• The Journal of the Acoustical Society of Korea
• /
• v.10 no.2
• /
• pp.36-43
• /
• 1991

Acoustic backscattering from a buble column in water was studied theoretically and experimentally. For theoretical analysis a general scattering theory was used by assuming the bubble column to be lumped element scatterer which can be characterized by its shape, void fraction and dimensions. When the void fraction is less than 1% and the incident frequency is higher than individual bubble resonance frequencies, the experimental results show that the acoustic backscattering from a bubble column depends mainly on the void fraction rather than the individual bubble sizes. It was also theoretically and experimentally observed that the acoustic backscattering levels were increased and their peaks moved to the lower frequency regin by raising the void fraction of bubble column.

• Journal of KIISE:Computer Systems and Theory
• /
• v.27 no.9
• /
• pp.777-784
• /
• 2000

최근 물리적으로 분산 메모리 하드웨어 상에서 공유메모리 프로그래밍 모델을 제공하는 3소프트웨어 분산 공유 메모리(Distributed Shared Memory, DSM) 시스템을 위해 여러 프로토콜이 등장하고 있다. 본 논문에서는 기존의 동적 복원 프로토콜인 하이브리드 프로토콜[11]의 성능향상을 제안하는 두 가지 문제를 밝혀내고 이를 개선하기 위한 향상된 하이브리드 프로토콜을 제안한다. 이 프로토콜은 동기화 시점에서 기존 프로토콜과 같이 과거에 어떤 페이지를 이미 접근한 프로세스에 대해서 복원 프로토콜을 적용할 뿐만 아니라. 그 페이지에 접근한 프로세스의 수가 선택된 파라미터 값 이상이면 모든 프로세스에 대해 복원 프로토콜을 적용한다. 제안한 프로토콜을 DSM 시스템인 CVM에 구현하고 100Mbps인 Ethernet으로 연결된 8대의 Sun ultral상에서 6개의 응용 프로그램에 대해 성능평가를 수행하였다. 그결과 원격 프로세스에 대한 수정정보 요구 메시지의 수를 평균 16% 감소시켰고, 4개의 응용프로그램에서 2-5%의 성능향상을 얻었다.

• The Research Journal of the Costume Culture
• /
• v.4 no.3
• /
• pp.395-406
• /
• 1996

This article aims, by analyzing structurally the codification of dress sign in Korean society, the signifying system of the codes and their message communicated, to make clear a signifying structure that would be codified through the relationship between abstract concepts and real condition of dress. I used the semiotic theory of Ferdinand de Saussure′s conception on structuralismly the codification, cultural semiology of Roland Barthes and Myung-Sook Han′s formula of dress structure as tools analyse may objective of wedding dress of folks in Choson Dynasty, which has been successive our traditional Korean wedding dress. My results of the study are : The procedure of wedding ceremony in Choson Dynasty was presented in texts like Juga-garye, Sarye-peonram and Kukjo-orye, its dress system has been more emphasized on language, and aspect of social system, than parole, one of individual realization. In addition, the meanings of marrage such as "Oneness of bride and bridegroom", "Mixture of two sexes", "Blessing of good luck", were included in the signified like the style, pattern and color of the wedding dress, and specially, pattern and color, the articulated morphemes, was emphasized, When we combinated terms of dress in Choson Dynasty with syntagmatic, regarding their list as paradigmatic, it will signify a wedding dress, and according to combinating ways, it amy be divided as sign of dresses of bride and bridgeroom by sex or king, gentry and common people by class. Wedding Dress in Choson Dynasty = [{ODx(U/Dxu/d)}+AC·H·FW].

• Journal of Ocean Engineering and Technology
• /
• v.31 no.5
• /
• pp.371-377
• /
• 2017

This paper introduces a simulation-based determination method for hydrodynamic derivatives and 6DOF (degrees-offreedom) motion analysis for an underwater vehicle. Hydrodynamic derivatives were derived from second-order modulus expansion and composed of the added mass, and linear and nonlinear damping coefficients. The added mass coefficients were analytically obtained using the potential theory. All of the linear and nonlinear damping coefficients were determined using CFD simulation, which were performed for various cases based on the actual operating condition. Then, the linear and nonlinear damping coefficients were determined by fitting the CFD results, which referred to 6DOF forces and moments acting on an underwater vehicle, with the least square method. To demonstrate the applicability of the current study, 6DOF simulations for three different scenarios (L-, U-, and S-turn) were carried out, and the results were validated on the basis of physical plausibility.

• Child Health Nursing Research
• /
• v.26 no.3
• /
• pp.357-365
• /
• 2020

Purpose: The aim of this study was to investigate internet addiction among middle school students and to examine the mediating effects of social support in the relationships of self-efficacy and self-control with internet addiction. Methods: The participants in the study were 119 middle school students in J city. The measurements included a self-efficacy scale, a self-control scale, a social support scale, and the Internet Addiction Scale for Youth. Data were analyzed using the independent t-test or Mann-Whitney U test, one-way analysis of variance, the Scheffé test, Pearson correlation coefficients, and multiple-regression using SPSS version 22.0. Mediation effects were analyzed by the Sobel test and Baron and Kenny's hierarchical analysis technique. Results: Significant correlations were found among self-efficacy, self-control, and internet addiction. Social support had partial mediating effects in the relationship between self-efficacy and internet addiction, as well as in the relationship between self-control and internet addition. Conclusion: In order to prevent internet addiction, the promotion of interactions among peers, which is a component of social support, is particularly important. It is also necessary to promote face-to-face activities that can strengthen relationships. The findings suggest that intensifying social support may help reduce the level of internet addiction in middle school students.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.30 no.9_10 s.157
• /
• pp.1413-1422
• /
• 2006

Technologies such as television shopping channels and the internet expand consumers' impulse purchasing opportunities. The interest in national differences of consumer behavior was growing and highlighted the importance of understanding the national context of consumer behavior in an increasing globalized marketplace. The purposes of this study were to examine the effects of fashion involvement and hedonic consumption on impulse buying for Korean and American young consumers, and to compare the differences between two groups. A questionnaire was developed from literatures reviewed. Data were obtained from students attending universities in Korea(N=413) and the U.S.(N=290). Using structural equation modeling, the results indicated that the proposed model of this study was appropriate to explain the effects of fashion involvement and hedonic consumption on impulse buying for Korean and American young consumers. The model showed that fashion involvement and hedonic consumption played important roles in triggering impulse buying for two groups. In addition, American consumers were more likely to influence fashion involvement and hedonic consumption on impulse buying than Korean consumers. The results provided some insights into globalized retail marketing theory supporting the national aspects of impulse buying. Future research and managerial implications are addressed.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 1998.10a
• /
• pp.613-622
• /
• 1998

This study investigates the factors that affect the adoption of object orientation . One major research question is addressed : What are the factors that significantly influeence the adoption of object orientation ? This study especially explores the impact of independent variables on the level of actual usage of object orientation. The independent variables are classified into four categories as follow ; (1) Individual factors : amount of experience in using the structures methods and level of openness toward new technologies ; (2) Managerical factors : perceived management support and training : (3) Organizatinal factors : number of IS professionals in the working group and that in organization ; and (4) Environmental factors ; accessibility to technology champions and software hardware environment supporting object orientation. A Questionnaire measuring the above variables was utilized to investigate the effect of these variables on the dependent variable, the actual usage of object orientation. The structured questionnaire was administered to Data Processing Management Association (DPMA) professionals in U. S. The results of this study revealed several important findings with most results being consistent with expectations based on related theory. The personal openness toward new technologies, perceived management support, training, and hardware/software environment were highly related to the usage of object orientation. This study suggested an empiriclal basis for understanding the early adoption of object orientation in organization.

• Journal of KIISE:Computer Systems and Theory
• /
• v.26 no.3
• /
• pp.313-323
• /
• 1999

현재 컴퓨터 시장에서는 버스에 기반한 시스템이 주류를 이루고 있다. 프로세서의 속도가 매우 빠른 속도로 증가하고 있기 때문에 버스는 병목현상을 일으키고 , 버스의 속도는 불완전한 전송선의 한계로 인해서 제한된다. 시스템 연구자들은 버스를 고속의 단방향 지점간 링크(point-to-point link)를 사용해서 대체하려고 하고 있다. 이 논문에서 새로운 링 구조의 시스템(PANDA)을 제안하고,이 시스템에 적합한 스누핑 캐쉬 일관성 프로토콜을 제사한다. 또한 제안된 시스템은 SCI 캐쉬 일관성 프로토콜을 채택하는 시스템의 네트워크 인터페이스를 수정함으로써 쉽게 구현될 수 있는 이점을 지닌다. 확률적 모델링과 program-driven simulator를 이용하여 제안된 시스템과 full map 디렉토리 프로토콜을 사용하는 시스템과 스누핑 프로토콜을 사용하는 슬롯 링 시스템(Express Ring)을 분석하였다. 실험의 결과로 제안된 시스템은 부가적 하드웨어가 필요한 full map 디렉토리 시스템에 비해서 대등한 성능을 지니고 슬롯링 시스템에 비해서는 29%까지의 성능향상을 보인다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.12 s.243
• /
• pp.1586-1596
• /
• 2005

In this paper, a structural damage identification method (SDIM) is developed to identify the line crack-like directional damages generated within a cylindrical shell. First, the equations of motion for a damaged cylindrical shell are derived. Based on a theory of continuum damage mechanics, a small material volume containing a directional damage is represented by the effective orthotropic elastic stiffness, which is dependent of the size and the orientation of the damage with respect to the global coordinates. The present SDIM is then derived from the frequency response function (FRF) directly solved from the equations of motion of a damaged shell. In contrast with most existing SDIMs which require the modal parameters measured in both intact and damaged states, the present SDIM may require only the FRF-data measured at damaged state. By virtue of utilizing FRF-data, one may choose as many sets of excitation frequency and FRF measurement point as needed to acquire a sufficient number of equations for damage identification analysis. The numerically simulated damage identification tests are conducted to study the feasibility of the present SDIM.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.585-588
• /
• 2005

Many process parameters have an effect on the auto-body panel forming process. A well designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented, in this paper The one-step approach using a finite element inverse method will be introduced to predict the optimal forming with changing of blank pressure the developed program is applied to auto-body panel forming.