 흙 대신 저회를 활용하는 새로운 경량성토재료를 제안한 바 있다. 이어서 이 연구에서는 저회-폐타이어 혼합토의 경량성토재료로서의 적용성을 평가하기 위해 현장다짐시험과 실대형 성토 모형실험을 수행하여 기존의 성토재료인 풍화토만으로 조성된 성토구조물과 저회-폐타이어 혼합토로 조성한 성토구조물에 대한 침하, 토압, 지지력, 진동저감효과 등을 평가하였다. 그 결과 토압 및 진동은 저감되는 효과를 보였으며, 정동적 하중에 따른 침하거동은 두 재료(풍화토 단면, 저회-폐타이어 혼합재료)에서 유사하게 평가되었다.

• Geomechanics and Engineering
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• 제37권3호
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• pp.293-306
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• 2024

Influenced by the alternating effects of dynamic and static pressure during the mining process of close range coal seams, the surrounding rock support of cross mining roadway is difficult and the deformation mechanism is complex, which has become an important problem affecting the safe and efficient production of coal mines. The paper takes the inclined longwall mining of the 10304 working face of Zhongheng coal mine as the engineering background, analyzes the key strata fracture mechanism of the large inclined right-angle trapezoidal mining field, explores the stress distribution characteristics and transmission law of the surrounding rock of the roadway affected by the mining of the inclined coal seam, and proposes a segmented and hierarchical support method for the cross mining roadway affected by the mining of the close range coal seam group. The research results indicate that based on the derived expressions for shear and tensile fracture of key strata, the ultimate pushing distance and ultimate suspended area of a right angle trapezoidal mining area can be calculated and obtained. Within the cross mining section, along the horizontal direction of the coal wall of the working face, the peak shear stress is located near the middle of the boundary. The cracks on the floor of the cross mining roadway gradually develop in an elliptical funnel shape from the shallow to the deep. The dual coupling support system composed of active anchor rod support and passive U-shaped steel shed support proposed in this article achieves effective control of the stability of cross mining roadways, which achieves effective control of floor by coupling active support and preventive passive support to improve the strength of the surrounding rock itself. The research results are of great significance for guiding the layout, support control, and safe mining of cross mining roadways, and to some extent, can further enrich and improve the relevant theories of roof movement and control.

• 대한물리치료과학회지
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• 제31권1호
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• pp.1-15
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• 2024

Background: This study was conducted to apply active release techniques to male youth basketball players to help improve physical development and damage prevention and improve performance through improved balance and functional movement. Design: Randomized control trial. Methods: The subjects included 33 youth basketball players who were randomly assigned to the experimental group (n=17) and the control group (n=16). For the experimental group, the active release technique was applied to the hip muscles, calf muscles, posterior thigh muscles based on the distribution of injuries surveyed in youth basketball players in the Korean Basksetball League. The Y-balance test and the functional reach test (FRT) were used to assess balance and the Functional Movement Screen (FMS) was used to assess functional movement. Interventions were conducted twice a week for 4 weeks at 40 minutes per session. The experimental group was the active release technique group, and static stretching, a common exercise therapy technique, and self-myofascial release using a foam roller were applied for 20 minutes. The control group received general exercise therapy and placebo active release technique. The placebo active release technique applies pressure only. results:The experimental group showed a greater improvement in balance, as evidenced by the FRT, compared to the control group, which received general exercise treatment. However, there was no statistically significant difference in improvement between the 2 groups. In the case of the experimental group, the difference in the Y balance test before and after the intervention was larger than that of the control group, but there was no statistically significant difference. Significant improvement was found in functional movement, as evidence by the FMS, for the trunk stability test (p < 0.05), in-line lunge test (p < 0.05), rotational stability test (p < 0.05), total score (p < 0.05). Conclusion: In this study, the active release technique improved the balance and functional movement of young basketball players more than general exercise therapy. The application of the active release technique is therefore expected to assist in physical development, prevent damage, and improve the performance of youth basketball players.