• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.104-107
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• 2002

Direct Metal Manufacturing (DMM) is a new additive process that aims to take die making and metalworking in an entirely new direction. It is the blending of five common technologies : lasers, computer-aided design (CAD), computer-aided manufacturing (CAM), sensors and powder metallurgy. The resulting process creates parts by focusing an industrial laser beam onto a tool-steel work piece or platform to create a molten pool of metal. A small stream of powdered tool-steel metal is then injected into the melt pool to increase the size of the molten pool. By moving the laser beam back and forth, under CNC control, and tracing out a pattern determined by a computerized CAD design, the solid metal part is built line-by-line, one layer at a time. DMM produces improved material properties in less time and at a lower cast than is possible with traditional fabrication.

• Korean Journal of Computational Design and Engineering
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• v.9 no.4
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• pp.373-381
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• 2004

Using standard components of a press die is recognized as a way for a cost reduction and a short lead time. It also provides a way for a quick maintenance of a die under repair. It is expected to contribute to integration of CAD/CAM system for manufacturing dies in the future. This paper presents a 3D CAD library which is constructed using the standard components and is used for designing a press die. This 3D CAD library is generated by a database system made of Microsoft Access for standard components and by CATIA V5 R10 API for geometric features. The library is implemented using Visual Basic 6.0 utility of CATIA API function in the Windows NT environment. It creates a 3D model of the standard components of press die easily when a die designer inputs numerical values of geometric features and the BOM of the completely assembled parts. It also generates automatically the assembly drawing of die set by using variables for standard values of die parts. Therefore users can save the cost of time to design the press die components, and even a beginner can use this program with ease. The test results of the 3D CAD library for designing shearing and bending dies verify its usefulness and feasibility.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.11
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• pp.1-6
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• 2002

This study is about optimization of Laser Repair Condition in EDS Line to improve AC and DC characteristic of high speed DRAM. The margin of AC parameter can be improved by forcing the proper DC generator levels and also improved by cutting the optional fuse about characteristics.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.151-155
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• 2002

Memory의 공정기간은 2∼3개월 정도, 공정은 수백가지에 이를 정도로 많기에 defect은 존재할 수밖에 없다. 많은 defect이 있다면 어쩔 수 없겠지만 적은 defect이 발생한 경우에는 해당 die를 reject시키는 것보다는 repair해서 사용하는 것이 memory생산 업체 입장에서는 보다 효율적이고 원가 절감 차원에서 필수적이다. 이와 같은 이유로 laser repair라는 공정이 필요하고 laser repair공정의 정확한 target을 설정하기 위해 redundancy analysis가 필요하게 되었다. 지금까지 redundancy analysis는 장비 개발 업체에서 제공하는 경우가 대부분 이었고 각 장비 제조 업체별로 redundancy analysis algorithm을 개발하여 제공하여왔기에 동일한 defect 유형에 분석하는 redundancy analysis time이 각 장비 업체 별로 다른 경우가 대부분이었다. 이에 본 연구에서는 기존의 redundancy analysis algorithm의 개념에서 벗어나 defect 유형별로 simulation한 후 redundancy analysis를 진행함으로써 redundancy analysis에 소요되는 시간을 절약함으로써 원가 경쟁력 강화를 하고 correlation 개념을 업무에 적용하는데 목적이 있다

• Journal of Welding and Joining
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• v.28 no.3
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• pp.79-85
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• 2010

Hardfacing is one of the frequently applying method to increase surface hardness in hot forging die. Recently, hardfacing receives great attention due to it's repair availability and low cost. In hot forging die, crack resistance and thermal shock resistance have been considered as major properties, However there are few studies for the assessment of these properties. So, it is necessary to establish the assessment method for crack resistance and thermal shock resistance in hardfacing for hot forging die. In this study, flux cored arc welding was applied to make hardfacing welds. Three point bending test was carried out to assess hardfacing weld's crack resistance, and high temperature bending test using salt bath was developed for thermal shock resistance. Consequently, it was possible to assess crack resistance and thermal shock resistance of hardfacing welds for hot forging die quantitatively.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.331-340
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• 2012

In the deep sub-micron ICs, growing amounts of on-die memory and scaling effects make embedded memories increasingly vulnerable to reliability and yield problems. Spare columns are often included in memories to repair defective cells or bit lines during production test. In many cases, the repair process will not use all spare columns. Schemes have been proposed to exploit these unused spare columns to store additional check bits which can be used to reduce the miscorrection probability for triple errors in single error correction-double error detection (SEC-DED). These additional check bits increase the dimensions of the parity check matrix (H-matrix) requiring extra area overhead. A method is proposed in this paper to efficiently fill the extra rows of the H-matrix on the basis of similarity of logic between the other rows. Optimization of the whole H-matrix is accomplished through logic sharing within a feasible operating time resulting in reduced area overhead. A detailed implementation using fuse technology is also proposed in this paper.

• Journal of Korean Neurosurgical Society
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• v.65 no.6
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• pp.841-845
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• 2022

Objective : Chiari III malformations are extremely rare hindbrain malformations that are associated with a high early mortality rate, or severe neurologic deficits in the survivors. The treatment is early operative closure and cerebrospinal fluid diversion (CSF) shunting. Methods : We operated on 15 patients by repair and excision between July 2014 till June 2020 and retrospective data collection was done. Only one patient doesn't need ventriculoperitoneal (VP) shunt and the other 14 patients need a VP shunt. We described stepwise dissection and untethering of the cerebellum from the bony edge to regrowth and herniation of cerebellum again into this potential space and simple dural closure or repair with graft was done. Results : We started with VP in eight patients (53%) and the other seven patients (46.7%) started with excision and then six patients need VP shunt later on because four patients developed CSF leak and two patients developed increased high intracranial tension. Only four patients (26.7%) needed a blood transfusion. Conclusion : There are variations in the outcome and not all cases of Chiari malformation III will die and severe developmental delay is not a must. Proper management and repair carry a good prognosis.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.71-81
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• 2009

Die steel for plastic molding were used as mold material of automobile parts and electronic component industry. The material of this paper has superior to mechanical properties, such as repair weldability, corrosion resistance and high temperature strength, required mold parts for semitransparent. Laser-induced surface hardening technology is widely adopted to improver fatigue life and wear resistance via localized hardening at the surface of mold parts. The objective of this research work is to investigate on the characteristics of surface hardening of the laser process parameters, such as beam travel speed, laser power and defocsued spot position, for the case of die steel for plastic molding. Lens for surface hardening of large area is plano-convex type with elliptical profile to maintain uniform laser irradiation. According to the experimental results, large size of hardened layer at the surface of die steel for plastic molding was achieved, and microstructure of this layer was lath martensite. Optimal surface status and mechanical property of hardened layer could be obtained at 1095Watt, $0.25{\sim}0.3m/min$, 0mm (focal length: 232mm) for laser power, beam travel speed, and focal position. Where, heat input was $0.793{\times}10^{3}J/cm^2$, and width of hardened layer was 27.58mm.

• CDE review
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• v.8 no.2
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• pp.47-52
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• 2002

레이저를 이용한 직접금속성형기술(영문명 : DMT: Direct Metal Tooling)은 고 부가가치의 기능성 소재(금속, 합금, 세라믹 등)의 미세한 분말을 원하는 3차원 공간상에 주사함과 동시에 이를 레이저로 직접, 순간 용착시키며 이것이 공간상에서 축적되가면서 미리 정해진 3차원 파트형상이 자동적으로 빌드업 되도록 하는 고도의 정밀제어 기술을 요하는 신기술이다. 이는 컴퓨터에 저장된 3차원 디지털 형상정보(digital data of 3D subjects)만 갖고 있으면 이로부터 그에 해당하는 금속파트형상을 적절히 소재분말을 이용하여 곧바로 실물로 재현하여 얻을 수 있게 됨을 의미하며 이로서 기존에 절삭기계를 이용한 가공 공법보다 손쉽고 빠르면서도 반면 기계적 성질은 종전기술보다 월등히 우수한 B차원 금속 파트나 금형 형상을 소재의 낭비가 전혀 없는 환경 친화적인 방법으로 제작할 수 있는, 소위 밀레니엄시대를 대표하는 최첨단 미래형 기술의 구현이다.

• Korean Journal of Veterinary Research
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• v.56 no.3
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• pp.193-195
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• 2016

The purpose of this report is to introduce persistent left cranial vena cava (PLCVC) with persistent right aortic arch (PRAA) and patent ductus arteriosus (PDA). Case 1 was a Cocker Spaniel with PRAA and case 2 was a Maltese with PDA. PLCVC was enclosed at the sites of PRAA and PDA surgery; therefore, it was lifted dorsally during PDA and PRAA surgery. Surgery to repair congenital heart defects including PRAA and PDA is recommended for dogs that do not die of PLCVC at a young age.