• 한국초전도ㆍ저온공학회논문지
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• 제12권2호
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• pp.25-28
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• 2010

A cooldown time is one of the major factors in many cryocooler applications, especially for the design of conduction-cooled superconducting apparatus. The estimation of cooldown seeks the elapsed time to cool thermal object by a cryocooler during initial cooldown process. This procedure includes the dimension of cold mass, heat transfer analysis for cryogenic load and available refrigerating capacity of a cryocooler. This method is applied to the specific cooling system for a 3 Tesla superconducting magnet cooled by a two-stage GM cryocooler. The result is compared with that of experiment, showing that the results of proposed method have a good agreement with experiments during initial cooling of superconducting magnet.

• 대한토목학회논문집
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• 제26권5D호
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• pp.821-829
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• 2006

교통하중은 포장 설계 및 해석에서 가장 중요한 입력 변수로서 포장 파손의 주요 원인이 된다. 따라서 정확한 포장 설계 및 해석을 위해서는 적절한 교통하중 정량화가 선행되어야 한다. 전통적으로 교통하중은 혼합된 교통흐름을 설계목적의 하나의 값으로 변환시켜주는 ESALs 관점에서 추정되어왔으나 이는 AASHO 도로 테스트를 통해 도출된 지극히 경험적인 값으로 전 노선망에 대해 평균적인 계수로 적용하기에는 한계가 있다. 이러한 등가단축하중계수의 문제점을 해결하기 위해 선진국에서는 역학적 개념을 도입한 많은 연구를 진행한 결과 역학적-경험적 설계법(Mechanistic-Empirical Design)에 적용할 수 있는 축하중 분포(Axle Load Spectra)를 이용한 교통하중 정량화 방안을 수립하였다. 본 논문에서는 일반국도에 설치 운영되고 있는 WIM 시스템을 통해 수집된 화물차 하중 데이터를 이용하여 축하중 분포 특성(Axle Load Spectra)을 이해하고 혼합정규분포함수에 기초한 축 형태별 하중 분포 모형식을 제시하였으며, 이를 기존 하중 분포 모형과 비교 평가하였다. 본 논문에서 제시한 화물차 축하중 분포 특성 및 축하중 분포 모형식은 향후 일반국도 및 고속도로의 포장 설계법 개발을 위한 교통하중 정량화 방안 수립 시, 과적 차량 단속 정책 수립 시, 도로 유지관리를 위한 계획 수립 시 기초자료로써 활용가능하다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.479-486
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• 2004

The purpose of this study is to practical use with increase safety, usablility and economical. In this study, the property of fatigue behavior was tested by comparing reinforced concrete and steel fiber reinforced concrete. The basic test, the static test and fatigue test were used as the research methods. Basic on the test, the material compressive strength test and split tensile strength test ware conducted 7 days and 28 days after the concrete was poured. In the static test, there ware four types of experimental variables of the steel fiber mixing ratio : 0.00%, 0.75%, 1.00%, and 1.25%. The ultimate load initial diagonal tension crack, and initial load of flexural cracking were all observed by static test. A methodology for the probabilistic assement of steel fiber reinforced concrete(SFRC) which takes into account material variability, confinement model uncertainty and the uncertainty in local and globa failure criteria is applied for the derivation of vulnerability curves for the serviceability and ultimate limit states, the reliability of SFRC using the proposed practical linear limit state model is evaluated by using the AFOSM(Advanced First Order Second Moment) method and MCS(monte-Calrosimulation) method.

• 대한기계학회논문집
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• 제14권2호
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• pp.358-366
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• 1990

As a basic study to clarify the scoring resistance in lubricated sliding contact, the temperature rise on frictional surface was analyzed by theoretical method and the effects of various factors on the temperature rise were examined. On the basic of the results obtained theoretically, the practical equations to calculate the maximum average temperature of the contact surface were proposed which are applicable to sliding contact. Then, the effects of sliding velocity and oil temperature on the seizure behavior, and the relation between seizure and temperature rise were investigated. The following conclusions are deduced : The maximum average temperature rise and the other bulk temperature. The former is affected by the size of heat supply region and the sliding velocity, the latter is affected by heat transfer coefficient. Without regard to the operating condition such as sliding velocity, oil temperature and operating time at each load-step, the maximum average temperature just before seizure is nearly constant except in the region of lower velocity. Consequently, the maximum average temperature of the contact surface in boundary lubrication is a useful criterion to predict the scoring of sliding contact.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1553-1560
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• 2008

The modern logistics has tried not only to convert the conventional packing system into unit load system using pallet but also to enhance the fitness between packing facilities and transport modes. This is based on the goal to reduce total logistics cost using logistics efficiency. Because the packing unit can affect on both loading rate and loading facilities, the basic form of packing unit is very important to the unit load system. In Korea, the standardization of logistics has been centered on pallet, and the basic condition will be continued except of the variety of standardized pallet form. Because of this, to enhance the standardization of pallet, it is necessary to develop new standard size and form of pallet. The object of this study is to develop a new method of collecting the effectiveness of standardized packing module. The new method is based on measure of effectiveness (MOE) which can be developed by expert survey. This study has originality from the fact that the collecting method for effectiveness of pallet standardization has not been developed up to now.

• 조명전기설비학회논문지
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• 제19권8호
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• pp.77-84
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• 2005

수명예측을 하기 위한 기초 자료로 ACSR의 기계적 시험의 일종인 인장시험이 필요하다. 이 인장시험의 결과들이 경년 변화에 대해 어떤 상관관계가 있는가를 파악하여 통계적으로 처리함으로써 수명예측을 해 볼 수 있다. 통계적 처리기법으로는 회귀분석 방법이 일반적이다. 본 연구에서는 ACSR의 인장시험을 건전 전선과 인공화염으로 열화시킨 전선과, 산불 화염 의해 수거된 열화된 전선에 대해 실시하였다. 수명예측의 한계는 캐나다 Ontario Hydro Research의 기준인 정격 인장강도의 20[%] 손실점을 택하였다. 본 연구에 이용된 ACSR의 규격은 ACSR $480[mm^2]$을 대상으로 하여 비선형 회귀분석을 실시하여 예측수명을 제시하였다.

• 한국기후변화학회지
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• 제5권4호
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• pp.291-300
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• 2014

In this study, we investigated the activity data and basic data of the surface of the water within the ship to be operated by lakes and rivers inland. In this study previously, there was no survey activity data of Ferry and Cruise ship in Korea. In order to ensure the basic data and development of measures to reduce efficiently by local governments, these studies should be performed. Therefore, in the present study was survey the activity data such as cruising time and engine load factor and the specifications of the vessels. As a result, by analyzing the cruising pattern according to the area and the purpose of the cruise, to calculate the emissions of greenhouse gases.

• Wind and Structures
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• 제37권2호
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• pp.153-161
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• 2023

Wind speed data from Nepal and adjoining countries have been analyzed to estimate an extreme wind speed climatology for the region. Previously wind speed information for Nepal was adopted from the Indian National Standard and applied to two orographically different regions: above and below 3000 m elevation respectively. Comparisons of the results of this analysis are made with relevant codes and standards. The study confirms that the assigned basic wind speed of 47 m/s for the plains and hills of Nepal (below 3000 m) is appropriate, however, data to substantiate a basic wind speed of 55 m/s above 3000 m is unavailable. Using a composite analysis of 15 geographically similar stations, the study also generated 435 years of annual maxima wind data and fitted them to Type I and Type III extreme value distributions. The results suggest that Type III distribution may better represent the data. The findings are also consistent with predictions made by Holmes and Weller (2002) and to a certain extent those of Sarkar et al. (2014), but lower than the analysis undertaken by Lakshmanan et al. (2009) for northern India. The study also highlights that the use of a load factor of 1.5 on wind load implies lower strength design MRI's of around 260 years compared to the 700 years of ASCE 7-22.

• 한국지반공학회논문집
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• 제36권11호
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• pp.157-165
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• 2020

현재 국내외에서는 진동기계기초에 진동으로 발생하는 추가 연직 동하중을 산정하고 설계함에 있어서 명확하게 제시된 기준이나 이론이 정립되어 있지 않아 국내의 경우, 심각한 진동조건이 아님에도 불구하고 진동에 의한 추가 동하중을 정적하중의 최대 100%로 간주하는 극히 보수적인 설계가 이루어지고 있다. 본 연구의 목적은 연직 기계진동으로 인하여 정하중외에 추가적으로 발생하는 동적하중의 정량적 크기를 평가하기 위한 모형실험 방안을 제시하는 것이다. 실내 모형실험의 기초실험으로, 제한된 크기의 모형 토조 내에서 발생할 수 있는 진동 반사파의 영향을 분석 및 보완하였고, 제작한 모형 진동기계기초의 고유진동수를 산정하여 실험 시 공진영향을 최소화하였다. 제안된 기법을 적용한 본 모형실험을 수행하여, 중간 조밀도의 모래 기초지반에 놓인 기계진동 얕은 기초에 기계진동에 의해 발생하는 추가적인 동하중의 정량적 크기를 평가해 보았다. 모형실험결과로부터, 현재 국내외에서 제시하고 있는 설계기법의 적합성을 논의해 보았다.

• 한국압력기기공학회 논문집
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• 제12권2호
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• pp.58-65
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• 2016

Since, in case of high energy piping, steam jets ejected from the rupture zone may cause damage to nearby structure, it is necessary to design it into consideration of nuclear power plant design. For the existing nuclear power plants, the ANSI / ANS 58.2 technical standard for high-energy pipe rupture was used. However, the US Nuclear Regulatory Commission (USNRC) and academia recently have pointed out the non-conservativeness of existing high energy pipe fracture evaluation methods. Therefore, it is necessary to develop a highly reliable evaluation methodology to evaluate the behavior of steam jet ejected during high energy pipe rupture and the effect of steam jet on peripheral devices and structures. In this study, we develop a method for analyzing the impact load of a jet by high energy pipe rupture, and plan to carry out an experiment to verify the evaluation methodology. In this paper, the basic data required for the design of the jet impact load experiment equipment under construction, 1) the load change according to the jet distance, 2) the load change according to the jet collision angle, 3) the load variation according to structure diameter, and 4) the load variation depending on the jet impact position, are numerically obtained using the developed steam jet analysis technique.