• 열처리공학회지
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• 제17권3호
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• pp.139-145
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• 2004

Equal channel angular pressing (ECAP) technique had been adapted to the Mg alloy (AZ31) for achieving effective grain refinement through severe deformation. The average grain size of $2.5{\mu}m$ could be obtained after 4 passes. The stability of the ECAPed structure at elevated temperatures was examined by annealing the ECAPed materials over a wide range of temperature between 473 and 748 K. The average activation energy, Q, for static grain growth of 1, 2 and 3 passes was 33.7 kJ/mole (=0.25QL, activation for lattice diffusion). The abnormally low Q value in the lower temperature range may indicate that grain growth occurs in the unrecrystallized microstructure where non-equilibrium grain boundaries containing a large number of extrinsic dislocations exist. The yield stresses of the ECAPed alloys decreased whereas the elongations increased after the ECAP process. These results should be related to the modification of texture for easier slip on basal plane.

• 한국조리학회지
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• 제23권7호
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• pp.71-79
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• 2017

This paper presented analysis on the perception by Korean restaurant employees of Korean royal cuisine. Classification using a subjective research method called Q methodology was performed on perceptions of Korean restaurant employees about Korean royal cuisine. This paper derived four types of perceptions. First type (pursuit of tradition) emphasized traditions of royal cuisine, i.e. cooking method and spacious menu-setting on the table. The second type (pursuit of refinement) stressed the importance of "atmosphere and luxuriousness of Korean restaurants and sophistication of royal cuisine, as well as the improvement of interior and exterior environments of Korean restaurants serving royal cuisine. The third type (pursuit of fundamentals) focused on fundamentals of royal cuisine itself such as raw materials, sincere effort, historical meaning, appropriate prices, etc. The last type (pursuit of health) valued a nutritionally balanced diet rather than taste itself. This study provides more specific positioning strategy based on the characteristics of each of the four classifications for the status of Korean restaurants.

• 한국산업정보학회논문지
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• 제13권5호
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• pp.44-54
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• 2008

본 연구의 목적은 인터넷 상거래에서 서비스실패가 발생할 때 기업이 기울이는 서비스회복 활동의 품질 측정도구를 개발하는 것이다. 같은 용도로 Parasuraman 등(2005)이 개발한 E-RecS-QUAL 측정도구를 수정 보완한 본 측정도구는 eSR-Q(electronic Service Recovery Quality)라 명명되었다. 본 측정도구의 신뢰성과 타당성을 검증하기 위해 내적 일관성과 수렴 판별 법칙 타당성 등 구조 타당성의 측면이 집중적으로 분석되었다. 그 결과 4개 차원(반응, 보상, 접촉, 사과) 14개 항목으로 구성된 eSR-Q가 완성되었다. 본 연구는 이 측정도구의 등장배경과 개발 및 검증 과정, 한계점, 그리고 향후 개선방안 등을 다룬다.

• 복식
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• 제63권4호
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• pp.118-131
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• 2013

The purpose of this study is to take a look at the fashion frame of Korean women in their twenties and thirties to sort the actual fashion image and the ideal fashion image according to the fashion frame of Korean women in their twenties and thirties, and also to find out the standards and features that divide such a classification. For this study, we used the Q method, which is valued as an effective way to assess subjectivity. This helps to objectively classify the perception the fashion images of and the response to them as well. The analyzed materials were divided into two actual fashion frames and two ideal fashion frames, and classified them into 12 fashion image types in total, that is, six actual fashion images and six ideal fashion images, and we named each type of the fashion images and analyzed the features of each fashion image type through the in-depth Q workshop in which 14 professionals participated. The results of this study are as follows: First, the actual fashion frames of Korean women in their twenties and thirties was largely divided into 'Fashion Gold Girl', the fashion frame of mainstream and 'Indi-idol', the fashion frame of subcultures, and this was further divided into six fashion image types: 'Basic Casual', 'Vintage Performer', 'Easy Chic', 'Ladies' Look', 'City Office Girl' and 'Club Mania'. Second, the ideal fashion frame of Korean women in their twenties and thirties was divided into 'Urban Refinement', the fashion frame of the mainstream and 'Mismatched Style', the fashion frame of subcultures. It was also divided into six fashion image types: Power Fashion', 'Fashion Conservative', 'Semi-culture', 'Fashion Otaku', 'Sweet Darling' and 'Fashion Panic'. Third, The characteristics of the fashion images' colors are recognizable according to the type of fashion images.

• 복합신소재구조학회 논문집
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• 제4권1호
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• pp.1-8
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• 2013

The finite element analysis (FEA) is a numerical technique to find solutions of field problems. A field problem is approximated by differential equations or integral expressions. In a finite element, the field quantity is allowed to have a simple spatial variation in terms of linear or polynomial functions. This paper represents a review and an accuracy-study of the finite element method comparing the FEA results with the exact solution. The exact solutions were calculated by solid mechanics and FEA using matrix stiffness method. For this study, simple bar and cantilever models were considered to evaluate four types of basic elements - constant strain triangle (CST), linear strain triangle (LST), bi-linear-rectangle(Q4),and quadratic-rectangle(Q8). The bar model was subjected to uniaxial loading whereas in case of the cantilever model moment loading was used. In the uniaxial loading case, all basic element results of the displacement and stress in x-direction agreed well with the exact solutions. In the moment loading case, the displacement in y-direction using LST and Q8 elements were acceptable compared to the exact solution, but CST and Q4 elements had to be improved by the mesh refinement.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권9호
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• pp.611-615
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• 1999

Piezoelectric properties of PMN-PZT ceramics with $CeO_2$ impurity were investigated. Mechanical quality factor, $Q_m$ of 1792, 1285 and the electromechanical coupling coefficient, $k_p$ of 0.52, 0.54 were obtained from the specimen with 0.25 and 0.5 mole % $CeO_2$ respectively. Curie temperature was decreased with the addition of $CeO_2$ while the electric coercive field was proportional to the amount of impurity. Based on the system ceramics with 0.5 mole % cerium oxide, a Rosen type piezoelectric transformer was fabricated and tested. Voltage step-up ratios of 230 and 13 were obtained from the transformer at no load and $100 k\Omega$ resistance, respectively. Experimental results showed a potential of the transformer for the practical use coupled with the expected strength increase by the grain size refinement.

• 소성∙가공
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• 제4권2호
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• pp.159-168
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• 1995

The torsion tests in the range of $550~800^{\circ}C$, $5.0{\times}10^{-3}~5.0{\times}10^0/sec$ were performed to study the effects of strain rate$(\.{\varepsilon})$ and temperature(T) on the hot strength of Cu-Zn alloy. High temperature flow stresses of this alloy increased with increasing $\.{\varepsilon}$ and/or decreasing T, and than the more grain refinement could be obtained. The flow curves exhibited a peak followed by a steady steady state regime as a result of dynamic recrystallization. The hot strength dependence of $\.{\varepsilon}$ and T was described by a hyperbolic sine law, $\.{\varepsilon}=A(sinh0.017{\sigma})^4.81$exp(-216KJ/mol). Hot strength could be reduced at the arbitary condition, $\.{\varepsilon}$ and T, by constitutive parameter Z(Zenner-Hollomon parameter), $Z=A(sinh{\alpha}{\sigma})^n=\.{\varepsilon}$exp(Q/RT).

• 한국자동차공학회논문집
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• 제20권3호
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• pp.1-6
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• 2012

This paper developed the chassis part as micro-alloyed steel with high toughness. The performance of micro-alloy steels are superior to similar heat treated steels. The strengthening effects of vanadium make micro-alloyed steels particularly suited for high-strength-steel applications. The disadvantages are that ductility and toughness are not as good as quenched and tempered (Q&T) steels. Precipitation hardening increases strength but may contribute to brittleness. Toughness can be improved by reducing carbon content and titanium additions. dispersed titanium nitrides (TiN) formed by titanium additions effectively prevents grain coarsening. Grain refinement increases strength but also improves toughness. For the chassis parts using high toughness micro-alloy steel, it had proven superior to a plain steel forging by static strength test and endurance test.

• 전산구조공학
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• 제10권1호
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• pp.185-191
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• 1997

보 및 아치형 구조물은 2차원 탄성체이지만 두께가 상대적으로 매우 얇다는 특성 때문에 Kirchhoff이나 Reissner-Mindlin이론과 같이 변위장의 두께방향 변위를 선형함수로 근사화시켜왔다. 그 결과 2차원 문제가 물체의 중립면에서 표현되는 1차원 문제로 차원이 감소되어 이론적 해석이 간편해 진다. 그러나 경계에서와 같이 두께방향 변위가 복잡한 영역의 거동을 보다 정확히 해석하기 위해서는 2차원 선형 탄성이론이나 두께방향 다항식의 차수가 상당히 높아야 한다. 본 논문은 두께방향 다항식의 차수변화에 따른 해석정도 경향 및 여러 다른 차수를 한 문제 영역에 혼합하는 모델조합에 대한 내용을 제시한다.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1679-1683
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• 2018

Polycrystalline $BaSrCo_2(Fe_{1-x}Al_x)_{12}O_{22}$ (x = 0.00, 0.01, 0.05, and 0.10) samples were synthesized by polymerizable complex method. Based on the Rietveld refinement, crystal structures of the samples were found to be single-phased and determined to be rhombohedral with space group of R-3m. The hysteresis curves of the samples were measured under 15 kOe at various temperatures ranging from 4.2 and 295 K. It shows that they were not saturated with increasing Al ion contents due to the reduction of magnetic anisotropy. $M_{15kOe}$ was decreased with increasing Al ions contents. We expect that non-magnetic Al ions preferentially occupy the up-spin site of $18h_{VI}$, $3b_{VI}$, and $3a_{VI}$. The $M{\ddot{o}}ssbauer$ spectra of the samples were obtained at 295 K, and analyzed with sixsextets for Fe sites corresponding to the Y-type hexaferrite crystallography sites. The <$E_Q$> shows abrupt changes, and the <$H_{hf}$> shows abrupt decreases around x = 0.05 due to the coexistence of magnetic secondary phases.