• 한국전기전자재료학회논문지
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• 제36권4호
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• pp.369-375
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• 2023

In this paper, we compared and analyzed the power load patterns of dormitory buildings and office buildings to use them as basic data (demand analysis and capacity design) for the design and operation of microgrids for multi-use facilities, and the following conclusions were got. During the daytime on regular weekdays, the power consumption load pattern of office buildings was relatively large at 264.0~332.3 kWh, and during the evening hours, the power consumption load pattern of dormitory buildings was relatively large at 233.0~258.3 kWh. In the case of vacation, during the daytime on weekdays, the power consumption load pattern of office buildings was relatively large at 279.1~407.4 kWh, and in the evening, the power consumption load pattern of dormitory buildings was relatively high at 280.1~394.1 kWh. During the daytime on regular weekends, the power consumption of dormitory-type buildings was relatively high at 133.5~201.6 kWh, and it was found that the power consumption of dormitory-type buildings appeared relatively high at 187.5~252.1 kWh. During a vacation in the daytime on weekends, the power consumption of dormitory-type buildings was found to be 186.5 kWh~ and 218.6 kWh. The increase in power consumption during a vacation (December-February) compared to normal (April-June) was thought to be due to an increase in electricity demand, and the reason for the higher power consumption in dormitory buildings during the vacation was due to reduced working hours in office buildings.

• 한국항공우주학회지
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• 제49권3호
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• pp.205-212
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• 2021

본 연구에서는 플렉셔를 적용한 추력 시험대 설계를 위해 두 가지 유형에 따른 추력 시험대 모델링을 제시하였다. Type A의 모델은 접선 하중(추력)과 지면에 대한 축 방향 하중(자중)이 압축하중으로 발생되고, Type B의 모델은 축 방향 하중이 인장하중으로 발생되도록 설계를 하였다. 두 가지 유형에 대해 하중에 따른 영향성을 확인하였고, 1D 계산 결과와 전산해석 결과에 대해 비교를 수행하였다. 거리 비(x/L)에 대해 총 10구간을 1D 계산 값과 전산해석 값을 비교하였고 그 결과는 매우 유사한 것을 확인할 수 있었다. 해석 결과에 대한 타당성을 입증하기 위해 플렉셔에 대한 전산해석으로부터 등가응력(Equivalent Stress)을 확인하였고, 항복조건(Von-Mises Yield Criterion) 평가로부터 Type B 모델의 제작을 선정하였다.

• Tribology and Lubricants
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• 제37권4호
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• pp.136-143
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• 2021

This paper presents the loosening behavior that occurs after the application of an external load to internal and external connection types of dental implants using the finite element method. We use fastening force between an abutment and a fixture to clamp the dental implant system; however, loosening and breakage may occur owing to cyclic external loads. In this study, we considered the initial fastening condition in the pre-load analysis and then investigated the change in stress and contact surface status when applying external loads. After the application of the initial fastening load, we verified that the internal connection-type model exhibited a relatively lower stress distribution than that of the external connection-type one. Moreover, we found that the former model showed a lower stress concentration after the application of the external load. In addition, after the application of this load, we found that the higher the shear load acting on the implant system, the higher the possibility of loosening. The study results showed the change in stress distribution and contact surface according to the connection type of the dental implants and the phenomenon of loosening by cyclic loads. We expect that the results of this study will be useful for the study of reliability and design of dental implant systems.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.643-649
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• 2008

The purpose of this study is to establish a standard for unit cooling load in central control type apartment applied district cooling. The model of unit household was selected. And the standard of coefficient of overall heat transmission, location of unit household, indoor air temperature, solar radiation & thermal conduction at window and interior load was selected, and region, expansion or non-expansion of balcony, pyeong type, azimuth, rate of window area was applied as parameter. And then cooling load simulation was performed. Based on the result of simulation, the synthetic district cooling load was presented for selecting heat source of apartment applied district cooling, and unit cooling load was analyzed according to design parameter.

• 대한치과교정학회지
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• 제21권3호
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• pp.543-560
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• 1991

Practitioners are aware of the presence of friction between bracket system and archwire during sliding movement of teeth. Clinically a mesiodistally applied force must exceed the frictional force to produce a tooth movement. The objective of this study were to determine, on a dry condition, changes in magnitude of friction with respect to load, 3rd order inclination (Torque), archwire materials and ligature type. Three wire alloys (Stainless Steel, TMA, NiTi) in two wire sizes (.016, .016x, .022 inch) were examined respect to two bracket system (Straight, Standard), and two ligature type (Metal, Plastic ligature) at three levels of load (100g, 150g, 200g). The results were as follows; 1. Frictional resistance was found to increase with increasing load for S.S., TMA, NiTi. 2. The straight bracket system was exhibited more frictional force than standard bracket system for .016x, .022 S.S. tightly ligated metal ligature. But, torque difference did not increase friction for loose metal ligature & plastic ligature. 3. Regardless of the ligature type, torque and load, stainless steel wire sliding against stainless steel exhibited the lowest friction, and TMA sliding against stainless steel exhibited the highest friction. 4. The loose stainless steel ligature generated lower frictional resistance than plastic ligature in all experimental groups. 5. The following factors affected friction in decreasing order; wire material ligature type, and load.

• 대한기계학회논문집A
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• 제37권5호
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• pp.685-691
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• 2013

로드셀형 풍향풍속계는 바람의 벡터적 성질을 이용한다. 본 연구를 통해 개발된 풍향풍속계는 기존과 달리 풍속계의 날개부가 회전하지 않는 고정형이다. 로드셀형 풍향풍속계를 개발하기 위해서는 측정된 4개 날개의 압력비와 풍향, 압력합과 풍속사이의 관계식을 각각 도출해야 한다. 본 연구에서는 압력비와 풍향사이의 관계식을 도출하기 위하여 각각 ANSYS CFX를 이용한 해석적 접근과 풍동실험을 이용한 실험적 접근을 적용하였다. 해석시 $0^{\circ}$에서 $90^{\circ}$까지 $7.5^{\circ}$ 간격으로 풍향조건을, 실험시 $10^{\circ}$ 간격으로 10가지 풍향조건을 설정하였다. 또한 실험 및 해석적 접근을 통해 압력비와 풍향사이의 관계식을 도출하였다.

• 한국도로학회논문집
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• 제8권3호
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• pp.29-37
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• 2006

본 연구는 현재 수행중인 "한국형 포장 설계법 개발과 포장성능 개선방안 연구"의 일환으로 역학-경험적 포장 설계법에 사용될 교통하중 입력변수를 정량화하기 위해서 실시하였다. 교통하중 정량화를 위하여 기존의 ESAL 개념이 아닌 축하중 스펙트럼을 이용하였다. 이를 위하여 교통량 통계 연보내 교통량 자료를 가지고 일반 국도에 대한 대표 축하중 조사지점을 차로별, 지역특성별 구분에 따라 33개 지점을 통계적 방법을 이용하여 선정하였다. 그리고 선정된 대표 지점을 대상으로 축하중 계측기를 이용하여 각 차종에 대한 축하중을 조사하였다. 측정된 축하중 자료는 각각 분류된 조건에 따라서 축하중 스펙트럼으로 표준화하였으며, 그 방법으로 누적밀도함수인 S-커브 곡선을 이용하여 각 조건별 계수를 제시하였다.

• 한국지반공학회논문집
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• 제21권5호
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• pp.51-58
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• 2005

본 연구에서는 말뚝지지 전면기초에 대한 대규모 모형실험을 실시하여 여러 가지 조건에 따른 하중분담률을 측정하였다. 모형실험은 동일한 조건하에서 비접촉 무리말뚝과 말뚝지지 전면기초 두가지 상태로 실시되었고, 지반의 상대밀도와 종류, 말뚝길이, 간격, 배열상태와 말뚝관입방법 등의 조건들을 변화시켜 실험을 실시하였다. 모형실험 결과, 말뚝관입방법과 지반 종류에 따른 하중-침하 곡선은 큰 차이가 없는 것으로 나타났다 재하하중이 작은 경우에는 대부분의 하중을 말뚝들이 부담하지만, 하중이 커지면 래프트도 상당한 하중을 분담하는 것으로 나타났다. 모래지반의 상대밀도가 높을수록 말뚝지지 전면기초의 하중분담률은 감소하는 경향을 나타내며, 말뚝간격이 넓어지고, 말뚝길이가 길어질수록 하중분담률은 증가하는 경향을 나타냈다. 그러나 말뚝관입방법과 하부 지반의 종류는 말뚝지지 전면기초의 하중분담률에 큰 영향을 주지 않는 것으로 평가되었다.

• Journal of Mechanical Science and Technology
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• 제16권6호
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• pp.776-784
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• 2002

We have performed experimental studies for the improvements of pneumatic brake systems of freight trains. Currently, most of the freight trains operated by the Korean National Railroad have either empty-load or diaphragm type brake systems. In this study, appropriate methods that the air pressure characteristics in both type of brake systems are in accordance with each other have been investigated. We have also performed running tests using a 30 car-train set to design optimum capacity of a quick release valve. The test results show that the quick release valve is considerably effective in shortening the release time of the diaphragm type brake system. In the case of a normal brake application, the diaphragm type brake system with the quick release valve reduces the release time to 34% of that of the system without the quick release valve. This release time is almost equivalent to that of the empty-load type brake system. Accordance of braking performance in different types of brake systems in a train set is expected to prevent wheel flats and to reduce maintenance costs.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1-6
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• 2003

In this paper, we design a wedge type rail clamp which can protect container crane from wind with constant clamping force regardless of the operating period. When we design wedge type rail clamp. it is important to determine the angle of wedge and analyze a contact condition of roller and wedge so that we might develop a rail clamp with variable capacity. Therefore, this paper suggest a process to decide wedge angles within feasible range which could be obtained using load analysis and FEA of wedge type rail clamp.