• Korean Journal of Materials Research
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• v.12 no.7
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• pp.568-572
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• 2002

Plasma sulfnitriding technology was employed to harden the surface of SKD61 steel. The plasma sulfnitriding was performed with 3 torr gas pressure at $580^{\circ}C$ for 20 hours. Plasma sulfnitriding resulted in the formation of very thin $2-3\mu\textrm{m}$ FeS sulfide layer on top of $15-20\mu\textrm{m}$ compound layer, which consisted of predominantly $\varepsilon$- $Fe{2-3}$ N and a second phase of $\Upsilon'-Fe_4$N. In comparision with plasma nitriding treatment, plasma sulfnitriding treatment showed better surface roughness and corrosion resistance due to the presence of the thin FeS layer. which coated microvoids and microcracks on top of the nitrided layer. It was also found that plasma sulfnitrided sample showed better wear resistance due to the presence of the thin FeS layer which acted as a solid lubricant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.849-852
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• 2002

Recently, amorphous selenium is used as x-ray conversion material for flat-panel x-ray detector. In this paper, we investigated the effect of breakdown under high voltage and leakage current in PN-type multi-layer structure based on p-type a-Se and n-type conductive thin film. Experimental results show that the multi-layer based detector reduced leakage current because n-type CeO2 conductive layer prevent from hole injection into a-Se layer from collection electrode, Also, the breakdown voltage was improved by dielectric layer between a-Se and top electrode.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.1075-1076
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• 2012

인터넷의 발달로 데이터가 이질적이고 방대해점에 따라 사용자의 의도와 목적에 맞는 정보를 빠르고 정확하게 찾아내는 것이 어려워지고, 대용량의 데이터를 빠르게 검색 할 수 있는 효율적인 top k 질의 처리가 중요해 지고 있다. top k 질의 처리는 릴레이션에서 가장 높은 (또는 가장 낮은) 값을 가지는 k개의 튜플을 반환하는 방법이며, 그 중 Layer 기반 방법은 객체가 가지는 d개의 속성 값들을 d-차원의 공간상의 점 객체로 랩핑하여, layer들의 list를 생성 한다. 본 논문에서는 Layer 기반 법 중 skyline을 사용하여 layer을 생성하고 인덱스를 구축하는 기존 연구에 대해서 조사한다. 그리고 대표적인 방법인 모든 객체를 순차적으로 비교하는 BNL과 이의 비교 횟수를 감소시킨 SFS, 그리고 R-tree를 사용한 NN과 이의 계산 비용을 감소시킨 BBS에 대해 설명한다.

• Strategy21
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• s.42
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• pp.196-223
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• 2017

The aim of this paper is to analyze China's naval strengthening and threat reflected in submarines, aircraft, destroyers and missile capabilities and US Navy's counter-forces. China is strengthening its naval forces in accordance with its three-step naval force build-up plan, and the introduction of Russian destroyers and submarines is a foothold for China's naval enforcement. The Chinese Navy also converted the concept of the First-Second Island Chain Defense, which it had already maintained, to the concept of maritime layer defense. Currently, the Chinese Navy maintains the concept of a Three-Maritime Layer Defense which includes the South China Sea, where artificial islands are being built by China, in the First Layer Defense and the East China Sea in the Third Layer Defense. Along with the advancement of Chinese Navy's submarines, surface vessels and aircraft's operational capabilities, ballistic and cruise missile capabilities become a major threat to the US Navy. If a crisis occurs in the East China Sea or in the Taiwan Waters, the US Navy will face more difficulties in employing the Carrier Strike Group to manage the crisis. Meanwhile, if a crisis occurs on the Korean Peninsula, it will be a burden to dispatch Carrier Strike GroupS to the East and West Seas of the Korean Peninsula. For the stable future, the US Navy should develop a strategy to respond more effectively to the Chinese Navy, which is challenging new maritime supremacy in East Asia.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.1001-1010
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• 2001

In TLM method, Discrete Green's function ABC have been used when improved the exactness of analyzing in wide frequency band. But this technology has a complicated process to apply absorbing boundary, which means it needs additional numerical analyzing process to obtain discrete Green's function data. so, In this paper, we propose new Green's absorbing layer for simple process to apply absorbing boundary. newly proposed Green's absorbing layer is produced by applying of loss operation, loading discrete Green's function with attenuation. A state of optimum absorbing would be obtained by relation between increasing rate of loss, attenuation constant and length of green's absorbing layer. and then Analysts of waveguide BPF is carried out using Green's absorbing layer within state of optimum absorbing, then this result is in corrective agreement with the result applying traditional discrete Green's function ABC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.112-113
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• 2006

In this paper. we investigated a characteristic of holographic grating data erasure with non-polarized beam at amorphous chalcogenide As-Ge-Se-S thin film. A sample of holographic grating data was formed with DPSS laser for setup. Then, the erasure process was performed with He-Ne laser vertically at sample. As-Ge-Se-S(single layer). Ag/As-Ge-Se-S(double layer) and As-Ge-Se-S/Ag/As-Ge-Se-S(multi-layer) are manufactured to compare their characteristic of erasure.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.169-173
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• 2008

The objective of this study is to coat the $SiO_2$ layer uniformly on the ZnS:Cu phosphors by using Sol-Gel method. From results of SEM micrographs observation, XRD and XPS analysis, it could be confirmed that $SiO_2$ layer was relatively well coated on ZnS:Cu particles. $Ag_2S$ was used as a decoding chemical to analyze the dense and uniform coating performance of $SiO_2$ layer on phosphor particles. It could be concluded that phosphors synthesized from our two step replacement method showed strong blue peak comparing to other method and rather weak green peak also. Obtained particle size of phosphors were about 20m diameter. Luminescence properties of the phosphors were examined by photoluminescence spectra at the excitation wavelength of 270 nm.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.64-65
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• 2002

Recently the synthetic antiferromagnetic layer (SAF) has received much attention because it replaces the pinned layer of the conventional spin valve (CSV) sensors and its overall performance [1], The spin valve (SV) with SAF has the from buffer/F/Cu/APl/Ru/AP2/AF, where F is the soft ferromagnetic layer (typically NiFe with CoFe interfacial doping), AP1 and AP2 are two ferromagnetic layers (typically CoFe alloys) antiferromagnetically coupled through a thin Ru layer. (omitted)

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.43-50
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• 2019

In this research, the effect of bedding layer on the tensile failure mechanism of rocks has been investigated using PFC2D. For this purpose, firstly calibration of PFC2d was performed using Brazilian tensile strength. Secondly Brazilian test was performed on the bedding layer. Thickness of layers were 5 mm, 10 mm and 20 mm. in each thickness layer, layer angles changes from $0^{\circ}$ to $90^{\circ}$ with increment of $15^{\circ}$. Totally, 21 model were simulated and tested by loading rate of 0.016 mm/s. The results show that when layer angle is less than 15, tensile cracks initiates between the layers and propagate till coalesce with model boundary. Its trace is too high. With increasing the layer angle, less layer mobilizes in failure process. Also, the failure trace is very short. It's to be noted that number of cracks decrease with increasing the layer thickness. Also, Brazilian tensile strength is minimum when bedding layer angle is between $45^{\circ}$ and $75^{\circ}$. The maximum one is related to layer angle of $90^{\circ}$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.277-280
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• 2008

Multi layer bellows are being manufactured for commercial vehicle because of the characteristic of high durability compared with single iaγor bellows used to passenger vehicle. Finite Element Method (FEM) study and optimization about single layer bellows are actively progressed, but FEM study about multi layer bellows which have gap between layer is rarely processed. Therefore, this article presents finite element modeling of multi layer bellows for the improvement of simulation reliability. For the shape optimization of multi layer bellows, design of experiment and Taguchi method are used.