• Structural Engineering and Mechanics
• /
• 제64권1호
• /
• pp.93-107
• /
• 2017

The article presents the vibration and acoustic responses of un-baffled doubly curved laminated composite panel structure under the excitation of a harmonic point load. The structural responses are obtained using a simulation model via ANSYS including the effect various geometries (cylindrical, elliptical, spherical and hyperboloid). Initially, the model has been established by solving adequate number of available examples to show the convergence and comparison behaviour of the natural frequencies. Further, the acoustic responses are obtained using an indirect boundary element approach for the coupled fluid-structure analysis in LMS Virtual.lab by importing the natural frequency values. Subsequently, the values for the sound power level are computed using the present numerical model and compared with that of the available published results and in-house experimentally obtained data. Further, the acoustic responses (mean-square velocity, radiation efficiency and sound power level) of the doubly curved layered structures are evaluated using the current simulation model via several numerical experimentations for different structural parameters and corresponding discussions are provided in detail.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제13권6호
• /
• pp.589-593
• /
• 2013

An efficient measurement methodology is proposed to construct the scattering parameters of a multi-port device using a four-port vector network analyzer (VNA) without the external un-terminated ports. By using the four-port VNA, the reflected waves from the un-terminated ports could be minimized. The proposed method significantly enhances the accuracy of the S-parameters with less number of measurements compared to the results of classical renormalization technique which uses two-port VNA. The proposed method is validated from the measured data with the coupled 8-port micro-strip lines.

• 한국생물물리학회:학술대회논문집
• /
• 한국생물물리학회 2003년도 정기총회 및 학술발표회
• /
• pp.27-27
• /
• 2003

Conformations of the +5 to +13 charge state of ubiquitin ions have been studied in the gas phase by an Electron Capture Dissociation (ECD) mass spectrometry (MS) technique. This approach has showed that the conformations of the gaseous ions change from the compact to extended structures as the number of protons on the protein ions increases, consistent with previous collisional cross-section measurements by an ion-mobility MS. However, this observation is in contrast to that of the solution-phase where the unique native structure is usually found. The (un)folding stability and kinetics of these gaseous ions were further investigated experimentally using gradual blackbody-radiation or sudden laser-induced thermal heating, respectively. These studies have provided the evidence that the thermodynamics and kinetics of protein (un)folding in the gas phase are quite different from those of the native aqueous proteins.

• 한국콘텐츠학회논문지
• /
• 제3권2호
• /
• pp.73-77
• /
• 2003

번호이동성(Number Portability)은 이용자의 편익증진과 경쟁활성화를 위한 통신정책의 한 대안으로, 우리나라도 시내전화 및 착신과금서비스는 2003년 상반기부터 비지능망방식인 RCF로, 2G 이동전화의 경우는 2004년부터 지능망방식인 QoR로 시행할 예정이다. 번호이동성을 구현하기 위해서 통신사업자들은 기존의 통신망에 상당부분을 수정하여야 하고 네트워크 특성에 적합한 방식으로 구현하는 것이 중요하다. 본 논문에서는 우리나라에 도입되는 기술구현방식의 장단점을 비교하교 이미 번호이동성을 도입한 외국의 사례를 살펴봄으로써 번호이동성 구현을 위한 합리적인 기술선택방안을 도출하고자 한다.

• 한국해양공학회지
• /
• 제17권2호
• /
• pp.47-53
• /
• 2003

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require such expensive tools, as well as a great deal of time and effort. Therefore, the improvement of fatigue life through, the adoption of residual stress, is the main focus. The compressive residual stress was imposed on the surface according to each shot velocity(1800, 2200, 2600, 3000rpm) based on Shot-peening, which is the method of improving fatigue life and strength. By using the methose mentioned above, we arrived at the following conclusions; 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. In stage I, $\Delta$K$_{th}$, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts, unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. Compressive residual stress of the surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• 한국해양공학회지
• /
• 제18권5호
• /
• pp.43-49
• /
• 2004

The lightness of components required in the automobile and machine industry necessitates the use of high strength components. In particular, the fatigue failure phenomena, which occurs when using metal, increases the danger to human life and property. Therefore, antifatigue failure technology is an integral part of current industries. Currently, the shot peening is used for removing the defect from the surface of steel, while improving the fatigue strength on surface. Therefore, in this paper, the effect of compressive residual stress of spring steel(JISG SUP-9) by shot-peening on fatigue crack growth characteristics in a stress ratio(R=0.1, R=0.3, R=0.6) was investigated, giving consideration to fracture mechanics. By using the methods mentioned above, following conclusions are drawn: (1) The fatigue crack growth rate(da/dN) of the shot-peening material was lower than that of the un-peening material and in stage I, ΔKth, the threshold stress intensity factor of the shot-peen processed material is high in critical parts, unlike the un-peening material. Also m, fatigue crack growth exponent and number of cycle of the shot-peening material, was higher than that of the un-peening material, as concluded from effect of da/dN. (2) Fatigue life shows more improvement in the shot-peening material than in the un-peening material, and the compressive residual stress of surface on the shot-peen processed operate resistance of fatigue crack propagation.

• 한국항만경제학회지
• /
• 제35권3호
• /
• pp.73-92
• /
• 2019

전 세계적으로 재난과 위기 상황이 확산되고 있으며 중국의 쓰촨성 지진과 동일본 대지진과 같이 동북아시아 지역에서도 재난도 증가하는 추세이다. 본 연구는 유엔 세계식량계획 산하의 인도적 물류센터(UNHRD)를 동북아시아의 한국 유치를 제안하는 목적이다. 관련 선행 연구가 국내에는 없지만, 유엔 시설 유치에 대한 국가의 무형적인 이익, 가치와 물류 관련 경제적 효과를 중심으로 연구하며, 유치 효과는 우리나라 기업들의 다양한 인도적 지원 물류 산업 분야로의 진출과 유엔 관련 비즈니스 확대로 예상된다. 유엔조달연감과 대한민국 해외 긴급구호 자료들을 활용하여 관련 유엔기구의 현황을 우선 분석하고 한국의 유치 환경에 대한 SWOT 분석을 통하여 세부 유치 전략을 도출하고자 한다. 한국의 유엔 물류센터 유치 방안으로서는 인도적 지원 관련 국내외 NGO 전문가 협력체계 구축과 홍보, 정부 부처와 지자체 공동 유치 제안, 지속적인 정보 수집과 한국 유치에 관한 타당성 논리개발 등 장기적인 관점에서 유엔의 해당 기관과 긴밀하게 협력하여 전략적으로 추진하는 것이 필요하다.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2003년도 춘계학술대회 논문집
• /
• pp.313-318
• /
• 2003

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress(in this thesis). The compressive residual stress was imposed on the surface according to each shot velocity(57, 70, 83, 96 m/sec) based on Shot-peening, which is the method of improving fatigue lift: and strength. By using the methods mentioned above, I arrived at the following conclusions 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. And in stage I, ${\Delta}K_{th}$, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• Journal of applied mathematics & informatics
• /
• 제31권1_2호
• /
• pp.179-188
• /
• 2013

In this paper, we study the number of solutions to the equation $(x+1)^d=x^d+1$. This equation gives the value of the third power sum equation in case of Niho type exponents and is helpful in finding the distribution of the values $C_d({\tau})$. We provide the number of the solutions using the new method.

• 대한가정학회지
• /
• 제42권9호
• /
• pp.195-212
• /
• 2004

The purpose of this study was to analyze consumers' perceived risk and information search behaviors in internet shopping. For this purpose, survey was conducted on 302 consumers in their 20s and 30s who had internet shopping experience. This study found that consumers' perceived risk was significantly related to their gender, educational level, income, credit card use, period of internet un, number of internet shopping experiences, and purchased product. Consumers' search behaviors were also significantly affected by gender, age, educational level, income, period of internet use, and purchased product. In addition, a higher level of consumers' perceived risk was significantly related to the amount of information search on product attributes themselves rather than on general information search such as the number of sites or the number of brands.