• 한국지반신소재학회논문집
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• 제17권2호
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• pp.1-7
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• 2018

해안지대나 습지와 같은 연약지반에 도로나 철도 건설이 빈번해지면서 이를 위한 연약지반 개량 사례가 증가하고 있다. 일반적으로 연약지반 개량시 작업조건만을 고려하거나 경제성만을 고려한 공법은 다수 존재하나 작업조건과 경제성을 함께 고려할 경우 적용 가능한 공법은 제한적이다. 이러한 경우 표층부와 심층부를 병용하여 개량하는 공법이 적용되어지는데, 이에 대한 기초적인 연구가 부족한 현실이다. 따라서, 본 연구에서는 연약지반에서 표층부 개량과 심층부 개량을 병용하는 경우에 대해 모형시험을 수행하여 지오그리드 보강 효과를 확인하고자 하였으며, 이때 표층부의 두께, 심층부 개량체의 직경 및 길이가 지오그리드 보강 효과에 미치는 영향을 파악하고자 하였다. 그 결과 표층부의 두께가 심층부의 직경보다 보강효과가 크다는 것을 확인하였고, 또한 표층부를 지오그리드로 보강한 경우 표층부의 강도가 증진되어 침하량이 저감됨을 확인하였다.

• 한국해양공학회지
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• 제18권4호
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• pp.46-51
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• 2004

The surface layer in dredged and reclaimed marine clay is improved by mixing of shallow soils and hardening agents, which is made of cement, containing some other special admixtures. Tests in both laboratory and field settings are performed to investigate the improvement effect and strength properties of cement-stabilized soils. The test results show that the hardening agent sufficiently improves the soil properties of the surface layer, while increasing the load-carrying capacity. The strength of cement-stabilized soils depends, primarily, on water-to-cement ratio and curing temperature. That is, the higher curing temperature and the longer curing time, the higher the strength in cement-stabilized soils. The high ratio of water-ta-cement results in a lower strength.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.777-778
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• 2006

This paper deals with the optimum rotor design approach about the multi-layer design of the buried magnets in an Interior Permanent Magnet Synchronous Motor (IPMSM), on the efficiency improvement by using Response Surface Methodology (RSM). In the multi-layer design of the prototype 15kw IPMSM, the constant amount of buried PM is split from the single-layer into double-layer design for improving the efficiency characteristics. The optimum double-layer rotor structure is built with the help of RSM analysis. The improvement of IPMSM efficiency is verified by the Finite Element Method (FEM) results comparison with the prototype single-layer IPMSM.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.959-963
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• 1996

Hardened layer and compressive residual stress created by carburized treatment effect on bending fatigue strength of gear massively. Also, shot peening treatment improves the strength of carburized gear as it does the hardness and residual stress of surface layer. In these days shot peening techniques are welcomed as one of physical improvement ways around the surface of materials. It is used widely because qualitative analysis of shot peening has become possible and surface treatment can be done with very little costs compared to other surface improvement methods. Therefore this study investigates the effect of shot peening in surface shape and bending fatigue strength after doing many kinds of shot peening treatments, then doing fatigue test and also explained characteristics of shot peening gear.

• 한국정밀공학회지
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• 제14권9호
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• pp.61-67
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• 1997

Hardened layer and compressive residual stress created by carburized treatment effect on bending strength of gear massively. Also, shot peening treatment improves the strength of carburized gear as it does the hardness and residual stress of surface layer. In these days shot peening techniques are welcomed as one of physical improvement ways around the surface of materials. It is used widely because qualitative analysis of shot peening has become possible and surface treatment can be done with very little costs comparaed to other surface improvement methods. Therefore this study investigates the effect of shot peening in surface shape and bending fatigue strength after doing many kinds of shot peening treatments, then doing fatigue test and also explained characteristics of shot peening gear.

• 한국표면공학회지
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• 제48권1호
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• pp.1-6
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• 2015

Amino-carboxyl acid as a complexing agent in acid copper sulfate solution was utilized to improve the adhesion of immersion copper layer for steel wire. According to the tape test results, regardless of alloy composition of the wire, the adhesion of immersion copper layer was improved with the addition of amino-carboxyl acid. The incorporation of H and Fe in the plating layer was analyzed by TOF-SIMS. The H and Fe were detected at the entire coating layer without any addition of amino-carboxyl acid. However, with addition of amino-carboxyl acid, the H and Fe were scarcely detected at the coating layer.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.731-738
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• 2002

Recently, as large constructions on the coast are performed frequently, surface layer stabilization method which Is one of the improvement methods for dredged soft clay has been applied. However, there have been few studies about the surface layer stabilization method. The purpose of this study is to clarify characteristics of ultra-soft marine clay and hardening agent. Also, optimal mixture ratio of hardening agent was verified through the laboratory tests such as statistical analysis and pilot tests. Laboratory tests were performed with proper hardening agent and test soil and standard mixing tables of hardening agent were determined according to ground conditions through statistical analysis. Also, applicability of surface layer stabilization method to field was verified by pilot tests. From the results of the tests, it was found that hardening agent materials such as cement, slag, fly-ash, inorganic salts, arwin, gypsum etc. affect on the appearing compressive strength. It was defined optimal mixture ratio which satisfies the required compressive strength from the statistical analysis. Also, It was compared the effect of ground improvement by cements and hardening agents through the pilot tests. This study will serve as data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.

• Journal of Welding and Joining
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• 제15권5호
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• pp.134-143
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• 1997

The formation of thick alloyed layer with high Si content have been investigated on the surface of Al alloy (A5083) plate by PTA process with Si powder. Hardening characteristics and wear resistance of alloyed layer was examined in relation to the microstructure of alloyed layer. Thick hardened layer in mm-order thickness on the surface of A5083 plate can be formed by PTA process with wide range of process condition by using Si powder as alloying element because of eutectic reaction of Al-Si binary alloy. High temperature and rapid solidification rate of molten pool, which are features of PTA process, enable the formation of high Si content alloyed layer with uniform distribution of fine primary Si paticle. High plasma arc current was beneficial to make the alloyed layer with smooth surface appearance in wide range of powder feeding rate, because enough volume of molten pool was necessary make alloyed layer. Uniform dispersion of fine primary Si particle with about 30${\mu}{\textrm}{m}$ in particle size can be obtained in layer with Si content ranging from 30 to 50 mass %. Hardness of alloyed layer increased with increasing Si content, but increasing rate of hardness differed with macrostructure of alloyed layer. Wear resistance of alloyed layer depended on $V_{si}$(volume fraction of primary Si) and was remarkably improved to two times of base metal at 20-30% $V_{si}$ without cracking, but no more improvement was obtained at larger $V_{si}$.

• 폴리머
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• 제36권4호
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• pp.461-469
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• 2012

아르곤(Ar) 플라즈마 처리된 폴리프로필렌 복합소재의 표면 개질 및 특성 변화를 X-선 광전자 분광 분석(XPS), 적외선 분광 분석(FTIR), 주사 전자 현미경 분석(SEM) 및 접촉각 측정 등을 이용하여 조사하였다. Ar 플라즈마 처리 시간의 증가는 폴리프로필렌 복합소재 표면의 젖음성, 극성 관능기를 갖는 산소 성분, 탈크 함량 및 표면조도의 증가를 초래하였다. 주사 전자 현미경 분석을 통한 자세한 관찰은 폴리프로필렌 성분으로 구성된 표면층(skin layer)이 존재함을 확인하였다. 폴리프로필렌과 고무 입자간의 점도차는 표면층의 생성을 촉진시켰다. 하지만 Ar 플라즈마 처리시간의 증가는 표면층의 두께를 감소시키는 것을 확인하였다. 사출성형 공정 동안, 표면층을 제거할 수 있는 추가적인 방법론에 대해서도 토의하였다. Ar 플라즈마 처리에 의한 표면 개질 및 모폴로지의 변화는 폴리프로필렌 복합소재 표면 상에 친수화 상태를 부여하고, 이에 따라 젖음성 향상을 유도하였다.

• 한국표면공학회지
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• 제41권1호
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• pp.1-5
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• 2008

In this work, improvement of mechanical and electrical properties of gate dielectric layer for flexible organic thin film transistor (OTFT) devices was investigated. In order to increase the mechanical flexibility of PVP (poly(4-vinyl phenol) organic gate dielectric, a very thin inorganic $HfO_2$ layers with the thickness of $5{\sim}20nm$ was inserted in between the spin-coated PVP layers. Insertion of the inorganic $HfO_2$ in the laminated organic/inorganic structure of PVP/$HfO_2$/PVP layer led to a dramatic reduction in the leakage current compared to the pure PVP layer. Under repetitive cyclic bending, the leakage current density of the laminated PVP/$HfO_2$/PVP layer with the thickness of 20-nm $HfO_2$ layer was not changed, while that of the single PVP layer was increased significantly. Mechanical flexibility tests of the OTFT devices by cyclic bending with 5 mm bending radius indicated that the leakage current of the laminated PVP/$HfO_2$(20 nm)/PVP gate dielectric in the device structure was also much smaller than that of the single PVP layer.