• 한국구조물진단유지관리공학회 논문집
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• 제6권2호
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• pp.175-182
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• 2002

The cement injection technology on the purpose of ground reinforcement and cut-off has been used in construction sites until now. However, recently it is applied to prevent leakage of underground structure. In this study, applicability of the back side waterproof grouting method was verified through performing field model tests and reviewing case histories. From the results of this study, injection shape of the back side waterproof grouting method was appeared to be root type, and waterproof effect by injection of cement grout material was excellent because grout material infiltrated into boundary between wall of structure and back side ground to be waterproof layer. Components influencing infiltration of injection material are type of soil and degree of compaction. For effective injection, injection pressure has to vary gradually from high pressure to low pessure and small quantity of injection material has to be injected for long times. Also, spacing of injection hole must be designed considering condition of back side ground, injection area, W/C ratio, the number of injection and injection pattern properly.

• 한국지반공학회논문집
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• 제19권1호
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• pp.111-120
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• 2003

본 연구에서는 점성토지반의 침하량 평가에 보다 적합한 새로운 응력경로시험을 소개하였다. 새로운 시험기법에서는 배압평형과정을 채택함으로써 특정 응력경로상의 모든 점에 대응하는 변형특성을 하나의 시험을 통해 파악할 수 있다. 따라서, 제안된 시험기법을 적용하는 경우, 응력경로법의 실용적인 적용을 위해 필요한 지반의 전반적인 변형거동을 몇 개의 시험만으로 예측할 수 있으며 나아가 기존의 시험기법으로는 수행이 불가능했던 이방적 압밀응력 경로에 대한 변형거동의 평가 역시 실험적으로 가능해진다. 이와 함께 본 연구에서는 성형 카올리나이트 시료에 대해 다양한 응력경로시험을 수행하여 제안된 시험기법의 실험적 적용성을 확인하였으며, 그 결과를 활용하여 전반적인 변형거동과 침하량을 평가하는 실제 과정을 제시하였다.

• 설비공학논문집
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• 제10권6호
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• pp.683-694
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• 1998

The application of hydrocarbon refrigerants in a hermetic reciprocating compressor for refrigerator is investigated. The selected refrigerants are isobutane(R600a), propane(R290), R12, binary mixture of R600a/R290, and OS-21CII. Both theoretical and experimental investigations have been performed for the selected refrigerants. The test results of hydrocarbon refrigerants have been compared to the traditional refrigerant(R12). The results show that hydrocarbon refrigerants(HC-Blend, OS-21C II) are very good alternatives in the refrigeration system for R12.

• 설비공학논문집
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• 제11권2호
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• pp.262-269
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• 1999

The application of hydrocarbon refrigerant mixtures in a hermetic reciprocating compressor for dehumidifier is investigated. The selected refrigerants are R12, R134a, HC-Blend (R290/R600a), CX(R152a/R600a) and OS-l2a. Both theoretical and experimental investigations have been performed for the selected refrigerants. The test results of hydrocarbon refrigerants have been compared to traditional refrigerant(R12) and R134a. The results show that hydrocarbon refrigerant mixtures(HC-Blend, CX and OS-l2a) are very good alternatives in the refrigeration system for R12 and R134a.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.107-114
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• 2003

There are many problems in the prediction of dynamic behaviors of saturated soils because undrained excess pore water pressure builds up and then the strain softening behavior is occurred simultaneously. A few analytical constitutive models based on the effective stress concept have been proposed but most models hardly predict the excess pore water pressure and strain softening behaviors correctly In this study, the disturbed state concept (DSC) model proposed by Dr, Desai was modified to predict the saturated soil behaviors under the dynamic loads. Also, back-prediction program was developed for verification of modified DSC model. Cyclic triaxial tests were carried out to determine DSC parameters and test result was compared with the result of back-prediction. Through this research, it is proved that the proposed model based on the modified disturbed state concept can predict the realistic soil dynamic characteristics such as stress degradation and strain softening behavior according to dynamic process of excess pore water pressure.

• 한국유체기계학회 논문집
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• 제7권5호
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• pp.29-35
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• 2004

The turbine efficiency is an important factor in power plant, and accurate evaluation of steam turbine performance is the key issue in turbo machinery industry. The difficulty of evaluating the steam turbine performance due to its high steam temperature and pressure environment makes the most steam turbine tests to be replaced by air similarity test. This paper presents how to decide the similarity conditions of the steam turbine test and describes its limitations and assumptions. The test facility was developed and arranged to conduct an air similarity turbine performance test with various inlet pressure, temperature and mass flow rate. The eddy-current type dynamometer measures the turbine-generated shaft power and controls the rotating speed. Pressure ratio of turbine can be controled by back pressure control valve. To verify its test results, uncertainty analysis was performed and relative uncertainty of turbine efficiency was obtained.

• 한국지반공학회논문집
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• 제28권12호
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• pp.99-110
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• 2012

지반굴착을 위해서 적용되는 흙막이공법은 앵커, 네일, 버팀보 등과 같은 지보재를 사용하게 되며, 지보재 설치에 시간적, 경제적 문제와 건설되는 구조물에도 결함을 야기하는 등의 문제를 안고 있다. 본 연구에서 제안된 지주식 흙막이 공법은 전면지주와 배면지주를 경사로 설치하여 일체화시킨 가시설 공법으로, 배면지주의 설치로 인해 전면지주에 작용하는 토압을 효과적으로 분산시켜 가시설의 구조적인 안정성을 증대시켰다. 본 연구에서는 실내모형실험을 통해 전면지주와 배면지주의 설치각도, 재료강성 등을 달리하여 지주식 흙막이 공법의 안정성을 확인하였으며, 실내 모형실험 결과를 이용하여 배면지주 설치로 인한 전면지주에 작용되는 토압감소효과를 분석하였다. 실험결과 배면지주의 설치로 인해 전면지주에 작용되는 토압감소 및 변위억제 효과는 상당히 큰 것으로 평가되었으며, 본 실험을 통해 지주식 흙막이 공법의 안정성이 증명되었다. 또한 랜킨토압이론을 이용하여 토압감소율을 정량적으로 분석하였다.

• Wind and Structures
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• 제30권3호
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• pp.289-298
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• 2020

Gusts generated by downburst have caused a great variety of structural damages in many regions around the world. It is of great significance to accurately evaluate the downburst-induced wind load on high-rise building for the wind resistance design. The main objective of this paper is to propose a computational modeling approach which can satisfactorily predict the mean and fluctuating wind pressure coefficients induced by downburst on high-rise building surfaces. In this study, using an impinging jet to simulate downburst-like wind, and simultaneous pressure measurements are obtained on a high-rise building model at different radial locations. The model test data are used as the database for developing back propagation neural network (BPNN) models. Comparisons between the BPNN prediction results and those from impinging jet test demonstrate that the BPNN-based method can satisfactorily and efficiently predict the downburst-induced wind pressure coefficients on single and overall surfaces of high-rise building at various radial locations.

• 한국자동차공학회논문집
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• 제21권4호
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• pp.153-158
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• 2013

The purpose of this study is to investigate the performance characteristics of the counterflow exhaust heat recovery device for the applied gasoline engines. The EHRS device is installed behind the catalyst. This study investigates the engine warm-up characteristic, the exhaust noise characteristic, the back-pressure characteristic. The engine warm-up characteristics is (load 0%, load 10%, load 20%) in (idle, 1000rpm, 1500rpm, 2000rpm, 2500rpm) conditions by measuring the time it warmed up, coolant temperature ($25^{\circ}C{\sim}80^{\circ}C$) until the performance evaluation is performed. The wide open throttle and the coast down the exhaust noise and the back-pressure characteristic experiment repeated twice. The test conditions is 950rpm~6,050rpm proceed experiment repeated 3-5 times. Load 0% idle conditions except the results improved engine warm-up characteristics. The exhaust noise obtain similar results the BASE+EHRS W/O_FRT_MUFF with BASE and back-pressure to obtain similar results BASE+EHRS W/O_FRT_ MUFF with BASE+EHRS.

• 한국지반공학회논문집
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• 제19권5호
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• pp.7-14
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• 2003

본 연구의 목적은 계측변위를 이용한 흙막이 벽체의 역해석시 예기치 못한 하중으로 인해 발생한 이상변위의 누적에 의한 오차를 최소화할 수 있는 기법을 개발하는 것이다. 이를 위해 단계별 변위증분으로 목적함수를 구성하고, 목적함수를 최소화시키는 최적화기법으로 직접탐색법중 유용방향법에 의한 순차선형계획법을 도입하여 역해석 프로그램을 개발하였다. 또한, 모형토조실험을 실시하여 측정된 실제변위와 예측변위를 비교$.$분석함으로써 개발된 역해석 프로그램의 신뢰성을 검증하였다.