• 한국방재학회 논문집
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• 제4권2호
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• pp.13-18
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• 2004

본 연구는 유한차분법을 이용하며 변위 및 응력에 1차 적인 영향을 주는 매개변수를 구축하였으며 이를 이용하여 기존 원심모형 실험값 중 천단변위, 내공변위 결과를 수치해석상결과와 비교하였고, 모형실험에서 다양하게 구현할 수 없었던 응력, 라이닝 설치의 시간적 효과를 고려하여 강성의 차이에 따른 매개변수연구를 수행하였다. 연구결과 3차원 해석을 통한 대구경강관 그라우팅의 보강물성치는 원지반 강성의 8배인 E=4,000tf/m2일때 개략적인 지반보강효과가 발현되는 것으로 확인되었다.

• 한국안전학회지
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• 제33권5호
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• pp.164-169
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• 2018

A detailed fatigue evaluation procedure was developed to mitigate the excessive conservativeness of the conventional environmental fatigue evaluation method for the pressurizer spray line elbow of domestic new nuclear power plants. The pressurizer spray line is made of austenitic stainless steel, which is relatively sensitive to the environmentally assisted fatigue, and has a low degree of design margin in terms of environmentally assisted fatigue due to the thermal stratification phenomenon on the pipe cross section as a whole or locally. In this study, to meet the environmental fatigue design requirements of the pressurizer spray line elbow, the new environmental fatigue evaluation has been performed, which used the ASME Code NB-3200-based detailed fatigue analysis and the environmental fatigue correction factor instead of the existing NB-3600 evaluation method. As a result, the design requirements for environmentally assisted fatigue were met in all parts of the pressurizer spray line elbow including the fatigue weakened zones by thermal stratification.

• 공학논문집
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• 제6권1호
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• pp.83-96
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• 2004

강판파일로 지지되고 있는 미니 교대하부에, 압성토의 제거에 따른 교대의 안정성을 확보하기 위한 방법으로서 쏘일네일링 공법을 채택하였다. 네일벽체에 각종 계측기를 매설하여 벽체의 거동을 추적하였다. 또한 3차원 유한요소해석기법을 이용하여 쏘일네일 벽체와 기존 구조물사이의 상호영향과 관련된 벽체의 거동을 분석하였다. 압성토의 순차적 제거와 네일타설 등의 전 축조 시퀀스를 모델링 할 수 있는 기법을 개발하였으며 개발된 시뮬레이션 기법의 타당성을 검증하기 위해 현장에 축조된 실물 계측데이터를 이용하여 보정하였고, 압성토의 제거와 네일타설이 기존 파일의 축하중 및 휨모멘트에 미치는 영향과 네일 인장력의 변화와의 상관관계 등, 설계시 고려되어야 할 몇 가지 주요한 사항에 대한 해석결과를 구할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.351-359
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• 2010

Large PHC piles with a diameter of 1,000mm or larger were recently introduced for the first time in Korea. This paper presents full-scale static and dynamic pile load tests performed on two 1,000mm PHC piles and two composite piles with steel pipe piles of the same diameter in the upper portion, installed by driving and pre-boring. The objectives of the tests include evaluating pile drivability, load-settlement relation, allowable bearing capacity, and the stability of mechanical splicing element for the composite pile(a.k.a. non-welding joint). The performance of the large diameter PHC piles were thought to be satisfactory compared to that of middle sized PHC piles with a long history of successful applications in the domestic and foreign markets.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.293-298
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• 1999

The crack of concrete induced by the heat of hydration is a serious problem, particularly in concrete structures such as underground box structure, mat-slab of nuclear reactor buildings, dams or large footings, foundations of high rise buildings, etc.. As a result of the temperature rise and restriction condition of foundation, the thermal stress which may induce the cracks can occur. Therefore the various techniques of the thermal stress control in massive concrete have been widely used. One of them is prediction of the thermal stress, besides low-heat cement which mitigates the temperature rise, pre-cooling which lowers the initial temperature of fresh concrete with ice flake, pipe cooling which cools the temperature of concrete with flowing water, design change which considers steel bar reinforcement, operation control and so on. The objective of this paper is largely two folded. Firstly we introduce the cracks control technique by employing low-heat cement mix and thermal stress analysis. Secondly it show the application condition of the cracks control technique like the subway structure in Seoul.

• 한국공간구조학회논문집
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• 제5권4호
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• pp.61-70
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• 2005

본 논문은 SUMT와 유전자알고리즘을 근거한 연속 및 이산최적설계 알고리즘에 의한 최적설계 프로그램을 개발하였다. 본 연구의 최적설계는 단동온실 구조물의 단면 연속 및 이산 최적설계가 각각 동시에 수행된다. 본 연구에서 목적함수는 구조물의 중량이고, 제약조건식은 한계상태설계기준에 대한 설계 제한식이다. 설계변수는 원형단면의 직경과 두께이다. 그리고 본 연구의 SUMT 및 유전자 알고리즘에 의한 연속 및 이산화 최적설계 프로그램의 적용을 위해 설계 예를 들었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.536-545
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• 2006

In this study the behavior of piles with an extended head is invested experimentally using reduced-scale model tests. Special attention is given to verifying the increase of end bearing capacity of piles with spreading head. Model piles and extended head plates made of steel pipe were used in this study. Bearing capacity of piles is regarded as only end bearing capacity. The study analyzed the tendency of single and group pile of bearing capacity compared with the existing PHC pile, and examined optimum effect of extended head.

• 한국해양공학회지
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• 제24권4호
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• pp.32-37
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• 2010

This study presents the attenuation characteristics of the first guided longitudinal wave mode propagating in water-filled, buried steel pipes in order to investigate the effects of soil saturation and compaction on the attenuation patterns. For numerical calculation of attenuation, 10 different combinations of S-wave velocity, P-wave velocity, and soil densities were considered. From the attenuation dispersion curves, which were obtained using Disperse software, we determined that the attenuation decreases as saturation increases, whereas it increases as compaction increases. Over the frequency range from 0.2 to 0.4 MHz, the first longitudinal wave mode has attenuations that are relatively lower than for other ranges, is faster than the first flexural wave mode, and is sensitive to defects aligned in the axial direction. Hence, the first longitudinal wave mode over the mentioned frequency range would be the proper choice for long-range buried pipelines that transport water.

• 대한기계학회논문집
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• 제18권6호
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• pp.1551-1558
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• 1994

An experiment was conducted to investigate whether an equation of heat transfer coefficient derived form energy equation of two-phase plug flow can be actually applied to the industrial field. The heat is constantly transfered to the sand beds from the wall of heat exchanger while the sand moves down through cylindrical heat exchanger by gravity from feed hooper. To increase heat transfer, turbulators such as glass ball and steel pipe packings were used. In addition, the experiment in the case of fluidizing the sand beds was also carried out. The temperatures of the sand beds and the wall were measured along the heat exchanger axis. The density and porosity of the sand beds were also measured. The deviations of the mean velocity of sands from the velocity on the wall surface because of the slip conditions on the wall were negligible (within 3%). The heat transfer coefficients when the turbulators were used and when the sand beds were fluidized were found to be much greater than those of the plain plug flow.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.776-781
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• 2001

To enhance thermal efficiency of thermal facility through recovery of low and medium temperature waste heat, 1MW organic Rankine cycle system was designed and developed. The exhaust gases of $175^{\circ}C$ at two 100MW power plants in pohang steel works were selected as the representative of low and medium temperature waste heat in industrial process for the heat source of the organic Rankine cycle system. HCFC-123, a kind of harmless refrigerant, was chosen as the working fluid for Rankine cycle. The organic Rankine cycle system with selected exhaust gases and working fluid was designed and constructed. From the operation, it was confirmed that the organic Rankine cycle system is available for low and medium temperature waste heat recovery in industrial process. The optimum operating manuals, such as heat-up of hot water, turbine start-up, and the process of electric power generation, were derived. However, electric power generated was not 1MW as designed but only 670kW. It is due to deficiency of pump capacity for supply of HCFC-123. So it is necessary to increase the pump capacity or to decrease the pressure loss in pipe for more improved HCFC-123 supply.