• 한국자기학회지
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• 제27권2호
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• pp.49-53
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• 2017

THz 대역 전파흡수체를 구현하기 위해 split cut wire(SCW)와 배면 도체로 구성되는 단위 셀 구조를 제안하였다. 배면이 금속으로 단락된 유전체 기판 상에 SCW가 배열된 메타소재에서 SCW의 길이와 폭을 조절하여 THz 대역에서 완전 전파흡수체(5.5~6.0 THz에서 반사손실 -20 dB 이하)의 구현이 가능하였고, 인덕턴스-커패시턴스 (L-C) 공진기 회로이론으로 이를 설명하였다. 길이가 서로 다른 두 개의 SCW를 하나의 단위 셀 안에 같이 배치함으로써 두 개의 흡수 피크를 얻을 수 있었다. SCW 간의 간격이 넓어짐에 따라 두 번째 공진주파수는 거의 변화가 없지만 첫 번째 공진주파수는 저주파로 이동하면서 반사손실 값이 현저히 감소하는 경향이 나타났다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.537-542
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• 2000

Wire deflection, surface roughness and roundness were observed on changing discharge time for electrical discharge machining(EDM) of STD-11 in various conditions of thickness. The wire deflection was decreased as increasing discharge time and wire tension. The deflection is the smallest at the speed of wire of 10.6m/min and the water specific resistivity of 5k$\Omega$.cm. The deflection is found to be decreased as increasing dwell time. But if the water pressure is high, it is found not to be changed after the vibration of 4sec. The component of copper(Cu) and zinc(Zn), which is the main material of wire electrode, is observed for rough wire-cutting EDM of STD-11. This phenomena is found to be similar in spite of the change of EDM energy level. But it will be improved by changing the material and the shape of wire. The roundness of middle is found to be worse than that of upper and it is increased as the thickness of material is increased.

• 한국정밀공학회지
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• 제5권4호
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• pp.59-65
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• 1988

This paper describes the transmutation layer of CNC Wire electrical discharte machined surface. In order to analayze and invesigate transmutation layer of the carbon tool steel, workpieces was heat-treated by quenching, tempering, normaling. The obtained results are summarized as follows. 1. The result showed that wire electrical discharge machined surface region was transmuted into the recdast layer in the range of about 10${\mu}$m deep by resolidification and next zone was transmuted into the heat affected zone in the range of about 15${\mu}$m deep by high temperature. 2. The hardness of the recast layer and heat affected zone was decreased on its machined surface. 3. The more wire feedrate was increased, the more electrical discharge machine gap was decreased.

• 한국정밀공학회지
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• 제21권11호
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• pp.171-178
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• 2004

This paper presents vibration characteristics of a wire cut discharge machine in which an electro-rheological brake actuator is used to control the wire tension. The ER brake actuator has several advantages including design simplicity, fast response time and real-time controllability. On the basis of the tension level required in the machine an appropriate size of the ER brake actuator is devised. The ER brake actuator is then incorporated with the machine and the field-dependent wire tension is experimentally evaluated. The straightness of the workpiece is also empirically investigated by changing the intensity of the electric field.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.820-823
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• 2000

The characteristics of wire deflection, surface roughness and roundness were observed on changing discharge time for electrical discharge machining(EDM) of tungsten carbide in various conditions of thickness. The wire deflection was decreased as increasing discharge time and wire tension, the gap of deflection was decreased after thickness 60mm and discharge time of 6$\mu\textrm{s}$ due to the changing from fundamental mode to vibration mode. The deflection is the smallest at the water specific resistivity of 7.5 kΩ ㆍcm. The deflection is found to be decreased as increasing dwell time, and the result is due to the vibration of the pressure and the amount of the dielectric. The component of copper(Cu) and zinc(Zn), which is the main material of wire electrode, was observed for rough wire-cutting EDM of STD-11. This phenomena is found to be decreased as the number of EDM is increased. But it will be improved by changing the material and the shape of wire. The roundness of middle is found to be worse than that of upper and it is increased as the thickness of material is increased.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.875-878
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• 1997

Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though it is very hard material and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods.

• Journal of Magnetics
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• 제21권2호
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• pp.187-191
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• 2016

Retrieving the equivalent electromagnetic parameters (permittivity and permeability) plays an important role in the research and application of metamaterials. Frequency dispersion of magnetic permeability has been theoretically predicted in a metamaterial composed of cut wire pairs (CWP) separated by dielectric substrate on the basis of circuit theory. Magnetic resonance resulting from antiparallel currents between the CWP is observed at the frequency of minimum reflection loss (corresponding to absorption peak) and effective resonator size can be determined. Having calculated the circuit parameters (inductance L, capacitance C) and resonance frequency from CWP dimension, the frequency dispersion of permeability of Lorentz like magnetic response can be predicted. The simulated resonance frequency and permeability spectra can be explained well on the basis of the circuit theory of an RLC resonator.

• 한국전자파학회논문지
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• 제25권3호
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• pp.339-347
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• 2014

본 논문에서는 유연성 기판을 이용한 새로운 광대역 메타물질 구조의 흡수체를 제안하였다. 제안된 메타 물질 구조의 단위 셀은 유연성 있는 폴리이미드 기판 위의 동일 평면상에 놓여진 ELC 공진기와 cut-wire 구조로 이루어졌으며, 설계 주파수 대역 밖에서 레이더 단면적(RCS) 값을 감소시키기 위하여 제안된 구조의 금속 패턴 층은 입사 전자파의 진행 방향과 평행하게 놓았다. 총 $33{\times}45$개의 단위 셀들의 배열로 이루어진 흡수체 시작품을 제작하고, 측정한 결과, 주파수 9.06 및 15.0 GHz에서 각각 92 % 및 93 % 이상의 최대 흡수율과 75 %의 full-width at half-maximum 대역폭을 나타내었다. 제안된 금속 접지 판이 없는 메타물질 구조는 마이크로파 주파수대 광대역 흡수체로 곡면 구조에도 응용이 가능하다.

• 동아시아식생활학회지
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• 제26권5호
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• pp.450-456
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• 2016

과당의 이성체인 알룰로오스가 저혈당 및 저칼로리효과를 갖는 건강쿠키를 제조하는데 설탕대체제로 이용이 될 수 있는지 평가하였다. 설탕(대조군), 과당, 포도당, 알룰로오스를 사용하여 이들 설탕대체제들의 효과를 SRC, DSC, RVA, 와이어 컷 쿠키 방법으로 평가하였다. SRC 결과에서 용액에 접근 가능한(solvent-accessible) 아라비노자일란이 다른 당용액에 비해 알룰로오스에서 가장 적게 부푸는 것으로 관찰되었다. DSC와 RVA 결과들에서 각각 밀가루 전분의 호화 및 전분 pasting의 개시가 모두 물 < 알룰로오스 < 과당 < 포도당 < 설탕의 순서로 지연됨을 알 수 있었다. 사용한 당 중에서 포도당으로 만든 쿠키가 지름과 두께 측면에서 가장 선호되지 않는 특성을 나타냈다. 알룰로오스의 쿠키 베이킹 적성은 설탕에 비해 조금은 부족하지만 과당보다는 뛰어나 과당대 체제로나 설탕대체제로 저칼로리 저혈당효과가 있는 쿠키를 제조하는데 성공적으로 이용될 수 있음을 시사하였다.

• 한국산업융합학회 논문집
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• 제25권2_2호
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• pp.263-269
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• 2022

In this study, the optimal support position determination and stability determination of the wedge wire screen were performed for the production of the wedge wire filter screen with improved mesh screen. In order to manufacture a filter screen using a wedge wire, the support rod wedge wire is first installed according to the filtering capacity, and then spot welding is performed while rotating the profile wire. In the existing manufacturing method, it was manufactured using a 3m rod wedge wire and then cut according to dimensions, but it required the manufacture of a 6m cylindrical screen. Due to the increase in wedge wire length, it is difficult to manufacture stress concentration at sagging and fixed positions. In order to shorten the time of analysis, a single wedge wire was applied instead of a plurality of wedge wires. The reliability and validity of the interpretation were presented and the results were derived. After selecting the support point at the 2m position, structural analysis was performed on the entire filter screen to confirm stability.The purpose of this study is to identify the maximum deflection of the wire for the production of a 6m wedge wire screen and secure design basic data so that it can work safely through optimal support.