• 한국표면공학회지
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• 제31권2호
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• pp.91-100
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• 1998

NiCrAlY/YSZ(8wt%$Y_2O_3-ZrO_2$) functionally graded thermal barrier coating (FGC) layers on a Co-base superalloy (HAYNESS 188) substrate were fabstrate were fabicated using Ar shielded single torch air plasma spraying method. Functional grading with the stepwise compositional change throughout layer thickness. Microstructural observation trvealed a successful fabrication of NiCrAlY/YSZ FGC. From the results of the curvature measurement, adhesive strength measurement and thermal shock test for the FGC, it was concluded that the optimum conditions of functionally graded coating layer thinkness and compositional pattern exit to enhance the properties of FGC, which is closely related to the internal residual stess distribution witin it.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.76-76
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• 2010

Using ab initio density functional calculations, we investigate the structural and electronic properties of porous schwarzite structures formed by $sp^2$ carbon minimal surfaces with negative Gaussian curvature. We calculate the equilibrium geometries, elastic properties and electronic structure of two systems with cubic unit cells containing 152 and 200 carbon atoms, which are metallic and very rigid. The porous schwarzite structure can be efficiently doped by electron donors as well as accepors, making it a promising candidate for the next generation of alkali ion batteries. Furthermore, the schwarzite structures can be magnetic when doped and thus act as arrays of interconnected quantum spin dots. We also propose that two interpenetrating schwarzite structures be used as a ultimate super-capacitor.

• 대한수학회보
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• 제59권2호
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• pp.407-417
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• 2022

Archimedes proved that for a point P on a parabola X and a chord AB of X parallel to the tangent of X at P, the area of the region bounded by the parabola X and the chord AB is four thirds of the area of the triangle ∆ABP. This property was proved to be a characteristic of parabolas, so called the Archimedean characterization of parabolas. In this article, we study strictly convex curves in the plane ℝ². As a result, first using a functional equation we establish a characterization theorem for quadrics. With the help of this characterization we give another proof of the Archimedean characterization of parabolas. Finally, we present two related conditions which are necessary and sufficient for a strictly convex curve in the plane to be an open arc of a parabola.

• 한국의류산업학회지
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• 제17권5호
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• pp.781-792
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• 2015

This study aims to develop a spring/fall motorcycle jacket for quick service transporter. Depending on the results of the previous research, this study produced the tested jacket which was improved in material, pattern, and design. For the tested jacket, 100% polyester fabric excellent in strength, durability and abrasion-resistance was selected as a major material, and Cordura was used as a partial material to improve the strength and abrasion-resistance of the sleeve side lines, elbow and shoulder areas. The retro-reflection material was applied partially in order to improve visibility of the jacket in the night or in a dark place. A total of 7 pockets were composed in the jacket for the sufficient storage spaces. The functional design elements such as the 2-way zipper and the placket at the center front, the action pleats at the upper part of back armholes, the pit-zip at armpit were applied. In addition, the sleeve pattern was bent with the shape of elbow curvature in time of driving and the back length of the jacket was lengthened 4cm. As a result of the appearance assessment, there was a significant difference from the existing jacket in all items but chest size, shoulder width, cuffs circumference, and jacket hemline circumference. In motion adaptability and field activity appropriateness assessments, the assessment grade for all items was found to be commonly higher than that of the existing jacket, and thus, the tested jacket was assessed to be suitable for a motorcycle jacket design for the quick service transporters.

• 대한토목학회논문집
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• 제11권1호
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• pp.117-124
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• 1991

운동량방정식을 이용한 하천만곡부 외측제방에 작용하는 단위면적당 수류력은 흐름의 특성, 토사의 특성 및 만곡부의 기하학적 인자의 함수인 곡률계수로 표현할 수 있다. 일반적으로 곡률비가 2.0~4.1인 경우에 외측제방에 작용하는 수류력이 가장크게 나타나는데 한강하류부의 경우 곡률비가 2.0~4.0에 집중된 것은 전구간에서 제방침식을 받게될 가능성이 높을 것으로 사료되어 하천개수계획수립시 필수적으로 고려되어야 하며 철저한 호안공 등의 방법으로 보완되어야 할 것이다. 한편 곡률계수가 최대인 곡률비의 범위가 1963년의 경우 2.21~4.42이고 1981년에는 1.93~3.54이며, 인위적인 하천개 보수공사를 고려한 년간 평균유로이동률이 1967년까지 4.68m/yr이고 1981년까지는 10.48m/yr이다.

• 대한전자공학회논문지SP
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• 제44권4호통권316호
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• pp.86-92
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• 2007

2D 영상의 특징점을 추적하는 이산동적 모델을 고안한다. 종래의 스네이크 접근은 내외 추진력으로 구성된 에너지함수를 최소화하도록 구획을 변형시켜가면서 영상 내의 원하는 특징에 밀착시켜간다. 이 때 스네이크화소를 중심한 인접화소군은 사각형 같은 평면 2차 행렬이다. 본 논문에서는 유사 특성점들을 상호 연결하는 모델 구조를 제시한다. 에너지모델은 그 국부최소점이 활성처리에 유용한 교차 해법에 적합하도록 설계한다. 추적시 선 형태의 1차 행렬 블록을 사용한다. 진행 방향의 반대 끝 라인으로부터 굴곡상태를 만족하는 시발점들을 선정하고 에너지 최소처리를 통해 이웃 라인으로 순차 자동 이동한다. 추적 경로는 상승 하강점 또는 극대 극소점과 같은 굴곡 한계에 의존한다. 이와 같은 층위적 접근은 인접데이터 라인 사이에 수직 또는 수평 방향으로 높은 상관성을 갖는 일방향 특성이 있는 디지털 영상의 특징점 추적에 유용하다. 그리고 인체 경동맥초음파영상에서 그 내 외막 시점을 추적하는 실험으로 알고리즘의 효과를 확인하였다.

• Archives of Plastic Surgery
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• 제37권3호
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• pp.250-255
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• 2010

Purpose: Pincer nail is a relatively rare deformity characterized by an increase in transverse curvature along the longitudinal axis of the nail. This curvature commonly increases from proximal to distal end of nail, leading to pinching, curling, and distortion of the underlying soft tissue and resulting frequently in severe pain. Numerous surgical procedures have been reported. Preserving the width of the nail in the correction of the pincer nail is very important for functional and aesthetic reasons. We report the results of the correction of the pincer nail using autogenous dermofat graft with a good result. Methods: From May 2006 to September 2008, dermofat graft was performed in 6 patients with pincer nail. Patients were four women and two men, and the average age was 51. The affected digits were the unilateral great toes in four patients and the unilateral thumbs in two patients. Average follow-up period was 13 months. Surgical procedure was removal of nail using an elevator to avoid damage to the nail bed. An incision was created in distal portion of hyponychium. Paronychium was dissected from distal phalanx by periosteal elevator through incision of hyponychium and tunnel was made. Then dermofat grafts harvested from inguinal area were inserted into the tunnel. Finally, a silicone sheet was inserted eponychial fold for prevention of synechia. Objective assessment was evaluated by use of the width index and height index. Results: All patients reported resolution of the pain and soft tissue pinching sensation that they had before the operation. There was good adherence between the nail plate and the underlying nail bed. The nails have regrown and were corrected in a normal and flattened appearance. The width index and height index were improved. Conclusion: The autogenous dermofat graft seems to provide an effective treatment of the pincer nail with preservation of the nail matrix.

• 한국멀티미디어학회논문지
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• 제17권3호
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• pp.393-404
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• 2014

본 연구는 전통건축 방식의 지붕곡을 전산학적으로 재해석하고 지붕가구부를 구성하는 부재들간의 기하학적 상관관계를 3D 데이터로 설계하기 위한 방안을 제시한다. 지붕곡을 형성하는 여러 개의 구성 요소, 즉 지붕가구부 부재들간의 상관관계를 전통건축 축조 방식에 근거하여 함수식으로 정의하고 분석된 데이터를 토대로 사용자가 원하는 지붕면을 구성하기 위한 각 부재들의 3차원 데이터 자동 생성 기법을 구현한다. 제안하는 방식은 부재간의 상관관계를 고려하여 지붕곡의 속성이 변경되면 지붕곡에 영향을 미치는 여러 개의 부재들이 자동으로 재설계되는 방식으로써 전통건축 설계의 효율을 높일 수 있다. 또한, 한옥의 다양한 지붕곡 설계를 보장하면서도 체계적인 설계와 규격화된 생산 및 가공을 가능하게 하여 한옥의 보급에 크게 기여할 수 있을 것으로 기대된다.

• 한국유체기계학회 논문집
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• 제7권2호
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• pp.7-13
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• 2004

In an attempt to solve multiobjective optimization problems, weighted sum method is most widely used for the advantage that a designer can consider the relative significance of each object functions by weight values but it can be highly sensitive to weight vector and occasionally yield a deviated optimum from the relative weighting values designer designated because the multiobjective function has the form of simple sum of the product of the weighting values and the object functions in traditional approach. To search the design solution agree well to the designer's weighting values, we proposed new multiobjective function which was the functional of each normalized objective functions and considered to find the design solution comparing the distance between the characteristic line and the ideal optimum. In this study, proposed multiobjective function was applied to design high efficiency and low noise axial flow fan and the result shows this approach is effective for the case that the quality of the design can be highly affected by the designer's subjectiveness represented as weighting values in multiobjective design optimization process.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1187-1194
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• 2011

The hydrogen abstraction reaction of $CF_3CH_2CHO$ + OH has been studied theoretically by dual-level direct dynamics method. Two stable conformers, trans- and cis-$CF_3CH_2CHO$, have been located, and there are four distinct OH hydrogen-abstraction channels from t-$CF_3CH_2CHO$ and two channels from c-$CF_3CH_2CHO$. The required potential energy surface information for the kinetic calculation was obtained at the MCG3-MPWB//M06-2X/aug-cc-pVDZ level. The rate constants, which were calculated using improved canonical transitionstate theory with small-curvature tunneling correction (ICVT/SCT) were fitted by a four-parameter Arrhenius equation. It is shown that the reaction proceeds predominantly via the H-abstraction from the -CHO group over the temperature range 200-2000 K. The calculated rate constants were in good agreement with the experimental data between 263 and 358 K.