• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.86-87
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• 2005

The combustion characteristics of the D.I. diesel engine are largely dependent on the air-fuel ratio and the gas exchange process. The main factors are the shape of combustion chamber, fuel injection system, air flow inside the cylinder, intake air mass flow rate and so forth. Because these factors affect the combustion in a mutual and combined manner, it is very important to clearly understand the correlation of these factors in order to provide the combustion improvement plans. In this paper, we studied the performance and the gas exchange process of marine four-stroke engine using the engine cycle simulation. Also, we predicted briefly turbocharger engine matching.

• 대한본초학회지
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• 제26권1호
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• pp.75-80
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• 2011

Objectives : The aim of the present study is to investigate the hypotensive effect of Samhwangsasim-tang (SHSST), Samigangap-tang (SMGAT) and Bangtan-tang (BTT) in stroke-prone spontaneously hypertensive rats (SHR-SP). Methods : SHR-SP rats were treated with SHSST, SMGAT and BTT at dose of 200 mg/kg/day orally for 5 weeks, respectively. Results : Treatment SHR-SP rats with SMGAT significantly lowered blood pressure but not in the SHSST or BTT treat groups. On the other hand, SHSST, SMGAT and BTT ameliorated endothelium-dependent and independent vascular relaxation in the phenylephrine-precontracted aorta and carotid artery, respectively. Conclusions : These results indicated that SMGAT has an antihypertensive effect and SHSST, SMGAT and BTT improve vascular function in stroke-prone hypertensive rat model, respectively.

• 대한통합의학회지
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• 제3권4호
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• pp.69-78
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• 2015

Purpose: The purpose of this study was to identify whether inclined treadmill gait training with rhythmic auditory simulation (RAS) could improve on balance and gait in stroke patients. Method: Fifteen stroke patients who had agreed with the study were allocated to the group 1(n=5), group 2(n=5), or group 3(n=5). The group 1, group 2 and group 3 performed RAS with inclined treadmill gait training, inclined treadmill gait training and treadmill without incline gait training respectively for 3 weeks (30 minutes per session, 5 times in a week). The balance was assessed using Timed Up & Go (TUG) and Berg Balance Sale (BBS), and the gait was evaluated using 6 Minutes Walking Test (6MWT) and spatio-temporal walking variables as walking speed, cadence, Single Limb Support of affected side(SLS) and Symmetric Index(SI) before and after training. Result: Both the group 1 and group 2 showed significant improvement after training in all variables of balance and gait. The group 3 showed significant improvement in TUG values, 6MWT values, walking speed, cadence and SI. The changes in the group 1 were significantly greater in all dependent variables of balance and gait than those of the group 2 and group 3. The changes in the group 2 were significantly greater in TUG values, BBS scores, 6MWT values, walking speed, and cadence than those of the group 3. Conclusion: The result of this study show inclined treadmill gait training with RAS is more effective to improve balance and gait in stoke patients than inclined treadmill or general treadmill gait training without RAS.

• 융합정보논문지
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• 제9권10호
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• pp.220-226
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• 2019

본 연구는 발바닥 굽힘근에 저주파 치료인 경피신경전기자극과 중주파 치료인 간섭전류가 뇌졸중 환자의 보행 및 발목 관절가동범위에 즉각적인 영향을 미치는지 알고자 한다. 30명의 연구대상자는 경피신경전기자극군과 간섭전류군으로 동일하게 나누어 마비측 장딴지근에 각각 통전하였다. 60분 통전 직후 스마트폰을 이용한 보행 평가와 발등 굽힘 관절가동범위를 측정하였다. 연구결과 두 전기치료 방법 모두 보행속도, 분속수, 발목 관절가동범위에 유의한 증가를 보였다. 두 전기치료 방법 모두 뇌졸중 환자의 보행 및 발목 관절가동범위를 증가시킬 수 있는 중재 방법이었지만 두 전기치료방법 간의 차이는 더 많은 대상자 모집을 통해 확인되어야 할 것이다.

• 한국세라믹학회지
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• 제29권2호
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• pp.136-142
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• 1992

The effects of cyclic stress, frequency and bias-pressure on densification of Al2O3 powder cyclic compaction are investigated. The effect of frequency was not significant on densification of Al2O3 powder under cyclic compaction. The higher the cyclic stress and the lower the bias pressure, the higher densification was achieved. To obtain a higher densification, cyclic compaction was more efficient than 1 stroke compaction. A densification equation was proposed to describe an cyclic time dependent pressure-volume relation for Al2O3 powder under cyclic compaction. This equation was obtained empirically, based on the pressure-volume equation proposed by Cooper and Eaton, the time dependent densification equation by Kim and Suh and experimental data for Al2O3 powder under cyclic compaction. The agreement between the proposed equation and experimental data for Al2O3 powder under cyclic compaction was very good.

• 한국산학기술학회논문지
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• 제13권12호
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• pp.5867-5874
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• 2012

본 연구의 목적은 뇌졸중 환자에서 주관절 각도 변화에 따른 상완이두근(biceps brachii)의 근구조 및 탄성 변화에 관하여 알아보고자 하였다. 연구대상은 주관절 수동 ROM범위가 $10^{\circ}{\sim}90^{\circ}$ 가능하며 MAS(modified Ashworth scale) 1~3등급인 뇌졸중 환자 12명을 대상으로 하였다. 이완(resting) 상태의 건측과 환측 상완이두근의 우모각, 근섬유속길이, 근탄성의 측정은 초음파 영상 촬영장치와 근긴장도 측정기(myotonometer)를 이용하여 주관절을 $10^{\circ}{\sim}90^{\circ}$로 변화시키면서 측정하였다. 본 연구 결과, 환측 상완이두근을 건측과 비교 시 우모각은 신전위치($<40^{\circ}$)에서 큰 값을 나타냈으며(p<.05), 근섬유속길이는 굴곡위치($>20^{\circ}$)에서 짧은 길이를 나타냈으며(p<.05), 근긴장은 신전위치($<50^{\circ}$)에서 전위 값이 낮게 나타나 근긴장이 높아짐을 나타냈다(p<.05). 이렇듯 이완 시 상완이두근의 근구조 및 탄성은 주관절 각도에 의해 영향을 받는다는 것을 알 수 있었다. 본 결과를 뇌졸중 환자의 근구조 변화 및 임상치료의 연구 자료로 사용할 수 있을 것으로 생각된다.

• 한국융합학회논문지
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• 제11권5호
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• pp.87-96
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• 2020

만성 뇌졸중 환자를 대상으로 메타분석 기법을 활용하여 트레드밀 훈련의 융복합적 효과성을 평가하고자 한다. PICOS 기준에 의거하여 문헌을 검색한 후 총 22편의 국내 '뇌졸중', '트레드밀' 관련 연구물을 선정하였다. 메타분석을 위해 CMA 프로그램을 이용하여 효과크기를 산출하였으며, 국내 트레드밀 훈련의 전체 효과크기는 0.661(95%CI: 0.456~0.865)로 중간크기로 유의한 차이가 있었다(p<.05). 트레드밀 훈련의 효과를 족저압(1.147), 하지 근 기능(0.875), 균형(0.664)으로 나누어 효과크기를 비교한 결과, 족저압의 효과크기가 가장 크게 나타났다. 추가로 균형은 하위항목들을 나누어 분석하였고, 균형은 TUG(0.553), BBS(0.760), 정적균형지수(0.654)의 효과크기가 나타났다. 따라서 트레드밀 훈련이 만성 뇌졸중 환자의 삶의 질 향상에 긍정적인 영향을 제공한다. 트레드밀 훈련에 대한 메타분석 연구는 정보, 통신 및 의료기술의 헬스케어 융합을 향한 업계 패러다임의 전환으로 이어질 수 있을 것이다.

• 한국정밀공학회지
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• 제19권12호
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• pp.163-170
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• 2002

The quality of a precision product, in general, relies on the accuracy and precision of its manufacturing and inspection process. In many cases, the level of precision in the manufacturing and inspection system is also dependent on the positioning capability of tool with respect to the work piece in the process. Recently the positioning accuracy level has reached to the level of submicron and long range of motion is required. For example, for 1 GDARM lithography, 20nm accuracy and 300mm stroke needs. This paper refers to the lithography stage especially to fine stage. In this study, for long stroke and high accuracy, the dual servo system is proposed. For the coarse actuator, LDM (Linear DC Motor) is used and for fine one VCM is used. In this study, we propose the new structure of VCM for the fine actuator. It is 3 axis precision positioning stage for an aligner system. After we perform the optimal design of the stage to obtain the maximum force, which is related to the acceleration of the stage to accomplish throughput of product. And we controlled this fine stage with TDC. So we obtained 50nm resolution. So later more works will be done to obtain better accuracy.

• Journal of Mechanical Science and Technology
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• 제19권2호
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• pp.520-528
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• 2005

In this study, a new mathematical dynamic model of displacement sensitive shock absorber (DSSA) is proposed to predict the dynamic characteristics of automotive shock absorber. The performance of shock absorber is directly related to the vehicle behaviors and performance, both for handling and ride comfort. The proposed model of the DSSA has two modes of damping force (i.e. soft and hard) according to the position of piston. In this paper, the performance of the DSSA is analyzed by considering the transient zone for more exact dynamic characteristics. For the mathematical modeling of DSSA, flow continuity equations at the compression and rebound chamber are formulated. And the flow equations at the compression and rebound stroke are formulated, respectively. Also, the flow analysis at the reservoir chamber is carried out. Accordingly, the damping force of the shock absorber is determined by the forces acting on the both side of piston. The analytic result of damping force characteristics are compared with the experimental results to prove the effectiveness. Especially, the effects of displacement sensitive orifice area and the effects of displacement sensitive orifice length on the damping force are observed, respectively. The results reported herein will provide a better understanding of the shock absorber.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.1184-1189
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• 1990

In order to investigate liquid fuel filming over the intake manifold wall, an electrode-type probe has been developed by lines of authors and this probe was employed in a single cylinder two and four-stroke cycle engine and in a four cylinder four-stroke engine operated by neat methanol fuel. The performance of the probe was dependent upon several parameters including the liquid fuel layer thickness, temperature, additive in the fuel, and electric power source (i.e., AC and voltage level) and was independent of other variables such as direction of liquid flow with respect to the probe arrangement. Several new findings from this study may be in order. The flow velocity of the fuel layer in the intake manifold of engine was about (if the air velocity in the steady state operation, the layer thickness of liquid fuel varied in both the circumferential and longitydinal directions. In the transient operation of the engine, the temporal variation of fuel thickness was determined, which clearly suggests that there was difference between fuel/air ratio in the intake manifold and that in the cylinder. The variation was greatly affected by the engine speed, fuel/air ratio and throttle opening. And the variation was also very significant from cylinder to cylinder and it was particularly strong different engine speeds and throttle opening.