• Advances in nano research
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• 제12권6호
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• pp.583-592
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• 2022

In this paper, a pulsed picosecond laser dressing method for bronze-bonded diamond wheel is studied systematically and comprehensively. The picosecond laser pulse ablation experiment is carried out, and the ablation thresholds of bronze-bonded and diamond abrasive particle are measured respectively. The results indicate that the single-pulse ablation thresholds of bronze-bonded are 0.89J/cm², 0.24J/cm² during strong/weak ablation stages. And the multi-pulse ablation thresholds of diamond abrasive particle are 1.69J/cm², 0.49J/cm² during strong/weak ablation stages. Obviously, diamond grains have less thermal damage during the process of gentle ablation. The diamond grains of the grinding wheel surface are graphitized during laser dressing. The bronze-bonded is relatively smooth and organizational stability, and the diamond grits have suitable prominent height, which are beneficial to maintain the good grinding performance of dressed bronze-bonded diamond grinding wheels.

• 수산해양기술연구
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• 제30권3호
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• pp.172-181
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• 1994

The mesh selectivity of diamond and suare mesh cod-ends at the Southern Korean Sea and the East China Sea were compared for Pampus argenteus, Trachurus japonicus, Trichiurus lepturus. Selection trials were carried out using diamond and square mesh cod-end by trouser type cod-end with cover net. of which the mesh cod-end has four types : A(51.2mm), B(70.2mm), C(77.6mm), D(88.0mm). Selection curves and selection parameters were calculated using a logistic model. The results obained are summarized as follows : 1. Harvest fish : In B. C and D type selection range and fifty percent selection length of the square mesh were about 21mm, 11mm : 12mm, 18mm and 34mm, 5mm higher than those of the diamond mesh, respectively. Selection factor of master curve for the diamond mesh was 1.54 and for the square mesh was 1.68. The optimum mesh size for the diamond mesh was 97.4mm and for the square mesh was 89.3mm, the difference was 8.1mm. 2. Horse mackerel : In A type, selection range was nearly the same for the diamond and the square mesh, but fifty percent selection length of the square mesh was 43mm higher than the diamond mesh. In B. C and D type, selection range and fifty percent selection length of the square mesh were about 6mm, 3mm : 24mm, 21mm and 11mm, 42mm higher than those of the diamond mesh, respectively. Selection factor of master curve for the diamond mesh was 2.37, for the square mesh was 2.77. The optimum mesh size for the diamond mesh was 78.1mm and for the square mesh was 66.8mm, the difference was 11.3mm. 3. Hair tail : In A, B and C type, selection range of the square mesh was about 34mm, 8mm, 60mm higher than those of the diamond mesh. Fifty percent selection length for the diamond mesh was about 5mm, 7mm, 8mm higher than that of the square mesh. Selection factor of master curve for the diamond mesh was 3.11, for the square mesh was 3.48. The optimum mesh size for the diamond mesh was 64.3mm and for the square mesh was 57.5mm, the difference was 6.8mm.

• 한국전자파학회논문지
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• 제14권5호
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• pp.536-541
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• 2003

본 논문에서는 다이아몬드 표면에의 산소흡착을 억제함으로써 양호한 전기적특성을 가지는 다이아몬드 MISFET를 제작하기 위해 초고진공 프로세스(ultrahigh vacuum process)에 의해 A1/Ca $F_2$/diamond MISFET를 제작하였다. 박막반도체 다이아몬드의 표면도전층으로서는 불소종단에 의해 형성되는 표면 도전층을 이용하였다. 초고진공 프로세스에 의해 제작된 A1/Ca $F_2$/diamond MISFET로부터 상용화된 실리콘 MOSFET와 동등한 레벨인~$10^{11}$ /$cm^2$ eV의 저농도의 표면준위밀도가 관측되었고, 유효이동도 $\mu$ $e_{ff}$ 는 이제까지 발표된 박막반도체 다이아몬드 FET중 최고치인 300 $cm^2$/Vs 이었다. 본 논문에서는 또한 초고진공 프로세스에 의해 제작된 Al/Ca $F_2$/diamond MISFET를 이용하여 인버터회로(inverter circuit)를 제작하였으며, 고온고주파 환경에서 양호한 전기적 특성을 관찰하였다. 본 논문의 특징은 초고진공 프로세스에 의해 제작된 불소화 다이아몬드 박막반도체 MISFET에 관한 최초의 보고이며, 또한 다이아몬드 박막반도체 MISFET의 인버터회로(inverter circuit)동작에 관한 최초의 보고이다.다.

• 한국의류학회지
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• 제30권9_10호
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• pp.1354-1365
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• 2006

China has a big potential as an apparel market due to its rapid economic growth. In the fashion industry, great attention has been paid to China. However, analysis of competitiveness has received relatively little attention from fashion scholarship. This study attempts to apply the double diamond model to analyze the international competitiveness of the apparel industry of China as well as of Korea. The purpose of this study is 1) to establish diamond model components in the fashion industry for Korea and China respectively, and 2) to compare the established diamond models(i.e., double diamond model, multinational diamond model) between Korea and China. Finally we suggested a marketing strategy based on the results of the double diamond model application. To build a diamond model for each country intensive literature review were conducted and additionally quantitative data were collected from 31 merchandisers and managers. We found that the domestic diamond of China was larger than Korea's, but firm strategy, structure and rivalry condition of Korea were more competitive than China's. Secondly, regarding the international diamond, China was more competitive, and especially had more the larger factor condition than Korea confirming that Korea was less competitive than China. This article provides a theoretical background and empirical findings for the competitiveness model of the fashion industry.

• 한국표면공학회지
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• 제53권5호
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• pp.241-248
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• 2020

The change of the deposition behavior of diamond through a pretreatment process of the base metal prior to diamond deposition using HFCVD was investigated. To improve the specific surface area of the base material, sanding was performed using sandblasting first, and chemical etching treatment was performed to further improve the uniform specific surface area. Chemical etching was performed by immersing the base material in HCl solutions with various etching time. Thereafter, seeding was performed by immersing the sanded and etched base material in a diamond seeding solution. Diamond deposition according to all pretreatment conditions was performed under the same conditions. Methane was used as the carbon source and hydrogen was used as the reaction gas. The most optimal conditions were found by analyzing the improvement of the specific surface area and uniformity, and the optimal diamond seeding solution concentration and immersion time were also obtained for the diamond particle seeding method. As a result, the sandblasted base material was immersed in 20% HCl for 60 minutes at 100 ℃ and chemically etched, and then immersed in a diamond seeding solution of 5 g/L and seeded using ultrasonic waves for 30 minutes. It was possible to obtain optimized economical diamond film growth rates.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2002년도 춘계 학술발표강연 및 논문개요집
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• pp.132-132
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• 2002

Diamond is well known as the hardest material in nature. It also has other unique bulk physical and mechanical properties, such as very high thermal conductivity and broad optical transparency, which enable a number of new applications now that large areas of diamond can be fabricated by the new diamond plasma chemical vapor deposition (CVD) technologies. A study on the effects of growth kinetics and properties of diamond films obtained by addition of argon (~7 vol. %) into the methane/hydrogen mixture is carried out using HFCVD system. A negative bias was used as a nucleation enhancement method in addition to the argon dilution. The scanning electron microscopy (SEM) image of surface morphology shows well faceted crystallites with a predominance of angular shapes corresponding to <100> and <110> crystalline surfaces. The nucleation density and growth rate with argon dilution is two orders of magnitude higher than without argon deposition. The Raman spectra show a good quality film whereas XPS spectra show existence of only diamond phase.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.184-187
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• 1996

Diamod nucleation by mw assisted CVD was examined various conditions namely, (1) diamond nucleation on variour substrate materials, such as Si, cubic BN, pyrolytic BN and AIN, (2) AST(Activated species transport) method which promote nucleation of diamond on single crystal and polycrystalline alumina substrate was developed. (3) Effect of bias enhancement of nucleation on single crystalline Si was examined, and finally (4) DST (Double step treatment) method was developed to enhance diamond nucleation on Ni. In this method, we separated carbon diffusing process into Ni, carbon precipitating process from the inside of Ni and diamond precipitation process.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.193-196
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• 1996

A new type of electron emitter device of chemical-vapor-deposited diamond thin film is proposed. The device is a diode of metal-insulator-insulator-semiconductor (MIS) structure consisting of an intrinsic polycrystalline diamond film as the insulator, an aluminium electrode on one side, and hydrogenated diamond surface on the other side as the p-type semconductor with negative electron affinity (NEA). Electrons will be injected and/or excited to the conduction band of intrinsic diamond layer to be emitted from the hydrogenated diamond surface of NEA.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.212-215
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• 1996

This paper focuses the strength and wear resistance of CVD diamond films. The strength of free-standing CVD diamond films synthesized by microwave plasm CVD, DC plasma CVD, RF plasma CVD and arc discharge plasma jet CVD has been measured by three-point bending test. The wear resistance of CVD diamod films has been evaluated by the pin-on-disk type testing. diamond films coated on the base of sintered tungsten carbide pin by hot filament CVD have been rubbed with a sintered diamond disk in muddy water. Volume removed wear of CVD diamond has been compared with stellite, WC alloy and bearing steel.

• The Korean Journal of Ceramics
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• 제3권2호
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• pp.105-109
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• 1997

The effects of surface conditions of the C-2 cemented carbide substrate on the adhesion of diamond film were investigated. The substrates were pretreated for different times with Murakami's reagent and then the acid solution of an H2SO4-H2O2. The adhesion strength was estimated by a peeling area around the Rockwell-A indentation. The cutting performance of the diamond-coated tools was evaluated by measuring flank wears in dry turning of Al-17% Si alloy. The morphology of deposited diamond crystallites was dominated by (111) and (220) surfaces with a cubooctahedral shape. The diamond film quality was hardly affected by the surface conditions of the substrate. The variation of tool life with longer substrate etching times resulted from a compromies between the increase of film adhesion at the interface and the decrease of toughness at the substrate surface. The coated tools were mainly deteriorated by chipping and flaking of the diamond film form a lock of adhesion strength, differently from the wear phenomena of PCD tools.