• 한국가시화정보학회지
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• 제21권2호
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• pp.55-62
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• 2023

The characteristic of jet impinging on the concave surface were analyzed through thermographic phosphor thermometry (TPT) and numerical investigation. Under a jet Reynolds number of 6600, nozzle diameters and nozzle-to-surface distances (H/d) were changed 5mm and 10mm and H/d=2 and 5. The RNG k-ε turbulence model can accurately predict the distribution of Nusselt number, compared to other models (SST k-ω, realizable k-ε). Heat transfer characteristics varied with the nozzle diameter and H/d, with a secondary peak noted at H/d =2, due to vortex-induced flow detachment and reattachment. An increase in nozzle diameter enhanced jet momentum, turbulence strength, and heat transfer.

• 한국표면공학회지
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• 제41권6호
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• pp.312-324
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• 2008

In this study, the functional property as a super abrasive material was secured for CBN powder by the electroless Ni-P plating on the surface of the particle. The plating solution has been prepared to control the surface morphology by regulating surfactants and process conditions. The effects of processing parameters on the surface morphology of CBN powder was discussed. The results are summarized as follows; A stable plating tendency was achieved from 1 hour after quantitatively dropping reducing agent. It was observed that more than 50% of the weight gain was obtained by Ni-P coating on the surface of CBN super abrasive powder. The morphology of the Ni-P coating layer is consisted of botryoidal and spiky type and it could be controlled by regulating processing parameters. Superior characteristic in terms of surface morphology was found in the nonionic surfactant XL-80N. It was found that XL-80N considerably decreased surface tension of CBN powder and Ni-P alloy surface then enhance wettability as well as plating rate. Metal coated CBN powder as a raw material of resin bond wheel has been developed through this investigation.

• 열처리공학회지
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• 제22권6호
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• pp.368-374
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• 2009

Nickel titanium shape memory alloys (NiTi) have been investigated for applications in the biomedical industry. However, little is known about the influences of surface modifications on the propertise of these alloys. The effect of electropolishing and heat treatments was found to exhibit significant surface roughness. Change of phase was B2, r-phase and B19' by heat treatments. In this study, effect of the electropolishing conditions on surface roughness is investigated in Ni-Ti alloys (Nitinol). Variation in phases with heat treatment temperature is investigated for a Ni-Ti alloy by X-ray diffraction and DSC. Characteristic of the microstructure have been observed by SEM. Surface roughness have been measured by AFM. The results clearly show that significant different in surface property to heat treated at $500^{\circ}C$ (R-phase). $TiO_2$ phases preciritated all of the specimens. It is not good effect of surface roughness because made to surface relief. The surface roughness appears to be important in the property of Ni-Ti alloys for biomedical applications.

• 한국재료학회지
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• 제32권2호
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• pp.107-113
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• 2022

Fibrous supercapacitors (FSs), owing to their high power density, good safety characteristic, and high flexibility, have recently been in the spotlight as energy storage devices for wearable electronics. However, despite these advantages, FCs face many challenges related to their active material of carbon fiber (CF). CF has low surface area and poor wettability between electrode and electrolyte, which result in low capacitance and poor long-term stability at high current densities. To overcome these limits, fibrous supercapacitors made using surface-activated CF (FS-SACF) are here suggested; these materials have improved specific surface area and better wettability, obtained by introducing porous structure and oxygen-containing functional groups on the CF surface, respectively, through surface engineering. The FS-SACF shows an improved ion diffusion coefficient and better electrochemical performance, including high specific capacity of 223.6 mF cm^-2 at current density of 10 ㎂ cm^-2, high-rate performance of 171.2 mF cm^-2 at current density of 50.0 ㎂ cm^-2, and remarkable, ultrafast cycling stability (96.2 % after 1,000 cycles at current density of 250.0 ㎂ cm^-2). The excellent electrochemical performance is definitely due to the effects of surface functionalization on CF, leading to improved specific surface area and superior ion diffusion capability.

• 한국결정성장학회지
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• 제27권4호
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• pp.212-219
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• 2017

앞으로 다가올 감성이 지배하는 '하이터치(High-Touch)'의 시대에 걸맞은 사람이 되기 위해서는 6가지 능력이 중시되는데 디자인, 스토리, 조화, 공감, 놀이, 의미가 있으며 이 중에서 디자인과의 조화를 가장 중요한 능력으로 꼽았다. 모든 비즈니스의 기본요소라고 볼 수 있는 디자인은 논리적이고 객관화된 정보와 지식을 바탕으로 만들어진 현대의 디자인 관으로는 직관적이고 감성적인 앞으로의 시대 흐름에 발맞추기 힘들 것이다. 본 논문은 1차적 관점의 디자인 소재 중요성과 함께 심도 있는 Color, Material, Finishing(CMF) 이해와 차별화 전략을 세워 소비자가 느끼는 감성인지요소와 제품의 표면처리디자인 적용을 통한 대품질, 매력품질, 감동품질을 만족시키는 감성 표면처리디자인의 체계화 및 표준화를 제시하였다. 제품에 적용되어지는 부품 유형별 CMF 차별화 전략 방향 설정에 따라 구현가능성 차별성 신표면처리특성 효율성을 고려하여 시각적 표면처리 샘플로 구현하였다. 이를 통해 향후 실질적으로 제품 개발 시 IT 및 전자제품 분야와 그 이상의 분야에서 디자이너, CMF 디자이너, 표면처리전문가, 엔지니어 등 실무 환경에서의 대상제품, 부품유형, 적용소재, 적용표면처리, 표면컬러, 표면질감, 구현하고자하는 느낌 등 통합적 요소들을 이해하고 공유할 수 있는 실무자 소통연계 툴 및 감성 표면처리디자인 전략적 접근 프레임워크로서의 활용이 예상되는 바이다.

• 한국CDE학회논문집
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• 제20권3호
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• pp.230-237
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• 2015

Soil deformation on the off-load ground is significantly affected by soil conditions, such as soil type, water content, and etc. Thus, the soil characteristics should be estimated for predicting vehicle movements on the off-load conditions. The plate-sinkage test, a widely-used experimental test for predicting the wheel-soil interaction, provides the soil characteristic parameters from the relationship between soil stress and plate sinkage. In this study, soil stress under the plate-sinkage situation is calculated by the DEM (Discrete Element Method) model. We developed a virtual soil bin with DEM to obtain the vertical reaction forces under the plate pressing the soil surface. Also parametric studies to investigate effects of DEM model parameters, such as, particle density, Young's modulus, dynamic friction, rolling friction, and adhesion, on the characteristic soil parameters were performed.

• 한국세라믹학회지
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• 제41권8호
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• pp.588-592
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• 2004

Dynamic Milling (DM) 방법에 의한 $UO_2$ 분말의 특성 변화가 밀도에 미치는 영향을 조사하였다 분쇄시간(0∼8시간)의 증가에 따라 분말입자의 크기는 감소하며 둥근 형태를 지녔으며, 비표면적과 O/U 비는 증가하였다. 이러한 특성 변화에 의해 성형밀도는 증가한 반면에, 소결밀도는 감소하는 경향을 보였다. 소결밀도의 감소는 분말 분쇄과정에서 야기된 $UO_2$ 분말의 O/U 비의 증가가 주된 영향을 미친 것으로 사료된다.

• 한국실내디자인학회논문집
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• 제13권4호
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• pp.83-91
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• 2004

This study focuses on defining the new meaning of immateriality in the present times expressed on space. The purposes of this study were to examine the characteristics of immateriality showed in commercial interior design in Korea, based on the definition of immateriality concept and the analysis of the way it is expressed. The result of this study is as follows; it categorized characteristic of material expression, space concept and media. Characteristic elements can be classified into 6: transparency, implication, off-gravitation, ambiguity of boundary, temporality, interactivity. Expression of immateriality in commercial interior space was obtained in many different ways, which are identified: new expression of material by reduction of materiality, leveling of transparency, expression of floating status, changeable image, illusion effect, blurring boundary. Immateriality is deeply associated with the elements such as surface, material, media, light, and movement. So it is being recognized as an important design concept in today's pluralist society and will play an important role within the design paradigms for the future.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.2203-2204
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• 2006

When the coil with alternating current approaches to the conductor the eddy current flows in conductor. Eddy current is concentrated on the conductor surface and decrescent because of skin effet.. In this paper investigated eddy current characteristic that is happened in conductor. Analyzed characteristic using electromagnetic field finite element analysis program that is commercialized to analyze value of eddy current and penetration depth. Analyzed creation value of eddy current and penetration depth in conductor that change operation frequency and the material of conductor, coil outside diameter, inside diameter, position, type of conductor from analyzed eddy current characteristic. The results. using distribution of eddy current and penetration depth data is that will help to forecast ECT(Eddy Current Testing), Eddy current application and use field, eddy current loss.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.571-572
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• 2006

When the coil with alternating current approaches to the conductor the eddy current flows in conductor. Eddy current is concentrated on the conductor surface and decrescent because of skin effet.. In this paper investigated eddy current characteristic that is happened in conductor. Analyzed characteristic using electromagnetic field finite element analysis program that is commercialized to analyze value of eddy current and penetration depth. Analyzed creation value of eddy current and penetration depth in conductor that change operation frequency and the material of conductor, coil outside diameter, inside diameter, position, type of conductor from analyzed eddy current characteristic. The results, using distribution of eddy current and penetration depth data is that will help to forecast ECT(Eddy Current Testing), Eddy current application and use field, eddy current loss.