• Applied Science and Convergence Technology
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• 제23권3호
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• pp.145-150
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• 2014

MgO thin films were deposited by internal ICP-assisted reactive-magnetron sputtering with bipolar pulse bias on a substrate to suppress random arcs. Mg is reactively sputtered by a bipolar pulsed DC power of 100 kHz into ICP generated by a dielectrically shielded internal antenna. At a mass flow ratio of $Ar/O_2$ = 10 : 2 and an ICP/sputter power ratio of 1 : 1, optimal film properties were obtained (a powder-like crystal orientation distribution and a RMS surface roughness of approximately 0.42 nm). A bipolar pulse substrate bias at a proper frequency (~a few kHz) prevented random arc events. The crystalline preferred orientations varied between the (111), (200) and (220) orientations. By optimizing the plasma conditions, films having similar bulk crystallinity characteristics (JCPDS data) were successfully obtained.

• 한국전기전자재료학회논문지
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• 제20권11호
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• pp.1004-1008
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• 2007

The ice coats are built on 25 kV overhead contact wire when the temperature is lower than $0^{\circ}C$. It generates shockwaves at the mechanical interface of the collecting strips of the pantograph and the contact wire. The de-icing processes should be performed to avoid shockwaves which are generated by a pulsed high-voltage arc discharge. This paper presents temperature analysis of the de-icing effects which could be applied to the overhead contact wire of railways using Joule heat. The results show that 350 A is the proper current for $0^{\circ}C$ conductor according to environmental condition such as velocity of air stream, ambient temperature and moisture.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.499-503
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• 2004

This application-oriented paper describes an automated welding carriage system to weld a thin corrugated workpiece with welding seam tracking function. Hyundai Heavy Industries Corporation has developed an automatic welding carriage system, which utilizes pulsed plasma arc welding process for corrugated sheets. It can obtain high speed welding more than 2 times faster than traditional TIG based welding system. The aim of this development is to increase the productivity by using automatic plasma welding carriage systems, to track weld seam line using vision sensor automatically, and finally to provide a convenience to operator in order to carry out welding. In this paper a robust image processing and a distance based tracking algorithms are introduced for corrugated workpiece welding. The automatic welding carriage system is controlled by the programmable logic controller(PLC), and the automatic welding seam tracking system is controlled by the industrial personal computer(IPC) equipped with embedded OS. The system was tested at actual workpiece to show the feasibility and performance of proposed algorithm and to confirm the reliability of developed controller.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권2호
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• pp.120-124
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• 2000

In this paper, the effect of magnetic field was measured on NOx(NO+NO2) removal and consumption power for wire-plate plasma reactor with magnetic field applied to electric field vertically. NOx of the simulated diesel engine flue gas were removed by the corona discharge generated by DC, AC and Pulsed voltages in wire-plate reactor. Consumption power increased with discharge voltage. However, when magnetic field was applied to electric field vertically, consumption power slightly decreased. NOx removal rate and arc transition voltage for plasma reactor with magnetic field were higher than those for plasma reactor without magnetic field. Consumption power decreased, however NOx removal significantly increased, when water vapour bubbled by dry air was put into simulated flue gas.

• 공업화학
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• 제19권3호
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• pp.270-276
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• 2008

$TiO_2$의 가장 큰 특징은 광촉매적 특성을 들 수 있으나 순수한 $TiO_2$는 자외선 영역에서만 활성을 보이는 단점이 있다. 단점을 보완하고자 본 연구에서는 초고온, 고활성을 이용한 열플라즈마 공정으로 질소가 도핑된 $TiO_2$를 합성하여 $TiO_2$의 광촉매적 특성을 높이고자 하였다. 직류 플라즈마 제트를 이용하여 비금속이온인 질소와 반응 가스인 산소를 $TiCl_4$와 함께 플라즈마 반응기 안에서 반응시켜 질소가 도핑된 $TiO_2$ 나노 분말을 합성하였다. 합성 조건으로 질소의 유량을 변화하였다. 합성 변수에 따른 입자의 상조성, 크기를 분석하였고 아세트알데히드와 곰팡이를 광분해하는 실험을 통해 광촉매 활성을 살펴보았다. 한편 $TiO_2$의 분말 상태와 코팅된 상태의 광촉매 특성을 비교하고자 합성한 분말의 스핀 코팅과 PLD (Pulsed Laser Deposition)을 통해 $TiO_2$를 코팅하였다. 아세트알데히드 분해 실험의 결과 질소가 도핑된 $TiO_2$ 분말의 경우가 순수한 $TiO_2$ 분말에 비해 가시영역에서의 광촉매 활성이 두 배 이상 뛰어난 것을 확인하였으며, 곰팡이 분해 실험 결과 역시 질소가 도핑된 $TiO_2$ 분말에 곰팡이가 분해되는 것을 확인하였다. 분말과 필름을 제조하여 메틸렌블루 광분해 실험한 결과 분말의 경우 100% $TiO_2$입자가 메틸렌블루 분해에 이용되며, 반면 스핀 코팅의 경우 바인더의 함량 때문에 20~30%의 $TiO_2$만이 분해에 이용되기 때문에, 분말의 경우 초기 30 mL 메틸렌블루를 한번에 분해할 수 있었다.

• 한국재료학회지
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• 제15권4호
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• pp.257-262
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• 2005

Nano-sized ZrVFe alloy powders were prepared by the ablation of powder compact in alcobol using a Nd-YAG pulsed Laser. The $Zr_{57}V_{35.}8Fe_{7.2}$ alloy commercially designated as ST707 has long been known as the ideal solution for various vacuum applications. The target for the ablation was sintered pellets of $Zr_{57}V_{35.}8Fe_{7.2}$ alloy powder. The alloy was prepared by arc melting and Hydride-DeHydride method. The ablated powders were mostly circular having fairly large size distribution smaller than 200 nm in all cases. The X-ray diffraction study revealed that the ablated alloy retained the crystal structure of the target alloy. Nevertheless, Fe and V contents in the ablated powder were lower than those in the target alloy. This was believed to result from the high vapour pressures of Fe and V compared to that of Zr. The size of the powders ablated at high energy fluence tends to decrease due at least partly to the breakdown of previously made ones.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1627-1627
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• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M^{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima t and the variation of full width at half maximum w were strongly dependent on the detection position and the wavelength of the laser beam. At, t and w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1626-1626
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• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M_{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima $\Delta$t and the variation of full width at half maximum Δw were strongly dependent on the detection position and the wavelength of the laser beam. At, $\Delta$t and $\Delta$w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• 자원리싸이클링
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• 제7권1호
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• pp.27-33
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• 1998

유리질산 및 불산이 제거된 산세폐액으로부터 Ni을 회수하기 위하여 컬럼식 연속추출장치에 의한 연속실험을 수행하였다. 먼저 Ni 회수 실험에 앞서 폐액중 다량 함유되어 있는 Fe나 Cr을 효과적으로 침전 제거하기 위해서는 중화제로 $CaCO_3$가 적절하며 이대 Ni은 전혀 침전되지 않는다. 한편 컬럼식 연속추출장치에 의한 No의 추출특성을 살펴보면 pulse velosity(Amplitude$\times$Frequency)가 증가함에 따라 수상과 유기상의 혼합효과가 증대되어 Ni의 추출율이 높아지고 이에 딸 HETS도 감소하고 있으나, pulse velosity가 임계치 이상으로 증가하게 되면 수상과 유기상의 강력한 혼합에 의해 원판과 원판사이에 분리층이 형성되지 못하고 컬럼 전체가 완전한 혼합 형태로 되어 추출율이 낮아지고 HETS도 길어지게 된다. 유기상에 추출된 Ni은 탈거시 탈거액으로 2M ${H}_{2}{SO}_{4}$액을 사용하면 효과적으로 농축 회수할 수 있다. 그리고 ${H}_{2}{SO}_{4}$용액중 $NiSO_4$의 용해도는 ${H}_{2}{SO}_{4}$ 농도가 증가함에 따라 감소하여 2M ${H}_{2}{SO}_{4}$ 용액에서는 55 gr/$\ell$ 정도로 나타나고 있으며, 이같은 $NiSO_4$의 과포화특성을 이용하면 탈거액의 증발과정을 거치지 않고 $NiSO_4$결정을 얻을 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.117-117
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• 2010

나노입자 제조 기술이 점차 발전하면서 금속산화물, 반도체용 및 태양전지용, 신소재 등 다양한 응용분야에 사용하고 있다. 따라서 이와 같은 나노입자 제조방법으로는 펄스 레이저 용사법(pulsed laser ablation), 플라즈마 아크 합성법(plasma arc synthesis), 열분해법(pyrolysis), plasma-enhanced chemical vapor deposition (PECVD)법 등과 같은 기상공정이 많이 사용되고 있다. 기상공정은 기존의 공정에 비해 고순도 입자의 대량 생산, 다성분 입자의 화학적 균질성 유지, 비교적 간단하고 깨끗한 공정 등의 장점을 가지고 있다. 기상공정에서 일반적인 입자 형성 메커니즘은 기체 상태의 화학 물질이 물리적 공정 혹은 화학 반응에 의해 과포화상태에 도달하게 되며, 이 때 동질 핵생성(homogeneous nucleation)이 일어나고 생성된 핵(nuclei)에 기체가 응축되고 충돌, 응집하면서 입자는 성장하게 된다. 열분해법은 실리콘 나노입자를 생산하는 기상공정 중 하나이다. 일반적으로 열분해 공정은 지속적으로 열이 가해지는 반응기 내에 반응기체인 $SiH_4$을 주입하고, 운반기체는 He, $H_2$, Ar, $N_2$ 등을 사용하였을 때, 높은 열로 인해 $SiH_4$가 분해되며, 이 때 가스-입자 전환 현상(gas to particle conversion)이 일어나 실리콘 입자가 형성된다. 그러나 입자 형성과정은 $SiH_4$ 농도, 유량, 작동 압력, 온도 등 매우 다양한 요소에 영향을 받는다. 고, 복잡한 화학반응 메커니즘에 의해 명확히 규명되지는 못하고 있다. 이에 본 연구에서는 복잡한 화학반응을 해석하는 상용코드 CHEMKIN 4.1.1을 이용하여 열분해 반응기 내에서의 실리콘 입자 형성, 성장, 응집, 전송 모델을 만들고 이를 수치해석하였다. 표면 반응, 응집, 전송에 의한 입자 성장 메커니즘을 포함하고 있는 aerosol dynamics model을 method of moment법으로 해를 구하였으며, 이를 실험 결과와 비교하여 모델링을 검증하였다. 또한 반응기의 온도, 압력, 가스 농도, 유량 등의 요소를 고려하여 실리콘 나노입자를 형성하는 최적의 조건을 연구하였다.