• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제24권5호
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• pp.413-422
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• 2021

Intestinal lymphangiectasia is a rare disease which is causing protein-losing enteropathy. Treatment of intestinal lymphangiectasia can be a challenge for clinicians because of the lack of specific guidelines regarding pharmacological indications. We sought to introduce a diagnostic approach and suggest guidelines for treatment. After exclusion of secondary intestinal lymphangiectasia, magnetic resonance lymphangiography is a promising tool for the assessment of abnormal lymphatic lesions in primary intestinal lymphangiectasia. Determining the extent of the lesion provides direction for treatment options. Focal short-segment intestinal lymphangiectasia can be treated via intestinal resection or radiologic embolization after dietary therapy failure. Diffuse intestinal lymphangiectasia and extensive lymphangiectasia should be treated with several drugs with a full understanding of their mechanisms.

• Steel and Composite Structures
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• 제20권3호
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• pp.623-649
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• 2016

Most of the early studies on plates vibration are focused on two-dimensional theories, these theories reduce the dimensions of problems from three to two by introducing some assumptions in mathematical modeling leading to simpler expressions and derivation of solutions. However, these simplifications inherently bring errors and therefore may lead to unreliable results for relatively thick plates. The main objective of this research paper is to present 3-D elasticity solution for free vibration analysis of continuously graded carbon nanotube-reinforced (CGCNTR) rectangular plates resting on two-parameter elastic foundations. The volume fractions of oriented, straight single-walled carbon nanotubes (SWCNTs) are assumed to be graded in the thickness direction. In this study, an equivalent continuum model based on the Eshelby-Mori-Tanaka approach is employed to estimate the effective constitutive law of the elastic isotropic medium (matrix) with oriented, straight carbon nanotubes (CNTs). The proposed rectangular plates have two opposite edges simply supported, while all possible combinations of free, simply supported and clamped boundary conditions are applied to the other two edges. The formulations are based on the three-dimensional elasticity theory. A semi-analytical approach composed of differential quadrature method (DQM) and series solution is adopted to solve the equations of motion. The fast rate of convergence of the method is demonstrated and comparison studies are carried out to establish its very high accuracy and versatility. The 2-D differential quadrature method as an efficient and accurate numerical tool is used to discretize the governing equations and to implement the boundary conditions. The convergence of the method is demonstrated and to validate the results, comparisons are made between the present results and results reported by well-known references for special cases treated before, have confirmed accuracy and efficiency of the present approach. The novelty of the present work is to exploit Eshelby-Mori-Tanaka approach in order to reveal the impacts of the volume fractions of oriented CNTs, different CNTs distributions, various coefficients of foundation and different combinations of free, simply supported and clamped boundary conditions on the vibrational characteristics of CGCNTR rectangular plates. The new results can be used as benchmark solutions for future researches.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권4호
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• pp.922-937
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• 2024

Maritime activities are on the rise, there is a growing demand for high-quality communication services that can cover larger areas. However, the transmission of high data rates to maritime users is challenging due to path loss from land base stations, which limits the transmission power. To overcome this challenge, researchers have been exploring the use of buoys in a marine environment as relays for communication technology. This paper proposes a simulation-based approach to investigate the impact of various beamwidths on communication performance when using a buoy as a relay. The objective is to determine the optimal beamwidth that yields the highest data rate for the target location. The approach is based on an offshore wave model where the direction of the buoy changes according to the height of the wave. The study investigates the performance of the relay in the downlink situation using receive beamforming, and the capacity at the user in the three-hop situation is verified using an amplify-and-forward (AF) relay that uses transmit beamforming to the user. The simulation results suggest that the beamwidth of the relay should be adjusted according to the wave conditions to optimize the data rate and relay position that satisfies a data rate superior to the direct path to the target position. Using a buoy as a relay can be a promising solution for enhancing maritime communications, and the simulation-based approach proposed in this paper can provide insights into how to optimize beamwidth for effective communication system design and implementation. In conclusion, the study results suggest that the use of buoys as relays for maritime communication is a feasible solution for expanding coverage and enhancing communication quality. The proposed simulation-based approach provides a useful tool for identifying relay beamwidths for achieving higher data rates in different wave conditions. These findings have significant implications for the design and deployment of communication systems in maritime environments.

• 디자인학연구
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• 제15권4호
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• pp.399-408
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• 2002

오늘날 소비자들은 생활수준의 향상과 더불어 제품 구매시, 그 제품이 가지는 가치 중에서 제품이 '사용자의 이미지를 얼마나 잘 대변해 주고 있는지' 하는 상징적인 이미지가 중요한 구매결정 요소가 되고 있다. 이러한 맥락에서 제품 디자인 개발에 있어서 사용자의 상징적 이미지에 관한 정보가 절대적으로 중요하나, 그 구체적인 사용자의 정성적(Qualitative) 정보를 조사하고 분석하는 방법의 개발은 무척 미약한 편이다. 이러한 점에서 사용자의 자아개념 추출 틀(framework)의 개발을 통한 사용자 이미지 정보의 제공은 디자이너에게 유용한 사용자를 이해 할 수 있는 가이드라인(Guideline)정보로써의 궁극적으로 디자인 방향설정에 도움을 줄 수 있을 것이다. 이러한 목적을 위하여 본 연구에서는 사용자군의 자아개념 추출을 위한 21개 언어적 항목을 개발하여 제시했으며, 본 연구에서 사례조사를 통해 개발된 21개 언어적 사용자 자아개념 이미지 평가척도와 사회과학분석 툴(인구통계학적 data분석과 인자분석, 군집분석)의 보완적 활용방안을 모색해 보았다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1201-1207
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• 2008

Numerical analysis information will be very useful to improve fluid system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas coming to the cylinder of a reciprocating compressor are presented in this paper. Suction-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement, such as reducing the varying flow parameters and flow reorientation should be done. Consequently, development of the better hydrogen compressing system will be achieved.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술논문발표회
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• pp.109-113
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• 2002

Urban public service is goods and activities which satisfy public demands for the political, social, economic, cultural activity and household affairs of individual or groups and which urban government supply with free of charge. In view of government, in addition to fairness of facilities location, location of such facilities are to be determined the respect to cost of locating facilities and developmental direction in the future. Therefore, it is necessary to study on feasibility. A feasibility study Is an effective tool in determining the decision of investment or not and the level of investment priority on Projects requiring a sizeable investment and the feasibility of a project. The first, it is to select reasonable location. It was selected four and two by consideration of facilities distribution and connection with others. Six proposal selected was estimated by five element of approach, demand, symbol, reality, environment. In result proposal I was chosen. The next, it is to estimate scales. The finally, it is to study on economical efficiency. Net Present Value was came out ￦4.4billion by 20years and Inter Rate of Return showed up 11%. in addition, it offer various benefit by public facilities. In conclusion, this project is reasonable.

• 지능정보연구
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• 제7권1호
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• pp.63-79
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• 2001

비모수적인 효율성 분석기법인 자료봉합분석(Data Envelopment Analysis) 은 현재 학교, 은행, 병원 등 여러 분야에서 각 조직의 효율성을 평가하는데 응용되고 있다. 그러나, 방법론 적용에 있어 상대적으로 비효율적인 의사결정단위의 참조집합이 1개 이상의 효율적인 의사결정단위로 구성되어 있어, 어느 방향으로 개선해야 할지 가이드라인을 제공하지 못하고 또한 효율성 크기에 따라, 비효율적인 의사결정단위의 단계적인 개선 방향을 제공하지 못한다는 불편한 점이 있다. 따라서, 본 연구에서는 이와 같은 불편한 점을 보완하기 위한 자료봉합분석과 기계학습을 이용한 하이브리드 방법론을 개발하고, 이를 국내 29개 생명보험사에 적용하여 타당성을 검증하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.695-702
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• 2010

Numerical analysis information will be very useful to improve fluid system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas coming to the cylinder of a reciprocating compressor are presented in this paper. Suction-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement, such as reducing the varying flow parameters and flow reorientation should be done. Consequently, development of the better hydrogen compressing system will be achieved.

• 한국정밀공학회지
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• 제20권7호
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• pp.114-119
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• 2003

The aligning between the punch and die governs no only the burr formation characteristics but also the life time of the punch and die in the sheet metal blanking process. There are many ways to adjust the two elements in the general punching systems but in the case of micro punch system, the punch size is reduced to a few tenth of micrometer range and the general aligning methods are almost impossible to apply. The image processing is the most widely used method in micro punch aligning, but in order to apply the method, it needs quite a large space for visionary system to approach the punch-die aligning zone. In this paper, the new punch-die aligning method with using the total capacitance between the punch and die hole is proposed. In this method, the tip surface of the punch tool locates at the same plane of the die surface and the capacitance variation between the two elements are measured. When the center of the two elements are coincided, the capacitance is minimized, but when the align is changed to any direction, the capacitance between the two elements increase. In order to verify the feasibility of this method, the aligning and punching tests was performed.

• Journal of Computational Design and Engineering
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• 제3권1호
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• pp.63-70
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• 2016

Deep drawing is a forming process in which a blank of sheet metal is radially drawn into a forming die by the mechanical action of a punch and converted to required shape. Deep drawing involves complex material flow conditions and force distributions. Radial drawing stresses and tangential compressive stresses are induced in flange region due to the material retention property. These compressive stresses result in wrinkling phenomenon in flange region. Normally blank holder is applied for restricting wrinkles. Tensile stresses in radial direction initiate thinning in the wall region of cup. The thinning results into cracking or fracture. The finite element method is widely applied worldwide to simulate the deep drawing process. For real-life simulations of deep drawing process an accurate numerical model, as well as an accurate description of material behavior and contact conditions, is necessary. The finite element method is a powerful tool to predict material thinning deformations before prototypes are made. The proposed innovative methodology combines two techniques for prediction and optimization of thinning in automotive sealing cover. Taguchi design of experiments and analysis of variance has been applied to analyze the influencing process parameters on Thinning. Mathematical relations have been developed to correlate input process parameters and Thinning. Optimization problem has been formulated for thinning and Genetic Algorithm has been applied for optimization. Experimental validation of results proves the applicability of newly proposed approach. The optimized component when manufactured is observed to be safe, no thinning or fracture is observed.