• Journal of Mechanical Science and Technology
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• v.18 no.1
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• pp.106-113
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• 2004

Recently, a new issue in designing spot welded structures such as automobile and train car bodies is to predict an economical fatigue design criterion. One of the most typical and traditional methods is to use a ΔP-N$\sub$f/ curve. However, since the fatigue data on the ΔP-N$\sub$f/ curve vary according to the welding conditions, materials, geometry of joint and fatigue loading conditions, it is necessary to perform the additional fatigue tests for determining a new fatigue design criterion of spot-welded lap joint having specific dimension and geometry. In this study, the stress distributions around spot welds of various spot welded lap joints such as in-plane bending type (IB type), tension shea. type (TS type) and cross tension type (CT type) were numerically analyzed. Using these results, the ΔP-N$\sub$f/ curves Previously obtained from the fatigue tests for each type were rearranged into the Δ$\sigma$-N$\sub$f/ relations with the maximum stresses at the nugget edge of the spot weld.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.1
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• pp.30-34
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• 2016

In this paper, we report that selective etching on N-polar face by EC (electro-chemical)-etching effect on the reduction of bowing and strain of FS (free-standing)-GaN substrates. We applied the EC-etching to concave and convex type of FS-GaN substrates. After the EC-etching for FS-GaN, nano porous structure was formed on N-polar face of concave and convex type of FS-GaN. Consequently, the bowing in the convex type of FS-GaN substrate was decreased but the bowing in the concave type of FS-GaN substrate was increased. Furthermore, the FWHM (full width at half maximum) of (1 0 2) reflection for the convex type of FS-GaN was significantly decreased from 601 to 259 arcsec. In the case, we confirmed that the EC-etching method was very effective to reduce the bowing in the convex type of FS-GaN and the compressive stress in N-polar face of convex type of FS-GaN was fully released by Raman measurement.

• Journal of the Korean Applied Science and Technology
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• v.15 no.1
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• pp.63-78
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• 1998

A series of long chain N-acyl amino acid type anionic surfactants were prepared by treating fatty acid chlorides with three kinds of amino acids, that is, sodium N-acyl-sarcosinates, sodium N-acyl-N-methyl-${\beta}$-alaninates and sodium N-acyl-N-methyl-taurates in an alkaline solution. All prepared biodegradable surfactants were purified by thin layer chromatography and column chromatography, and identified their structures by spectral analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.319-320
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• 2009

In this study, high-quality Al-N doped p-type ZnO thin films were deposited on n-type Si (100) wafer or Si coated with buffer layer by DC magnetron sputtering in the mixture of $N_2$ and $O_2$ gas. The target was ceramic ZnO mixed with $Al_2O_3$ (2 wt%). The p-type ZnO thin film showed higher carrier concentration $2.93\times10^{17}cm^{-3}$, lower resistivity of $5.349\;{\Omega}cm$ and mobility of $3.99\;cm^2V^{-1}S^{-1}$, respectively. According to PL spectrum, the Al donor energy level depth ($E_d$) of Al-N codoped p-type ZnO film was reduced to about 51 meV, and the N acceptor energy level depth ($E_a$) was reduced to 63 meV, respectively.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.675-678
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• 2003

본 논문에서는 N-type 기판에서 Nickel-Silicide를 적용하였을 경우에 나타나는 문제점과 PAI (Pre-amorphization Implant)의 효과에 대하여 알아보았다. N-type 기판에 RTP (Rapid Thermal Process)를 통하여 Nickel-Silicide 를 형성하게 되는데, 여기까지는 안정한 Nickel mono-Silicide (NiSi)가 형성됨을 확인하였다. 하지만 후속 열처리 공정 후 심한 응집 현상 (Agglomeration)과 이상 산화 현상 (Abnormal Oxidation Phenomenon), Silicide Island 등 열안정성 (Thermal Stability) 측면에서 여러 가지 많은 문제점들이 나타났다. 이 후속 열처리의 열안정성 취약점들을 극복하는 방안으로 Ge 및 N₂ PAI를 적용하였다. PAI를 적용하였을 경우에는 그렇지 않은 경우에 비하여 고온 열처리 후에도 면저항이 비교적 잘 유지되었으며, 두께가 얇고 안정한 Nickel-Silicide 특성을 확보할 수 있었다. 특히 Ge PAI 에 비하여 N₂ PAI 의 경우가 보다 특성 개선 효과가 크게 나타났다.

• Bulletin of the Korean Mathematical Society
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• v.20 no.1
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• pp.45-49
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• 1983

If R is ring and M is a right (or left) R-module, then M is called a faithful R-module if, for some a in R, x.a=0 for all x.mem.M then a=0. In [4], R.E. Johnson defines that M is a prime module if every non-zero submodule of M is faithful. Let us define that M is of prime type provided that M is faithful if and only if every non-zero submodule is faithful. We call a right (left) ideal I of R is of prime type if R/I is of prime type as a R-module. This is equivalent to the condition that if xRy.subeq.I then either x.mem.I ro y.mem.I (see [5:3:1]). It is easy to see that in case R is a commutative ring then a right or left ideal of a prime type is just a prime ideal. We have defined in [5], that a chain of right ideals of prime type in a ring R is a finite strictly increasing sequence I$_{0}$.contnd.I$_{1}$.contnd....contnd.I$_{n}$; the length of the chain is n. By the right dimension of a ring R, which is denoted by dim, R, we mean the supremum of the length of all chains of right ideals of prime type in R. It is an integer .geq.0 or .inf.. The left dimension of R, which is denoted by dim$_{l}$ R is similarly defined. It was shown in [5], that dim$_{r}$R=0 if and only if dim$_{l}$ R=0 if and only if R modulo the prime radical is a strongly regular ring. By "a strongly regular ring", we mean that for every a in R there is x in R such that axa=a=a$^{2}$x. It was also shown that R is a simple ring if and only if every right ideal is of prime type if and only if every left ideal is of prime type. In case, R is a (right or left) primitive ring then dim$_{r}$R=n if and only if dim$_{l}$ R=n if and only if R.iden.D$_{n+1}$ , n+1 by n+1 matrix ring on a division ring D. in this paper, we establish the following results: (1) If R is prime ring and dim$_{r}$R=n then either R is a righe Ore domain such that every non-zero right ideal of a prime type contains a non-zero minimal prime ideal or the classical ring of ritght quotients is isomorphic to m*m matrix ring over a division ring where m.leq.n+1. (b) If R is prime ring and dim$_{r}$R=n then dim$_{l}$ R=n if dim$_{l}$ R=n if dim$_{l}$ R<.inf. (c) Let R be a principal right and left ideal domain. If dim$_{r}$R=1 then R is an unique factorization domain.TEX>R=1 then R is an unique factorization domain.

• The Journal of the Korea Contents Association
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• v.19 no.11
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• pp.92-101
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• 2019

This study used the Q-method to derive the structure of subjective opinions and perceptions of university students about the behavior of food delivery agency service provided by staff not directly employed in restaurants. For this purpose, the Q factor analysis was performed using the PC QUANL program for the Q-sort, which consists of a statement card, a P-sample, and a classification process. The results were classified into three types. The factor names were set as the first type (N = 7): efficiency seeking type, the second type (N = 19): benefit seeking type, and the third type [(N = 6): cost-effectiveness seeking type. The characteristics of each type are Type 1:Types that recognize aspects that are efficient for both consumers and restaurants, Type 2: Types of recognizing aspects of being benefited from speed, convenience and benefit, Type 3: Although it contributes to labor cost savings, it appears to recognize price and quality aspects in the initial market, which is burdened by consumers. The purpose of this study is to derive the problems of food delivery agency service business according to the three types and to provide strategic implications for the development direction and improvement plan.

• East Asian mathematical journal
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• v.34 no.5
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• pp.643-649
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• 2018

Let M be a connected n-dimensional submanifold of a Euclidean space $E^{n+k}$ equipped with the induced metric and ${\Delta}$ its Laplacian. If the position vector x of M is decomposed as a sum of three vectors $x=x_1+x_2+x_0$ where two vectors $x_1$ and $x_2$ are non-constant eigenvectors of the Laplacian, i.e., ${\Delta}x_i={\lambda}_ix_i$, i = 1, 2 (${\lambda}_i{\in}R$) and $x_0$ is a constant vector, then, M is called a 2-type submanifold. In this paper we proved that a connected 2-type hypersurface M in $E^{n+1}$ whose postion vector x satisfies ${\langle}{\Delta}x,x-x_0{\rangle}=c$ for a constant c, where ${\langle}$, ${\rangle}$ is the usual inner product in $E^{n+1}$, is of null 2-type and has constant mean curvature and scalar curvature.

• Communications of the Korean Mathematical Society
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• v.36 no.3
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• pp.465-483
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• 2021

Let 𝓗(𝔻) be the space of analytic functions on the unit disc 𝔻. Let 𝜓 = (𝜓_j)ⁿ_j=0 and 𝚽 = (𝚽_j)ⁿ_j=0 be such that 𝜓_j, 𝚽_j ∈ 𝓗(𝔻). The linear differential operator is defined by T_𝜓(f) = ∑ⁿ_j=0 𝜓_jf^(j), f ∈ 𝓗(𝔻). We characterize the boundedness and compactness of the difference operator (T_𝜓 - T_𝚽)(f) = ∑ⁿ_j=0 (𝜓_j - 𝚽_j) f^(j) between weighted-type spaces of analytic functions. As applications, we obtained boundedness and compactness of the difference of multiplication operators between weighted-type and Bloch-type spaces. Also, we give examples of unbounded (non compact) differential operators such that their difference is bounded (compact).

• The Journal of the Korea Contents Association
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• v.20 no.5
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• pp.128-139
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• 2020

This study is a recognition type study on the usefulness of the field-practice program conducted by departments related to eating out and cooking. The purpose of this study is to derive the common types found among students who have experienced on-the-job training in special cases where the completion of on-the-job training programs, such as the Department of Culinary Arts and Engineering, are designated as graduation requirements and major required courses. By analyzing, we will explore and analyze the factors and issues that can affect the program participation process. As a result of recognition type analysis, a total of four types were derived, and each type was named according to its specificity as follows. Type 1 (N = 8): Sense of Purpose Setting type, Type 2 (N = 8): Interaction Skill Acquisition Types, Type 3 (N = 6): Major Practice Education Enlargement Type, Type 4 (N = 6): The Field Adaptability Improvement Type was analyzed for each unique feature type. Based on the results, it is suggested that efforts to systematize the field practice regulations, improve the government's field practice system plans, and discover new industries to provide opportunities for cultivating practical skills by supplementing the problems of the field practice regulations.