• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.74-77
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• 1988

This paper reports the properties of antireflection structure and hole formation of Te-based systems. The optical-recording characteristics of metallic recording media are enhanced significantly by incorporating the metal(Al) layer into an antreflection trilayer structure. Due to the interface condition inherent in the design of the trilayer structure, reflectivity from holes is ranked low fraction (<10%). The hole formation is carried by $Ar^+$ Laser(488nm). For 20nsec pulse duration, hole opening power(threschold) of $(Te_{86}Se_{14})_{50}Bi_{50}$ trilayer is lower than that of monolayer that used in this experiment. Hole shapes of the whole sample were clean.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1995년도 특별강연 및 춘계학술발표 개요집
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• pp.74-76
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• 1995

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.823-826
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• 2000

Burr formed in drilling are classified into three types. no burr, burrs with cap, teared burr. To control burr size in drilling. the second type burrs with cap are to be formed because it is small and uniform. It is necessary to understand the mechanism of cap formation to derive the burr formation into second type burr with cap. In several materials, second type burrs are formed in drilling by changing cutting conditions. It is observed that cap is formed as a result of the plastic deformation along the outside of exit hole. According to the tension behavior of the material in concentrated region between hole and drill outside edge, the geometry of burr with cap is determined.

• 한국정밀공학회지
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• 제22권4호
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• pp.52-59
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• 2005

When a micro hole is machined by EDM with a cylindrical electrode, the hole diameter is different at the inlet and the outlet of the micro hole. The taper shape of the micro hole is caused by not only wear of the electrode but the eroded particles. The eroded particles cause secondary discharge during machining the micro hole. As a result, the diameter of the inlet becomes larger than that of the outlet. In this paper, a new method is proposed to reduce the difference in diameter between the inlet and the outlet of the hole. Observed was that the feed depth and machining time affect the formation of taper shape On this experimental basis, ultrasonic vibration was applied to reduce machining time, and capacitance was changed during machining to use the difference in discharging energy of different capacitances. Using the proposed method, a straight micro-hole was fabricated.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.1-8
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• 2004

Applications of the deep hole drilling process can be found in many industries ranging from large aerospace manufacturer to small tool and die shop. Deep hole drilling process with small diameter generally requires high quality and accuracy. But problems which may arise or result from the deep hole drilling process include drill breakage, the generation of a finished part surface which does not satisfy required quality, and process instability. To guaranty the required machining quality and accuracy, it is important to understand and improve the deep hole drilling process. In this study, deep hole drilling experiments using tingle edge drill with small diameter under 2mm have been carried out for difficult to cut materials such as C42CrMo4 and C45pb and the experimental results were analyzed. Feed force and torque versus feed showed linear relationship in both materials. The feed force and torque are decreased as cutting speed is increased but the trends are not uniform in C42CrMo4.

• 한국생산제조학회지
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• 제6권4호
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• pp.138-146
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• 1997

The optimal drill helix angle, point angle, and cutting conditions are recommended in the study so as to maximize the drilling performance by investigating the experimental reaults concerning with the state of chip formation, roundness of machined holes, and geometry of projected burr at hole exit, which are examined under the conditions of various helix angles, drill point angles of twist drill, cutting speeds, and feeds in operional parameters. In the easiness of chip escape, the helical type of chip is producted when a helix angle is 30$^{\circ}$, drill point angle 118$^{\circ}$, 140$^{\circ}$and feed is st between 0.1 and 0.15mm/rev. Roundness of machined hole is improved when the helix angle is 37$^{\circ}$, drill point angle is 118$^{\circ}$, and feed is 0.15mm/rev. The height of projected burr at the button of machined hole increases when the drill point angle and helix angle becomes large.

• 조명전기설비학회논문지
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• 제24권12호
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• pp.57-63
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• 2010

The efficiency of LED package is increasing by applying the high power, and a existing lighting is changing as the LED lighting. However, many problems have appeared by heat. Therefore, in order to solve thermal problems, LED lighting is designing in several ways, but the advantages of LED lighting is fading due to increase the prices and volumes. In this study, we try to improve the thermal performance by formation of via holes. The junction temperature and thermal resistance in the FR4-PCB with via-holes of 0.6[mm] was excellent in experiment and FR4-PCB with Via-holes of 0.6[mm] was excellent in simulation without solder. Further, the thermal resistance and the optical properties can be improved through a formation of via-holes.

• 한국전기전자재료학회논문지
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• 제17권2호
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• pp.228-235
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• 2004

In this thesis, it is designed efficient electrode formation on the organic luminescent device. ITO electrode is treated with $O_2$plasma. In order to inject hole efficiently, there is proposed the shape of anode that inserted plasma polymerized films as buffer layer between anode and organic layer using thiophene monomer. It is realized efficiently electron injection to aluminum due to introduce the quantum well in cathode. In the case of device inserted the buffer layer by using the plasma poiymerization after $O_2$plasma processing for ITO transparent electrode, since it forms the stable interface and reduce the moving speed of hole, the recombination of hole and electronic ate made in the omitting layer. Compared with the devices without buffer layer, the turn-on voltage was lowered by 1.0(V) doc to the introduction of buffer layer Since the quantum well structure is formed in front of cathode to optimize the tunneling effect, there is improved the power efficiency more than two times.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.49-52
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• 2000

The hole flanging experiments are performed on a flat circular plates with a hole in the center and the flangeability and fracture behavior of TRIP steel and ferrite-bainite duplex steel were examined. Over the ranges of conditions investigated, the flangeability of ferrite-bainite duplex steel is better than TRIP steel and the term 'hole flanging capacity' introduced in this study. Fracture behavior of TRIP steel and ferrite-bainite duplex steel was characterized by petal formation at the edge of flange. In case of crack propagation, crack tip diversion that is supposed to be responsible for flangeability occurs more severely on HSLA Steel.

• 소성∙가공
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• 제10권6호
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• pp.465-470
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• 2001

Hole flanging experiments are performed on flat circular plates with a hole in the center and the flangeability and fracture behaviors of TRIP steels and ferrite-Bainite duplex steels were examined. In the hole flanging, deformation by lip and petalling occurs when plates are struck by punches of various shapes and high circumferential strains induced in the target material cause radial cracking and the subsequent rotation of the affected plate material in a number of symmetric petals. In all cases, failure of the plate was due to lip fracture that results from multiple localized neckings that take place around the hole periphery where straining is most severe and a somewhat regular pattern was observed in a fracture shape. The neck characteristics in flange formation and the transition from the lip to petal mode at which fracture occurs were compared with two materials.