• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.587-590
• /
• 2000

The new core making method economized on core sand requested. The new method is heating core box until it reaches reasonable temperature and then spraying core sand with core binder into core box. Inner temperature distribution have to uniform in order to form core of uniform thickness. Therefore, in this study we treat of inner temperature distribution of core box in priority. First, determine proper torch number. Next, optimize the torch position to minimize the average of absolute deviation(AVEDEV) of inner temperature. The results are as followed : 1. The torch number that makes inner temperature distribution about $300^\circ{C}$ uniformly is 25. 2. When $S_H$ and $S_V$ is 0.7, the torch position is optimized and AVEDEV is 5.85.

• 한국정밀공학회지
• /
• 제19권1호
• /
• pp.43-47
• /
• 2002

The new core making method economizing the amount of core sand has been requested. The new method is that a core box is heated until it reaches reasonable temperature and then core sand with core binder is sprayed into the core box. Since inner temperature distribution have to be uniform in order to form uniform thickness of core, we studied inner temperature distribution of core box. First, we determined proper number of torches and optimized torch positions to minimize the average of absolute deviation(AVEDEV) of inner temperature. The results are as fellowed: 1. The number of torches that enables uniform inner temperature distribution about $300^{\circ}C$ is 25. 2. When $S_H$ and $S_V$ is 0.7, the torch positions are optimized and AVEDEV is 5.85.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.938-941
• /
• 2011

이 논문은 에그-박스 코어의 등간 전단 탄성계수에 대해 다루고 있다. 코어의 등가 전단 탄성계수를 얻는 방법으로 유한요소해석, 수치 해석, 실험이 있다. 이번 연구에서는 에그-박스 코어의 등가 전단 탄성계수를 평가하기 위하여 3점 굽힘 시험을 수행하였으며, 그 결과로부터 상온에서의 에그-박스 코어의 등가 전단 탄성계수를 획득하였다. 이 결과를 유한요소해석으로부터 얻어진 결과와 비교하였다.

• 한국추진공학회지
• /
• 제18권2호
• /
• pp.73-79
• /
• 2014

본 논문에서 다루고 있는 에그-박스 코어는 공기 흡입식 추진기관의 연소실 케이스로 사용되고 있다. 무게의 경량화 및 제작 비용/시간을 절감하기 위한 목적으로 에그-박스 코어의 피치 길이 및 두께 변경의 필요성이 대두되었다. 짧은 시간 내에 에그-박스 코어 변경에 있어 연소실 케이스의 구조 안정성에 영향을 미치는 등가 전단 탄성계수의 특성을 파악할 수 있는 방법으로 굽힘 시험을 모사한 유한요소해석을 이용하였다. 등방성 재료인 H130-폼 코어를 가지는 샌드위치 판넬에 대한 유한요소해석을 수행하여 얻은 전단 탄성계수 값이 참고문헌에서 주어진 값과 거의 일치함을 확인하였다. 에그-박스 코어의 피치 길이와 두께 변화에 따른 등가 전단 탄성계수 변화를 확인할 수 있었다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
• /
• pp.123-126
• /
• 2011

에그-박스 코어의 등가 전단 탄성계수를 예측하기 위하여 유한 요소 해석을 수행하였다. 유한 요소 해석을 통한 등가 전단 탄성계수 예측 방법을 검증하기 위하여 등방성 재료인 H130-폼 코어에 대한 유한 요소 해석을 수행하였다. 유한 요소 해석을 통해 얻어진 전단 탄성계수와 참고 문헌에서 주어진 전단 탄성계수가 일치함을 확인하였다. 에그-박스 코어의 상온 및 고온에서의 등가 전단 탄성계수 변화를 확인할 수 있었다.

• International Journal of Aeronautical and Space Sciences
• /
• 제4권2호
• /
• pp.17-25
• /
• 2003

Simple methods are developed to predict temperatures of a satellite box during launch stage. The box is mounted on outer surface of satellite and directly exposed to space thermal environment for the time period from fairing jettison to separation. These simple methods are to solve a 1st order ordinary differential equation (ODE) which is simplified from the governing equation after applying several assumptions. The existence of analytical solution for the 1st order ODE is determined depending on treatment of time-dependent molecular heating term. Even for the case that the analytical solution is not available due to the time dependent term, the 1st order ODE can be solved by relatively simple numerical techniques. The temperature difference between two different approaches (analytical and numerical solutions) is relatively small (Jess than $1^{\circ}C$ along the time line) when they are applied to STSAT-I launch scenario. The present methods can be generally used as tools to quickly check whether a satellite box is safe against space environment during the launch stage for the case that the detailed thermal analysis is not available.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.406-408
• /
• 1996

This paper describes the BLDC motor which is applicated for a top front loading domestic washing machine. This motor is adopted direct drive washing machine without gear-belt-pulley system. Because gear box is removed, machine volume and noise are reduced. Moreover mechanical troubles in gear box are removed. Realization of variable speed region through of PWM control and high speed is able to efficient washing and spinning.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
• /
• pp.311-314
• /
• 2005

This research aims to analyze of prestressed composite hollow-core slab and box type steel beam. The smeared crack model used in abaqus for the modeling of hollow core reinforced concrete, including cracking of the concrete, rebar and concrete interaction using the tension stiffening concept, and rebar yield. The structure modeled is a simply supported hollow core spancrete slab subjected spa-h beams and prestressed in one direction. The hollow core spancrete slab is subjected to four-point bending. The concrete-rebar interaction that occur as the concrete begins to crack are of major importance in determining the spancrete slab's response between its initial, deformation and its collapse. This smeared crack model used in analysis involved non-liner concrete analysis concept.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제10권3호
• /
• pp.403-412
• /
• 2018

Medium-scale tests were conducted to measure and observe the strength and failure behavior of freshwater ice rubble. A custom box measuring $3.05m{\times}0.94m{\times}0.94m$, with Plexiglas walls was built so that failure mechanisms could be observed. Ice rubble beams of nominal thickness 50 cm were produced by placing randomly sized ice pieces into the box filled with water at its freezing temperature. After the specified consolidation time, ranging between 0.2 and 70.5 h, the ice rubble beam was deformed by pushing a platen vertically downwards though the center of the beam until failure. For consolidation times less than 4 h, the ice beam failed progressively and tended to fail by shearing on macroscopic scale. At times greater than 4 h the beam failed by bending. The change in failure behaviour has been attributed to the degree of bonding between ice blocks.

• Advances in Computational Design
• /
• 제5권1호
• /
• pp.35-54
• /
• 2020

One of the prevailing structural systems in high-rise buildings is the core-wall system. On the other hand, the existence of one or more underground stories causes the perimeter below-grade walls with the diaphragm of grade level to constitute of a very stiff box. In this case or a similar situation, during the lateral response of a tall building, underground perimeter walls and diaphragms that provide an increased lateral resistance relative to the core wall may introduce a prying action in the core that is called backstay effect. In this case, a rather great force is generated at the diaphragm of the grade-level, acting in a reverse direction to the lateral force on the core-wall system, and thus typically causes a reverse internal shear. In this research, in addition to review of the results of the preceding studies, an improved relationship is proposed for prediction of backstay force. The new proposed relationship takes into account the effect of foundation flexibility and is presented in a non-dimensional form. Furthermore, a specific range of the backstay force to lateral load ratio has been determined. And finally, it is shown that although all suggested formulas are valid in the elastic domain, yet with some changes in the initial considerations, they can be applied to some certain non-linear problems as well.