• 한국신뢰성학회지:신뢰성응용연구
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• 제16권2호
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• pp.125-133
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• 2016

Purpose: The purpose of this study is to evaluate durability of platform safety step system in railway. Method: We performed finite element analysis & durability analysis of platform safety step system with VPD (Virtual Product Development) techniques and examined the durability standard & qualification life through the rig test during no failure test time in reliability qualification test. We continued to test 1 million cycles in KRS (Korea Railway Standard) for system's robust design performance. Result: FEM analysis results are 14.9MPa & 14.7MPa of pin-joint, pivot and durability analysis result is above 1 million cycles. we calculated theoretically no failure test time 855,000 cycles and through the 1 million cycles durability rig test in KRS standard we confirmed product quality. Conclusion: This platform safety step system was designed very safe in terms of a mechanical strength & durability.

• 대한물리의학회지
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• 제9권3호
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• pp.285-291
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• 2014

PURPOSE: The purpose of this study was to propose clinical criteria to differentiate patients who are able to perform the step-through-step gait pattern in chronic stroke patients. METHODS: Sixty patients with chronic stroke patients participated this study. To differentiate patients who could perform the step-through-step gait pattern, age, gender, and causes of stroke were noted, a Chedoke-McMaster (CM) damage list, Fugl-Meyer (FM) assessment scales and the Berg Balance Scale (BBS) were determined. A 10 meter gait test and Timed Up and Go (TUG) test were conducted to determine the differences in gait speed and dynamic balance between patients walking with or without canes in the step-through-step gait pattern group. RESULTS: There was no significant statistical difference in age, gender, and stroke type between all subjects. There were significant differences in the CM scale for postural and lower extremities, and FM scale for lower extremities and BBS. The dynamic balance ability and gait speed showed significant differences between the subjects in the step-through-step gait pattern with or without a cane during gait. CONCLUSION: CM and FM scales for the lower extremities and postural control, as well as BBS scales, can be used as criteria to differentiate patients who are able to perform the step-through-step gait pattern. These results can also be used to provide beneficial information to patients that are walking with canes.

• International Journal of Reliability and Applications
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• 제17권1호
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• pp.21-49
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• 2016

Many mechanical, electrical and electronic products have more than one performance characteristics (PCs). For example the performance degradation of rubidium discharge lamps can be characterized by the rubidium consumption or the decreasing intensity the lamp. The product may degrade due to all the PCs which may be independent or dependent. This paper deals with the design of optimal bivariate step-stress partially accelerated degradation test (PADT) with degradation paths modelled by gamma process. The dependency between PCs has been modelled through Frank copula function. In partial step-stress loading, the unit is tested at usual stress for some time, and then the stress is accelerated. This helps in preventing over-stressing of the test specimens. Failure occurs when the performance characteristic crosses the critical value the first time. Under the constraint of total experimental cost, the optimal test duration and the optimal number of inspections at each intermediate stress level are obtained using variance optimality criterion.

• 한국CDE학회논문집
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• 제9권1호
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• pp.11-18
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• 2004

CAD systems have been developed with network technology and it is needed to exchange product data among them. STEP becomes world-wide international standard to exchange CAD data among various heterogeneous CAD systems in manufacturing industrial fields. We report results to test errors that can happen when exchanging STEP files of product model through the STEP translator of different commercial CAD systems. Also the tests of Korean Character, Hangul, have been carried out. And also we report the STEP rallies held twice in Korea and several rounds abroad, and their testing results are shown as tables and graphs. The tested results can be used for exchanging product models to the next domestic STEP Rally and extended to Northeastem Asian STEP rally by steadily contacting with the organizations for Asian STEP centers such as JSTEP(Japan) and CSTEP(China). Finally we expect that the result can be used to specify STEP standardization in the field of managing product data.

• Journal of Ginseng Research
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• 제20권3호
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• pp.226-232
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• 1996

This study was performed to investigate the effect of red ginseng extract including some vitamin B groups as test drug on learning and memory in mice. Single and repeated administrations of the test drug improved the acquisition and the process of consolidation in the tests using step-through and step-down apparatus, indicating this test drug improved learning and memory. However, the test drug did not improve scopolamine-induced amnesia. These results suggest that test drug may be useful as a nootropic agent.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.490-495
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• 2009

In this study, estimate solution of ultimate axial capacity for axial loaded pile is proposed using step-wised shape. This is verified for effective appling on realistic factor by calibration chamber tests. Estimation method of ultimate axial capacity in this study is verified by calibration chamber test. The results of ultimate axial capacity through this proposed method have sufficiently low standard derivations and COVs. Also, this is verified through test that method is similarly resulted with measured values.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.768-779
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• 1995

This study was performed to investigate the effect of root canal shaping techniques on the change of the shape of prepared root canal. 40 mesiobuccal canals of recently extracted mandibular 1st and 2nd molars were divided into 4 groups and shaped by step-down/balanced force technique, step-down/step-back technique, step-back technique and conventional technique respectively. The change of the shape of root canal was traced by superimposing the radiographs obtained before and after shaping of each root canal. The results were as follows. 1. By the experimented techniques except conventional technique, the root canals were more shaped in convex side of apical area and in concave side of most curved and coronal area than in the other sides(P<0.05). By conventional technique, the root canals were more shaped in convex side than in convave side from apex to orifice(P<0.05). 2. By step-down/balanced force technique, the cancave sides at C and D points of proximal view and C point of clinical view were more shaped than the convex side(P<0.05). Through the entire canal, the concave side was more shaped than the convex side in proximal view(P<0.01). But there was no statistical difference between both sides in clinical view. 3. By step-down/step-back technique, the change of root canal shape was not statistically different in concave and convex sides at each point of both views(P>0.05). And through the entire canal in proximal view, there was no statistical difference in shaping percentage between both sides. But through the entire canal in clinical view, the concave side was more shaped than the convex side(P<0.1). 4. By step-back technique, the convex side at B point of clinical more shaped than the other sides(P<0.05). Through the entire canal in proximal and clinical views, there was no statistical difference in shaping percentage between both sides. 5. Comparing the total shaping percentage among techniques, that in conventional technique was the greatest numerically, and followed by the percentages in step-down/step-back, step-down/balanced force and step-back technique. But, in proximal view, shaping percentages were not statistically different among techniques(P>0.05, ANOVA test). In clinical view, shaping percentages in step-back and conventional techniques were statistically different(P<0.01, ANOVA test). * Proximal view: radiograph taken in mesiodistal direction. * Clincal view: radiograph taken in faciolingual direction. A point : 1mm point from radiographic apex B point : center point between A and C points C point : most curved point of root canal D point : center point between C point and canal oriffice.

• Korean Chemical Engineering Research
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• 제58권2호
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• pp.190-196
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• 2020

공정 실험을 통하여 공정 동특성 모델을 얻는 과정은 제어시스템 설계에 있어 시간과 비용이 드는 매우 중요한 과정이다. 이를 위한 계단응답은 공정의 동특성을 이해하고 동특성 모델을 얻는 데 사용되는 오래된 하나의 정형화된 공정응답이다. 계단응답에 근거한 방법에서는 공정입력에 계단 변화를 주었을 때 나타나는 공정출력을 측정하여야 하는데, open-loop 상태로 장시간 운전해야 하는 것이 단점으로 지적된다. 이 단점을 완화하기 위하여 시간최적제어 기법을 이용하는 계단응답을 얻는 시간을 최소화 하는 방법이 제안되어 있다. 이 최적화에는 반복 계산이 필요한데, 여기서는 반복 계산이 필요 없는 방법을 제안한다. 계단응답을 위한 시간이 획기적으로 줄어드는 것을 보여주는 모사 결과들을 얻었으며, 이 방법을 제어기 자동튜닝에 응용하여 이 자동튜닝에 널리 채택되고 있는 relay feedback 자동튜닝과 비교한 모사 결과들을 제시하였다.

• 한국콘텐츠학회논문지
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• 제21권6호
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• pp.318-326
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• 2021

본 연구는 고령화 및 저출산에 따라 보건의료분야의 만성질환의 증가 및 전문 인력부족 등의 문제를 해결하고 효율적인 헬스케어를 제공하고자 VR 콘텐츠를 이용한 신체검사의 효과성을 연구하였다. 이에 본 연구는 HTC VIVE Pro VR과 스틱 컨트롤러를 착용하여 원스톱 VR 콘텐츠 신체검사 시스템을 구현하였다. 시스템은 1단계부터 5단계까지이며, 색각테스트, 기억력테스트, 청력테스트, 반응속도테스트, 순간인지능력테스트의 5단계를 순차적으로 거쳐 최종 신체 나이를 판별하는 솔루션으로 구성된다.또한 본 연구가 개발한 원스톱 VR 콘텐츠 신체검사 시스템에 대해 대전 소재 A 상급종합병원 건강검진센터 및 VR/AR 임상시험 센터에 내원한 정상인을 대상으로 사용자 만족도를 검증한 결과, 전체적인 만족도와 재이용의사가 높게 나타났고, 성별에 따라 5단계 순간인지테스트는 유의한 차이가 있었으며, 연령에 따라서 4단계 반응속도테스트, 5단계 순간인지테스트에서 유의한 차이가 나타났다.

• 한국항공우주학회지
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• 제43권9호
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• pp.814-821
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• 2015

극초소형 위성으로 분류되는 큐브위성 STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project)은 우주기반 핵심기술들의 궤도검증을 주 임무로 2015년 발사를 위해 최종 비행모델의 개발을 완료하였다. 상기 임무를 위해 STEP Cube Lab.은 수동 열제어를 기반으로 최적화된 열제어 설계를 수행하였으며, 수락(acceptance) 수준의 열진공시험을 통해 위성 성능 및 열제어 설계의 검증을 완료하였다. 또한 열평형 시험을 통해 위성 열-수치 모델의 신뢰도 향상을 위한 보정 작업을 수행하였다. 본 논문에서는 STEP Cube Lab. FM의 열진공시험을 통한 일련의 검증 과정에 대해 서술하고자 한다.