• 한국정밀공학회지
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• 제18권7호
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• pp.98-105
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• 2001

The machining accuracy is affected by geometric, volumetric errors of the machine tools. To improve the product quality, we need to enhance the machining accuracy of the machine tools. To this point of view, measurement and inspection of finished part as error analysis of machine tools ahas been studied for last several decades. This paper suggests the enhancement method of machining accuracy for precision machining of high quality metal reflection mirror or optics lens, etc. In this paper, we study 1) the compensation of linear pitch error with NC controller compensation function using laser interferometer measurement, 2) the method for enhancing the accuracy of NC milling machining by modeling and compensation of volumetric error, 3) the spherical surface manufacturing by modeling and compensation of volumetric error of the machine tool, 4) the system development of OMM without detaching work piece from a bed of machine tool after working, 5) the generation of the finished part profile by OMM. Furthermore, the output of OMM is compared with that of CMM, and verified the feasibility of the measurement system.

• 한국산학기술학회논문지
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• 제7권3호
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• pp.506-511
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• 2006

은은 주조성과 가공성이 뛰어나 장신구 제작에 주된 소재로 채택되어 왔다. 이런 은 소재 자체의 장점을 이용한 전통적인 방법 중 하나인 모꾸메가네는 나뭇결무늬와 같은 자연스러운 금속의 혼합문양을 표현할 수 있어서 부가가치가 높지만 제작 공정이 복잡하고 힘들어서 경제적으로 장신구를 제작하는데 어려움이 있었다. 기존의 모꾸메가네 공정 대신 은과 구리의 융점차를 이용한 변형 주조 방법과 냉간압연으로 구리와 은 두 금속간의 우수한 결합을 유지하면서도 기존의 모꾸메가네와 유사한 표면 장식 효과를 얻을 수 있는 새로운 공정을 제안해 보았다. 직경 3 mm의 구리 그래뉼과 0.5 mm, 1.5 mm 두께의 구리 판재에 순은 용탕을 부어 두 금속간의 확산 접합이 완성된 괴를 만들고, 이후 롤러 압연을 실시하여 두께 1.5 mm의 판재를 만들어서 이를 이용하여 반지 시제품을 제작한 결과, 제안된 공정으로 이종 금속 접합도가 우수하면서 모꾸메가네와 유사한 효과를 성공적으로 낼 수 있었다. 제안된 공정은 기존의 반복된 열간 가공에 의한 복잡한 모꾸메가네 공정에 비해 보다 간단하고 경제적으로 모꾸메가네 효과를 갖는 은 장신구 디자인을 가능하게 함을 확인하였다.

• Progress in Superconductivity
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• 제9권1호
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• pp.102-106
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• 2007

YBCO films have been synthesized using a spray pyrolysis method. We used nitrates of Y, Ba, Cu as precursors. Deposition was made on $LaAlO_3$ (100) single crystal substrate by spraying the mist of aqueous precursor solution generated by a concentric nozzle. The distance between concentric nozzle and substrate was 15 cm. C-axis oriented films were obtained at deposition temperature of $740{\sim}800^{\circ}C$ and working pressure of 20 Torr. Oxygen partial pressure was 3 Torr and substrate was transported with the speed ranging from 0.23 cm/min to 0.7 cm/min by reel to reel. Scanning electron microscope (SEM) and X-ray diffraction (XRD) observation revealed that films are smooth and highly textured with (001) planes parallel to substrate. Highest critical current density (Jc) was $1.38\;MA/cm^2$ at 77K and self-field for the film with a thickness of $0.5\;{\mu}m$ prepared at a substrate temperature of $780^{\circ}C$ and $PO_2\;=3\;Torr$. The effect of temperature on the microstructure and YBCO phase formation will be discussed.

• 대한기계학회논문집
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• 제9권6호
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• pp.777-787
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• 1985

본 논문에서는 스트레치 플랜징과 슈링크 플랜징에 대하여 각 공정에서의 성 형한계를 이론적으로 구하여 이를 실험과 비교검토함으로써 효과적인 성형한계예측 방 법을 개발하는데 주안점이 있다. 스트레치 플랜징의 경우는 Wang과 Wenner의 연구에 서 얻어진 결과를 이용하여 여기에 기본적인 네킹(Necking)이론을 적용하여 성형한계 를 구하도록 한다. 한편 슈링크 플랜징의 성형한계 해석을 위해서는 Wang과 Wenner 의 스트레치 플랜징에 대한 해석방법을 응용발전시켜 응력 및 변형도등을 계산하고 주 름현상해석을 위해서 Yu 및 Johnson이 도입했던 좌굴계수(Buckling Modulus)개념을 이 용하여 미소 각변위(angular displacement)동안 플랜지부에서 생기는 굽힘에너지와 소 성변형에너지를 비교하는 판별조건을 써서 슈링크 플랜징의 성형 한계를 해석하고자 한다.아울러 각 공정에서의 이론 해석결과들을 성형실험에서 얻어진 값들과 비교 검토하도록 한다.

• Journal of Microbiology and Biotechnology
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• 제29권12호
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• pp.1916-1924
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• 2019

Outbreaks of staphylococcal food poisoning (SFP) causing serious human diseases and economic losses have been reported globally. Furthermore, the spread of Staphylococcus aureus with increased resistance to multiple antimicrobial agents has become a major concern in the food industries and medicine. Here, we isolated an endolysin LysSAP8, as one of the peptidoglycan hydrolases, derived from the bacteriophage SAP8 infecting S. aureus. This endolysin was tagged with a 6×His at the C-terminal of the target protein and purified using affinity chromatography. LysSAP8 demonstrated lytic activity against a broad spectrum of bacteria, which included a majority of the staphylococcal strains tested in this study as well as the methicillin-resistant S. aureus (MRSA); however, no such activity was observed against other gram-positive or gram-negative bacteria. Additionally, LysSAP8 could maintain bactericidal activity until 0.1 nM working concentration and after heat treatment at 37℃ for 30 min. The ability of LysSAP8 to lyse cells under varying conditions of temperature (4-43℃), pH (3-9), and NaCl concentrations (0-1,000 mM), and divalent metal ions (Ca²⁺, Co²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Hg²⁺, and Zn²⁺) was examined. At the optimized condition, LysSAP8 could disrupt approximately 3.46 log CFU/ml of the planktonic cells in their exponential phase of growth within 30 min. In this study, we have suggested that LysSAP8 could be a potent alternative as a biocontrol agent that can be used to combat MRSA.

• Design & Manufacturing
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• 제7권1호
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• pp.45-49
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• 2013

Since the shell-molds are used to make casting the metal parts for the automobile industry, the quality may well be inconsistent with the lower productivity, increasing the cost of the end products. The primary elbow design shell molded steel castings being produced through extrusion process has $180^{\varnothing}$ O.D., $150^{\varnothing}$ I.D., 14mm thickness and 400mm length, while being processed onto the left side of the tubing. The primary cause for the poor processing is the uneven manual shell molding. If the manual shell molds should be produced to have even quality, they would not be processed for tube linking. The purpose of this study was to develop the flask-molds for manufacturing of the shell molds to ensure mass-production, consistent quality, ommission of processing and comfortable working environment. For this purpose, four flask-molds were produced and thereby, four shell molds were assembled. In particular, the shell molds for processing were formed of the fine coated sand to be blown. As a result, productivity increased about three times, while a consistent quality was ensured. Furthermore, the tubes could be linked with each other without being processed, while pallets could be stacked, stored, transported and managed more easily. In a nut-shell, the molding theory could be applied more effectively. However, it is conceived that this study should be followed up by future studies which will research into reliability and endurability of the end products.

• 소성∙가공
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• 제23권8호
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• pp.489-494
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• 2014

Micro forming is an appropriate process to manufacture very small metal parts which can be employed in the field of electronic devices or electrically controlled mechanical systems. The purpose of the current study was to investigate the influences of both blankholding force and blank diameter for the deep drawing of very small cups. It is essential to control the blankholding force because improper force can result in defects such as wrinkles in the flange or cracks in the corner of the drawn cups. In the current study blankholding force was controlled by springs connected to the blankholder of a press die. Exchangeable bushing dies with various die-corner radii were also used. To obtain the limit drawing ratio for each working condition several sizes of circular specimens were prepared using blanking tools. Beryllium copper(C1720) alloy sheet of $50{\mu}m$ thickness was chosen for the experiments. The maximum limit drawing ratio of 2.1 was achieved experimentally for the conditions of the blankholder force(BHF)=5.3kgf and Rd=0.3mm. Both thickness and hardness along the central section of drawn cups were measured and compared for different drawing conditions. It was found that the deviation of measured data in the thickness and hardness distribution increases with increasing blankholder force and blank diameter.

• 한국세라믹학회지
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• 제43권1호
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• pp.22-27
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• 2006

The electronic band structures of Metal-doped titanium dioxide, M-doped $TiO_2$ (M=Co, Cr, Fe), have been studied by using XRD, UV-vis diffuse reflectance spectrometer and FP-LAPW (Full-Potential Linearized Augmented-Plane-Wave) method. The UV-vis of M-doped $TiO_2$ (M=Co, Cr, Fe) showed two absorption edges; the main edge due to the titanium dioxide at 387 nm and a shoulder due to the doped metals at around 560 nm. The band gap energies of Co, Cr and Fe-doped $TiO_2$ calculated by FP-LAPW method were 2.6, 2.0, and 2.5 eV, respectively. The theoretically calculated band gap energy of $TiO_2$ by using FP-LAPW method was the same as experimental results. FP-LAPW method will be useful for fabrication and development of photo catalysts working under visible light.

• 대한치과기공학회지
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• 제23권2호
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• pp.75-93
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• 2002

This research was preformed for the purpose of preparing the items of standard model of the national dental technician test base on the duty analysis of the dental technician. The results of the duty analysis for the dental technician follows. 1. The dental technician is a profession to make the oral function smooth through the dental supplement and equipment in a scientific method and the skilled technique. 2. The duty of the dental technician are determined as A. preparation for manufacture B. manufacture C. management of the place of the dental technology D. self-development. A. The field of "the preparation for manufacture" are determined as 1. to confirm work authorization 2. To confirm the working model, B. The field of "In manufacture" are determined as 1. to manufacture the temporary crown 2. to manufacture the inlay and crown & bridge prosthesis 3. to manufacture the porcelain fused metal crown prosthesis 4. to manufacture the all ceramic crown prosthesis 5. to manufacture the temporary denture prosthesis 6. to manufacture the partial denture prosthesis 7. to manufacture the complete denture prosthesis 8. to manufacture the attachment prosthesis 9. to manufacture implant prosthesis 10. to manufacture the removable orthodontic device, 11. to manufacture the fixed orthodontic device, 12. to manufacture the orthodontic study cast C. The field of "in management of the dental lab." are determined as 1. management 2. to control the dental lab. D. The field of "In the self-development" are determined as 1. to improve the professionalism 2. self-control. 3. The developing items selected under the duty evaluation of the dental technician are l7s in the manufacture preparation, 1,011s in the manufacture, 7s in the management for the dental technology, 5s in self-development, and in all together 1,040s

• 전자공학회논문지C
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• 제35C권12호
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• pp.66-76
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• 1998

본 논문에서는 명령어 버퍼에 저장되어 있는 가변 길이 명령어의 미스 율을 낮추기 위한 버퍼를 구현한다. 또한 반복적으로 수행되는 명령어들의 디코딩 시간을 줄이기 위해 외부에서 명령어를 패취(fetch)하여 초기 디코드 동작을 한 후 그 결과를 버퍼에 저장하는 MAU(Mark Appending Unit)를 둔다. 또한 분기명령어의 효과적인 처리를 위해 타겟 명령어의 히트 여부를 판단하는 회로를 내장하고 있다. 가변 길이 명령어를 처리하기 위한 각 모듈은 VHDL을 이용해 설계되었으며, Model Technology Inc.의 V-System를 사용하여 시뮬레이션 하였다. 합성 및 검증은 0.6㎛ 5-Volt CMOS TLM(Three Layer Metal) COMPASS 라이브러리를 이용한 ASIC Synthesizer 툴을 사용하였다. 최고 동작 속도는 약 140MHz까지이며, 총 게이트 수는 약 17,000개이다.