• 마이크로전자및패키징학회지
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• 제19권4호
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• pp.39-43
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• 2012

Via-filling plating and through-hole plating are absolutely imperative for manufacturing of printed-wiring board. This Paper is introducing the latest developments of our company worked on the high-performance of acid copper plating additives for them.

• 한국해양공학회지
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• 제1권2호
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• pp.74-82
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• 1987

This study has been made to investigate into the behavior of fatigue limit, of fatigue crack initiation, and of fatigue crack propagation under the condition of rotating bending stress; specifically on the independency of stress field as well as the crack behavior of surface micro hole defect, which is made artificially through the specimen. The results obtained can be summarized as followa; 1) For the single micro hole defect, initiation of fatigue crack is occurred at both tips of microhole defect simultaneosly along the slip which are produced in the range of maximum principal stress arround micro hole defect independent of the size of micro hole defect. 2) For the neighbored deuble micro hole defects with equal size, in the range ($\frac{L}{r}$)ratio $\gtrsim$ 3 defined as the size of micro hole defect(2r) to the distance between the centers of micro hole defects (2L), the crack behavior of the micro hole defects is same as single one. However, for the range of $\frac{L}{r}$<3, the interference effect becomes significant as the ratio approaches to 1.

• 한국분무공학회지
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• 제25권4호
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• pp.154-161
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• 2020

A single spray plume is the basic unit of the entire spray plume and is an important factor in understanding the spray characteristics. However, since the multi-hole GDI injector has a narrow spray angle, the superposition of the spray plumes occurs severely. Therefore, the spray uniformity and the spray atomization characteristics of a single spray plume were analyzed in this study using a single-hole GDI injector. Five single-hole GDI injectors with different nozzle hole diameters were used in the experiment. The uniformity of the spray was evaluated through the analysis of the spray pattern images. In addition, the atomization characteristics were compared using the diameter distribution of the spray droplets obtained using PDPA. As a result, the larger diameter of the nozzle hole, the less uniformity of the spray, and the injection pressure did not have a significant effect on the spray uniformity. It is judged that the surface roughness of the injector has a greater effect on spray uniformity than the diameter of the nozzle hole. Also, the size of the spray droplets increased sharply when the diameter of the nozzle hole was 230 ㎛.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.101-106
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• 2001

This paper presents experimental results for the confining characteristics of cylinder with center-hole and spiral reinforcements. The experiments have been conducted for the specimens with primary variables i.e., spiral reinforcement ratio and diameter of center-hole which affect the compressive strength and stress-strain relationship. Through this research, it was found that the compressive strength and ductility were increased with the ratio of spiral reinforcement because the lateral expansion of the concrete inside the spiral was restrained by the spiral, but dependent on the size of center-hole.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.208-211
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• 2001

In the drawing from round billet to non-circular section there are two different processes through solid hole die(HD) and the other cassette roller dies(CRD). The CRD process has several cassette type rollers and a billet is able to move through the given gaps between two profiled rollers. The objective of this study is based on the analysis and evaluation of two aforementioned processes using experiments and finite element simulation. In order to simulate the multi-stage drawing process from circular sectioned billet to rounded square section, the finite element analysis is applied to the process using a commercially available DEFORM-3D code. Two types of experimental drawing tests through designed and manufactured dies for pure copper and aluminum alloy are carried out at room temperature. The analysis included comparison of material properties before and after drawing of each process and also provide some useful information by a FEM simulation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.237-240
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• 2003

Deformation surrounding the hole in the tube during the hydro-piercing process has been investigated in this study. The tube is expanded and internally pressurized between upper and lower dies, and a piercing punch is driven forcefully through a cross passage in the die and through the wall of the tube. The pressurized fluid within the tube provides support to the wall of the tube during a piercing step to form a hole in the tube having less deformation surrounding the hole in the tube. The deformation area may be fully retracted to a substantially flat form or partially retracted to a countersunk form. In this study, a mathematical model that can predict deformation surrounding the hole has been proposed and experimentally verified by actual hydro-piercing test.

• 반도체디스플레이기술학회지
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• 제6권1호
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• pp.59-64
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• 2007

Non-contact transportation of a large-sized glass plate using air cushion for the vertical sputtering system of liquid crystal display (LCD) panel was considered. The objective of the study was to design an air pad unit which was composed of multiple injection and exhaust holes and mass flow supplying pipe. The gas was injected through multiple small holes to maintain the force for levitating glass plate. After hitting the plate, the air was vented through exhaust holes. Complex flow field and resulting pressure distribution on the glass surface were numerically studied to design the air injection pad. The exhaust hole size was varied to obtain evenly distributed pressure distribution at fixed diameter of the injection hole. Considering the force for levitating glass plate, the diameter of the exhaust hole of 30 to 40 times of the gas injection hole was recommended.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.261-273
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• 2004

이 연구에서는 경제적이고 실용적인 지반의 동적물성치 계측 기술 개발을 위해 인홀시험법을 연구하였다. 이번 연구에서는 개발한 인홀 장비는 NX 크기의 검측공에서 사용할 수 있고 맨손으로 다룰 수 있을 정도로 작고 가볍다. 그리고 기존의 인홀 장비를 보다 편리하게 개량하였다. 또한, 인홀 시험에 있어서 최적의 댑퍼를 개발하였다. 이 장비는 여러 현장에서 크로스홀 시험과 인홀 시험을 통해 성능을 검증하였다.

• 한국전산유체공학회지
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• 제21권1호
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• pp.64-71
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• 2016

This research is to numerically investigate the convective cooling performance in the Disk brake. Research concentrates on the heat transfer coefficient and cooling performance which are selected with cooling local locations. Cooling performance of the Hole disk has been compared by Ventilated Disk. According to the results of heat transfer on the disk brake, activated velocity distributions more appear in the Hole disk. This is due to the fact that a number of hole units have exactly 120 on the surface of the hole disk. Therefore, velocity distributions of hole disk brake is better activated than Ventilated disk. According to the calculations of Nusselt number between surface and atmosphere in the interested cooling area, average value of cooling effect has been increased 13.5% by the hole disk at driving of speed 65 km/h situation and grown 18% by the hole disk at driving speed of 100 km/h. Due to the flow of air through the hole route, cooling performance of the hole disk was very excellent. In addition, cooling effect on edge of the bottom is better than the vicinity of center.

• 한국환경과학회지
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• 제27권3호
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• pp.155-165
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• 2018

Observations were conducted in Uiseong Binggye-ri Ice Valley of Korea, where a low temperature talus is located. The talus temperature at Ice Hole near the lower end of the talus remained at $0^{\circ}C$ until summer or autumn and averaged $-0.3^{\circ}C$ over 2 years. The talus temperature at Warm Hole was much higher than the external air temperature during autumn and winter. The outflow of warm air at Warm Hole begins in the late summer of fall. The direction of airflow through the talus surface was determined by the relationship between talus temperature and external air temperature. Annual variations in talus temperature and air exchange between the talus and the external environment can be divided into four periods. It was found that the airflow directions at Warm Hole and Ice Hole were not necessarily opposites. The outflows from the talus at Ice Hole and Warm Hole can occur simultaneously.