• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.80-85
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• 2002

The free curve gear is a non-circular gear without any relating center, which can perform free curve motion for complicated mechanisms, and minimize the work area. In this study, an algorithms for tooth profile generation of free curve involute gear is developed. The algorithm uses the involute gear creating principle in which a gear can be generated by rolling with another standard involute one. Cycloid me and third polynomial curve gears were designed and verified by computer graphics. These gears are manufactured in the wire-cut EDM and examined in engagement with a standard spur gear. The results showed that the proposed algorithm is successful to design and to manufacture the free curve gear with concave and convex profiles.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.256-259
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• 2008

An micro-probe tip must be manufactured using thin film to evaluate integrity of the semiconductor with narrow distance between pads. In this study, fatigue tests were performed for BeCu thin film which is used in micro-probe tip of semiconductor test machine. The thin film was manufactured by electro plating process, and the specimens were fabricated by wire-cut electric discharge method to make hour glass type specimen of $5000{\mu}m$ width, $29200{\mu}m$ length and $30{\mu}m$ thickness. The fatigue test of load control with 10Hz frequency was performed, in ambient environment. The fatigue cycles were tension-tension with mean stress, at stress ratio, R=0.1.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.2
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• pp.5-11
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• 2005

Among the micro machining techniques, micro EDM is generally used for machining micro holes, pockets, and micro structures on difficult-cut-materials. Micro EDM parameters such as applied voltage, capacitance, peak current, pulse width, duration time are very important to fabricate the tool electrode and produce the micro structures. Developed micro EDM machine is composed of a 3-axis driving system and RC circuit equipped with pulse generator. In this paper, using micro EDM machine, the characteristics of micro EDM process are investigated and it is applied to micro holes, slots, and pockets machining. Through experiments, relations between machined surface and voltages and between MRR and feedrate are investigated. Also the trends of tool wear are investigated in case of hole and slot machining.

• Journal of Welding and Joining
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• v.33 no.1
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• pp.72-79
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• 2015

Evaluation of fracture toughness of welded structures has a significant influence on the structural design. However the residual stresses is redistributed while the welded structures is cut for preparing specimens. This study investigated an effect of the welding residual stress redistribution on the impact absorption energy of Charpy specimen. SA516Gr70 steel plate by at the flux cored arc welding (FCAW) and gas tungsten arc welding(GTAW) was cutting. Specimens for Charpy impact testing were taken from the welded plate. Two material removal mechanisms (wire cutting and water jet) were used to make the specimens. Welding residual stress and redistribution residual stress were measured using the XRD (X-Ray Diffraction) method. The amount of redistribution of residual stress depends on the different material removal mechanism. Redistribution of residual stress of reduced the impact absorption energy by 15%.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.314-317
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• 2003

높은 정밀도와 고품위 가공이 요구되는 금형제작 등에서 사용되는 고정밀 와이어컷 방전가공기가 고속, 고정밀 가공특성을 갖기 위해서는 무엇보다도 제어와 출력특성이 우수한 고성능의 전원장치가 필요하다. 본 논문에서는 고정밀 와이어컷 방전가공기용 스위칭모드 보조 전원장치로 사용되는 200W 280Vdc 영전압 포워드 컨버터 개발에 대해 기술하고 있다.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1369-1375
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• 2006

This study analyzes stability and the reason of slope failure about cut slope on stony mountain in Acheondong, Guri and suggests the reasonal reinforce method. Based on the results of the subsurface exploration, laboratory tests, and the numerical analysis of finite element method, the potentials of plane and wedge failure are highly estimated. The safety factor was 1.2 under dry and 1.06 wet condition. The most proper reinforce method to raise the safety factor more than 1.5 was the way to control displacement by using step retaining wall, earth anchor, wire mesh, and rock anchor.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1259-1261
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• 2003

고정밀 와이어컷 방전가공기는 높은 정밀도를 갖는 금형제작에 사용되고 있는 공작기계로서 최근 나노단위의 가공기술이 요구되는 산업추세에 발맞추어 고속, 고정밀 가공특성을 갖추도록 전반적인 성능개선이 이루어지고 있다. 본 논문에서는 기존 Thyristor를 이용한 위상제어 방식보다 우수한 특성을 갖는 스위칭모드 방식의 10kW급 직류 전원장치의 개발에 대해 기술하고있다.

• Applied Microscopy
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• v.10 no.1_2
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• pp.7-17
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• 1980

Electron microscope radioautography introduced by Liquier-Milward (1956) is now used routinely in many laboratories. Most of the technical difficulties in specimen preparation have been overcome. This method is modified from loop method for improvement of EM radioautographic techniques. The advantages of this method are: 1. the use of single specimens on small corks and of a large wire loop, allows the experimenter to avoid the blemishes in the membrane; 2. the surfactant dioctyl sodium sulphosuccinate is added to diluted ILford L4, thus greatly prolonging the period of time over which good emulsion layers can be made; 3. corks can be handled in perspex holder which allows about 20 specimens to be developed simultaneously. The steps of the method comprise: 1. Cut ribbons of ultrathin sections of silver interference colour 2. Pick them up on formvar-coated 200 mesh grids 3. Prestaining of tissues 4. Coat the specimens with a thin layer of carbon by evaporation (30-60A) 5. Mount the specimens on corks (about 1cm apical diameter) using double-sided scotch tape 6. Emulsion coating; a. Take a 250m1 beaker, place it on the pan of a sliding weight balance and weigh it. Add 10 grams extra to the beam. Add pieces of ILford L4 emulsion to the beaker until the balance is swinging freely. Add the 20ml of distilled water that was previously measured out. b. Surfactant dioctyl sodium sulphosuccinate is added to diluted ILford L4. 7. Prepare a series of membranes of gelled emulsion with the wire loop and apply one to each cork-borne specimen. 8. Put the specimens away to expose by pushing the corks into short length of PVC tubing, each tube having a small hole in the side 9. Place the tubes in small boxes together with silica gel. 10. Exposure 11. Developer - Kodak Microdol X for 3 minutes 12. Fixer - A perspex holder can be manufactured which allows 20 specimens to be developed simultaneously. 12. Fixer - 30% sodium thiosulfate for 10 minutes 13. Examination with Siemens Elmiskop 1A electron microscope

• The Journal of Korean Academy of Prosthodontics
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• v.22 no.1
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• pp.123-132
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• 1984

To evaluate the microstructure of various combination clasp joint in removable partial denture, the auther selected framework alloys (Type IV gold alloy, Dentaurium, Ticonium 100) and wrought wires (gold alloy, Ticonium) for this study. Twelve series of combination joints were made by investment soldering technic and wrought wire embedded casting technic. All specimens were cut cross-sectionally and longitudinally, then examined with metallurgical microscope. The results were as follows; Some diffusion was observed in the properly constructed combination clasp joints. In soldered joints, empolying precious alloys were more favorable than non-precious alloys. In castion joints, assemblage of same alloy between framework and wrought wire was superior to other groups. Some impurities were observed in both joints by technical problems.

• Pediatric Infection and Vaccine
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• v.5 no.2
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• pp.289-295
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• 1998

Group B Streptococcal sepsis and/or meningitis is one of the most serious and common diseases in the neonatal period with high mortality and frequent complications. We have experienced a case of late onset type group B streptococcal sepsis and meningitis with a complication of subclavian vein catheterization catheterization. This 29-day-old male neonate was admitted to intensive care unit with the presentation of fever and septic shock. He was born with Cesarean delivery at 36 weeks and 3 days of gestational age. He showed multiple episodes of seizure after admission and group B streptococcus was isolated from blood. CSF profiles 10 days after admission showed the features of bacterial meningitis without organism isolated. Diffuse cerebral infarction was detected on brain CT 24 days after admission. In the 13th hospital day, the complication of subclavian vein catheterization occurred; Guide wire was cut during insertion and the distal portion of it(2.5cm) was retained in the left subclavian vein. We removed the retained guide wire with goose-neck snare catheter via right femoral vein. This case was presented with a brief review of the literatures.