• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.63-70
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• 1983

Recently, many studies for developing the underwater welding techniques have been carried out in the advanced countries as a manufacturing process and a repairing method according as a great deal of interest in development for various marine industrial fields has been gradually increased. But no study on such underwater welding is available at present in our country. In this study, underwater welding was carried out for welding of domestic structural steel plates (SM41A) of 10 mm thickness, using six types of domestic coated arc welding electrodes on a self-made gravity type underwater welding device, resulting in investigation for the underwater weldability of the domestic structural steel plates as well as for the underwater welding properties and practicability of the domestic welding electrodes.

• Physical Therapy Korea
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• v.4 no.2
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• pp.36-50
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• 1997

The purpose of this study was to compare the effects of high intensity, high frequency microcurrent electrical neuromuscular stimulation(MENS) of auricular and somatic acupuncture points and low intensity, low frequency microcurrent electrical neuromuscular stimulation(MENS) of auricular and somatic acupuncture points on experimental pressure threshold at the elbow according to the time. Fifty healthy adults, aged 19 to 26 years, were assigned randomly to one of five groups: 1) the high intensity, high frequency somatic group(n=10) received MENS to somatic acupuncture points, 2) the high intensity, high frequency auricular group(n=10) received MENS to auricular acupuncture points, 3) the low intensity, low frequency somatic group(n=10) received MENS to somatic acupuncture points, 4) the low intensity, low frequency somatic group(n=10) receive MENS to somatic acupuncture points, and 5) the placebo group(n=10) received placebo treatment and served as controls. Pressure threshold was measured before, after, 5 minutes, 10 minutes and 15 minutes. Pressure threshold has increased significantly(p<.05) in the high intensity, high frequency auricular group following treatment after 5 minutes, with no statistically significant differences in pressure threshold change scores among five groups, Only the high intensity, high frequency auricular group demonstrated statistically significant change score in pressure threshold following treatment after, 5 minutes, 10 minutes and 15 minutes after compared to the placebo group. The results indicated that MENS applied to the high intensity, high frequency auricular group increases pressure threshold.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.535-541
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• 2013

The present study was carried out to investigate the effects of welding parameters such as current, voltage and shielding gases on the bead shape, microstructures and hardness. It was confirmed that bead height was lowered and bead depth was increased with increasing voltages while height, depth and width of beads increased with welding currents. The hardness of weld metals with Ar+10% $O_2$ and Ar+20% $CO_2$ was low due to the formation of grain boundary and polygonal ferrites while that of weld metals with Ar+2% $O_2$ was high due to the presence of acicular, bainitic and sideplate ferrites.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.221-226
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• 1998

Amorphous (Ba, Sr)$TiO_3$[BST] layer(30, 70 nm) was introduced between crystalline BST and $RuO_2$electrode to realize double-layered BST structure in order to improve the properties of BST film. The structure and surface morphology of double-layered BST film were modified by the application of amorphous BST layer; that is, surface became smoother and grain size increased abruptly. Amorphous layer thicker than 30 nm was effective to hinder the influence of $RuO_2$surface on the structure of as-grown BST films by in-situ process. Dielectric constant of double-layered BST film was improved dramatically from 152 to 340 and leakage current was lowered from $1.25{\times}10^{-5}A/{\textrm}{cm}^2);to;6.85{\times}10^{-7}A/{\textrm}{cm}^2$, respectively.

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.241-245
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• 2005

CoFeNi alloys are some of the most studied soft magnetic materials because of their applications as write-head core materials in HDD and MEMS. Ternary CoFeNi films with high saturation magnetic flux density, Bs and low coercivity, He were successfully grown by electrodeposition. The optimal composition was $Co_{30}\;Fe_{34}\;Ni_{36}(at\%)$, and Bs and Hc were 1.9 T and 0.16 A/m, respectively. The XRD and TEM results show that the low Hc of the CoFeNi films was due to very fine crystal particles and mixed fcc and bcc phases.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.359-364
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• 2019

The suspension plasma spraying is a modification of conventional plasma spray techniques that has been developed to overcome the challenge of using fine particles in plasma spray processes. In this study, microstructure developments and mechanical property of yttrium oxide (Y₂O₃) coatings prepared by the suspension plasma spray coating technique have been investigated to determine the effect of processing parameters including plasma gun current and total gas flow. The results showed that a highly dense Y₂O₃ coating having low porosity of 0.2 vol% without any lamellar structures can be achieved at the optimum condition of gun current 200 A and total gas flow 220 L/min.

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.775-781
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• 1999

Palladium thin films of uniform and highly dense microstructure were prepared by the eletroplating method using novel PdCl$_2$-based plating bath. Principal variables taken into account in this study were the plating temperature and the current density. Electroplated Pd films were characterized for Crystalline orientation, morphology and hardness. The optimal temperature and current density were found be $50^{\circ}C$ and 5mA/$\textrm{cm}^2$, repectively. The measured hardness value for the Pd films when prepared under the optimal condition was as high as 600kg/$\textrm{mm}^2$. A correlation study between variables and properties seems to indicate that the hardness was significantly affected by the microstructure, but not by crystallite orientation.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.106-106
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• 2000

반도체 소자가 미세화 됨에 따라 게이트 유전막으로 사용되는 SiO2의 박막화가 요구되나, boron penetration에 의한 Vt shift, 게이트 누설전류, 다결정 실리콘 게이트의 depletion effect 그리고 quantum mechanical effect 때문에 ~20 급에서 한계를 나타내고 있다. 이에 0.1$\mu\textrm{m}$이상의 design rule을 갖는 logic이나 memory 소자에서 요구되어지는 ~10 급 게이트 산화막은 SiO2(K=3.9)를 대신하여 고유전율을 갖는 재료의 채택이 필수 불가결하게 되었다. 고유전 박막 재료를 사용하면, 두께를 두껍게 해도 동일한 inversion 특성이 유지되고 carrier tunneling 이 덜하여 등가 산화막의 두께를 줄일 수 있다. 이러한 고유전박막 재료중 가장 활발히 연구되고 있는 재료는 Ta2O5, Al2O3, STO 그리고 BST 등이 있으나 Ta2O5, STO, BST 등은 실리콘 기판과 직접 반응을 한다는 문제를 가지고 있으며, Al2O3는 유전율이 낮의 재료가 최근 주목받고 있다. 본 실험에서는 ZrO2, HfO2 또는 그 silicates 등의 재료가 최근 주목 받고 있다. 본 실험에서는 ZrO2 박막의 증착조건에 따른 물리적, 전기적 특성 변화에 대하여 연구하였다. RCA 방식으로 세정한 P-type (100) 실리콘 기판위에 reactive DC sputtering 방법으로 압력 5mtorr, power 100~400W, 기판온도는 100-50$0^{\circ}C$로 변화시켜 ZrO2 박막을 증착한 후 산소와 아르곤 분위기에서 400-80$0^{\circ}C$, 10-120min으로 열처리하였다. 증착직후의 시편들과 열처리한 ZrO2 박막의 미세구조와 전기적 특성 변화를 관찰하였다. 우선 굴절율(RI)를 이용해 ZrO2 박막의 밀도를 예측하여 power와 기판온도에 따라 이론값 2.0-2.2 에 근접한 구조를 얻은 후 XRD, XPS, AFM, 그리고 TEM을 사용하여 ZrO2 박막의 chemical bonding, surface roughness 그리고 interfacial layer의 특성을 관찰하였다. 그리고 C-V, I-V measurement를 이용해 capacitance, 유전율, 누설전류 등의 전기적 특성을 관찰해 최적 조건을 설정하였다.

• Analytical Science and Technology
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• v.13 no.5
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• pp.565-572
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• 2000

In this paper it was described on the standards for Xe analysis by Wavelength Dispersive X-ray Spectrometer (WDS) of Electron Probe Micro Analyser. According to the experimental results, CsI and $BaCO_3$ are appropriate compounds as standard specimen for Cs, I and Ba which has not suitable pure metal standards. In the beam current of 10-30 nA range, the Cs x-ray intensity measured from CsBr and CsI was proportional to the beam current. It was found that the linear regression factor R, showing the linearity between the atomic number and x-ray intensity between In and Nd elements, was higher than 0.99 at 25 kV and PET crystal. The caJlculated x-ray intensity of Xe standard from this linear regression equation was 1.095 times higher than that ofTe at 25 kV.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.313-321
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• 2000

This paper deals with a kind of the half-space interfacial problem in time domain, requiring the calculation of the horizontal electric field generated by a tiny impulsive current source located horizontally at the interface between an isotropic upper half-space and a uniaxially anisotropic lower half-space. With the Cagniard-de-Hoop method adapted for our interfacial case, we obtain the explicit-form solution for this electric field. We also investigate the impulse radiation in the radial direction. The impulse components of Dirac $\delta$-function type in transient waveforms are important for the understanding of the interfacial far-field characteristics. The uniaxial case is a generalization of the isotropic one, and the explicit solutions of the uniaxial problem in this paper reduce to the solutions of the isotropic problem if the anisotropy is removed.