• 대한산업공학회지
• /
• 제20권2호
• /
• pp.39-50
• /
• 1994

Most research results on the throughput of unit-load automated storage retrieval (AS/R) systems assume the randomized storage; that is, all slots In the entire rack are equally likely to be selected for the storage location. However, for the most existing AS/R systems which use Closest Open location storage policy, Park[6] mathematically showed that this assumption results in a significant difference from the actual performance of AS/R systems. In this study, we present more details about the performance of the unit-load AS/R systems by considering the rack utilization and rack density; and examine their impact on the throughput of AS/R systems by using computer simulation. A new storage policy named Shortest Cycle Location(SCL) is proposed. Simulation results indicate that the performance of SCL policy consistently outperforms the Closest Open location storage policy. We also define the "Extra-Cost Zone" compared to the "No-Cost Zone"[3] and explore its geometric and practical meaning.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권2호
• /
• pp.306-314
• /
• 2008

General metal welding occurs distortion. Also, reducing distortion is required much cost. Therefore, the purpose of this study is optimization of welding conditions to reduce distortion in welding of monolithic rack housing for modular steering gear. Firstly, heat source for welding was chosen arc and laser. Secondly, it investigated optimizing welding conditions in bead welding by arc and laser heat source, and welding conditions in fillet welding was optimized with welding shapes. Finally, it was measured temperature distribution of welds by infrared camera and angle distortion in fillet welding. As a result, laser welding was superior to arc welding on distortion.

• 대한산업공학회지
• /
• 제30권4호
• /
• pp.306-316
• /
• 2004

We present a closed form approximate analytical model to estimate the expected waiting times for the storage and retrieval requests of an automated storage/retrieval (AS/R) system, assuming that the storage/retrieval (S/R) machine idles either at the rack or at the input/output point. The expected waiting times (and the associated mean queue lengths) can play an important role to decide whether the performance of a stable AS/R system is actually acceptable, to determine buffer size (or length) of the input conveyor, and to compute the number of the rack openings which is required to hold the loads which are requested by processing machines but waiting in the rack to be retrieved by the SIR machine. This model can be effectively used in the early design stage of an AS/R system.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.1760-1764
• /
• 2003

This study was carried out to establish an analytical method on the open circuit seawater pipeline network for open rack vaporizers(ORVs). The linear theory method was chosen to solve this network system. In particular, the method was modified to calculate the static pressure at each node and to determine the operating condition of each pump with the mean static pressure of pumps and ORVs. The proposed method is the first report demonstrating that can be used as a solver for the complicated open circuit. Also, the method indicated the importance for exactly calculating equivalent length of pipes including valves, bends, fittings, and others to raise the accuracy. Although this technique is good for solving this system, it is still required to improve the convergence rate.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2005년도 춘계 학술대회논문집
• /
• pp.41-46
• /
• 2005

A new PC cluster was designed and constructed based on Windows XP Operating system. Primary target of the present design was the high node density per rack by using the general PC parts those are cost-effective and readily available in the market. Other major design points were system cooling and the convenient maintenance using standard PC parts. Presently 24 nodes per rack seems to be optimum considering the specification of the network switching device, system cooling and power supply, but 40 nodes can be accommodated within a single rack at maximum. Windows XP was selected as a high-performance computing environment considering the cost and the convenience in acquisition, maintenance and education. Both fast-Ethernet and Gigabit Ethernet network connection were tested and compared with previous data, especially for Linux doter using Myrinet. The result shows that there is no significant difference between the operating systems and the Fast-Ethernet and/or Gigabit Ethernet are good solution for the high-performance PC cluster considering the cost and performance.

• 대한기계학회논문집A
• /
• 제27권8호
• /
• pp.1317-1323
• /
• 2003

In this paper, In-air and in-water vibration characteristics of Rotary Specimen Rack(RSR) are estimated through 3D finite element analysis by using ANSYS software. Added mass is calculated by using Blevins' equation. To confirm the accuracy of the results presented in this study, obtained results are compared to those of using a theoretical equation. It is confirmed that in-water natural frequencies of the RSR are lower than in-air ones due to tile added mass effect of the fluid. Also, good agreement is founded between natural frequency ratios obtained by a theoretical equation and those of using ANSYS.

• 동력기계공학회지
• /
• 제14권3호
• /
• pp.64-70
• /
• 2010

In this study, designing of precise linear transferring device which can be applied to industrial machine and robot industry has been introduced. The direction of power flow and output feature are similar to current Rack-Pinion type. However, unlimited length extensity via rack modulizing, and securing high velocity transportation have been realized by applying Pin-Pinion Gear type at the operation part. The analysis has been calculated to obtain the Pin-Pinion Gear's optimized tooth profile. As a result of research, it is impossible to control precisely even overlap at the teeth of involute and sprocket. Because they have peculiar gearing structure. Therefore, modified cycloid tooth has been proposed to perform high velocity, precise control without backlash.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2015년도 제52차 하계학술대회논문집 23권2호
• /
• pp.183-184
• /
• 2015

본 논문에서는 데이터 센터 내 전력 효율화에 기여할 수 있는 랙 단위 공조방식에 대하여 제안한다. 스마트 폰과 태블릿 등 모바일 디바이스의 확산으로 디지털 콘텐츠와 데이터가 폭발적으로 증가하면서 데이터 센터의 수는 연평균 30%이상 증가하고 있다. 따라서 데이터 센터 내 냉방장비 영역의 효율성을 증가시킬 필요성이 대두되고 있다. 본 연구는 데이터 센터의 냉각비용을 증가시키는 전력 사용량을 줄이고자 진행되었으며 3종류의 냉각 아키텍처 방식 중 랙 단위 아키텍처가 불필요한 냉각 전력 소비를 줄인다는 것을 확인하였다.

• 조명전기설비학회논문지
• /
• 제22권5호
• /
• pp.108-115
• /
• 2008

최근, 디지털 디머 시스템의 수요는 꾸준히 증가하고 있는 추세이다. 하지만, 국내 연구는 그에 비하여 미비한 실정이다. 본 논문에서는 디지털 디머 장치들을 설계, 제작하고, 시스템을 구성하는 방법을 제안한다. 디지털 디머 장치들은 크게 콘솔과 디머 랙으로 나눌 수 있으며, 콘솔은 GUI환경의 사용자 인터페이스를 제공하여 손쉽게 각 조명기기를 제어하는 패턴을 구현하며, 디머 랙은 콘솔로부터 전송받은 각 조명 레벨을 위상각 제어 방식으로 조명기기의 밝기를 제어한다.

• 한국산학기술학회논문지
• /
• 제17권6호
• /
• pp.199-206
• /
• 2016

본 연구는 다양한 세균에 오염된 신발을 효과적으로 살균하고 탈취할 수 있는 신발장을 설계하기 위한 최적의 조건을 확립하고자하는 목적으로 실시하였다. 신발장의 제작과 평가는 2014년 10월부터 2015년 9월까지 1년에 걸쳐 진행하였다. 항균성능의 평가는 JIS Z 2801:2010 규격에 따라 대장균과 황색포도상구균 균주에 대하여 실시하였고, 탈취효율은 한국공기청정협회 실내공기청정기 규격인 SPS-KACA002-132:2006 규격에 따라 실시하였다. 대장균과 황색포도상구균 균주에 대한 UV 조사시간에 대한 항균성능을 시험한 결과에서 30초 후에 99.9% 이상의 세균감소율을 보였고, 시험가스에 대한 평균 탈취효율은 42.5%를 보였다. UV램프로 5분의 점등과 25분의 소등을 반복하여 작동을 할 경우에 신발 내부와 신발장 내부 온도는 약 $40^{\circ}C$ 와 $25^{\circ}C$ 이하로 유지되었다. 신발장의 작동시간에 따른 온도 변화를 측정한 결과는 UV램프를 점등과 소등을 반복적으로 작동시켜 신발 내부의 온도를 적절하게 유지할 수 있었다. 결과적으로 실제 신발장 내부의 용적은 시험연구원의 챔버 용적보다 매우 작은 용적을 가지고 있기 때문에 시험결과의 값을 상대적으로 보정하게 되면 실제 탈취효율은 측정값보다 매우 클 것으로 판단이 된다. 또한 신발의 내부에서 악취를 유발하는 원인균인 박테리아를 반복적으로 살균하기 때문에 신발 내의 실제 탈취의 효과는 더욱 증가될 것이다. 추가 연구로 일정한 신발장 내부의 온도편차를 찾아야 할 것이다.