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A Study on Aerodynamic Characteristics of Flapping Motion (플래핑 운동의 공기역학적 특성에 관한 연구)

  • Kim Yoon-Joo;Oh Hyun-Taek;Chung Jin Taek;Choi Hang-Cheol;Kim Kwang-Ho
    • Journal of the Korean Society of Visualization
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    • v.3 no.2
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    • pp.63-70
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    • 2005
  • Birds and insects flap their wings to fly in the air and they can change their wing motions to do steering and maneuvering. Therefore, we created various wing motions with the parameters which affected flapping motion and evaluated the aerodynamic characteristics about those cases in this study. As the wing rotational velocity was fast and the rotational timing was advanced, the measured aerodynamic forces showed drastic increase near the end of stroke. The mean lift coefficient was increased until angle of attack of 5050 and showed the maximum value of 1.0. The maximum mean lift to drag ratio took place at angle of attack of 2020. Flow fields were also visualized around the wing using particle image velocimetry (PIV). From the flow visualization, leading-edge vortex was not shed at mid-stroke until angle of attack of 5050. But it was begun to shed at angle of attack of 6060.

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A study on the Yeo Bub Eui (I) - focused on the colour of Kasa - (여법의에 관한 연구(I) - 가사색을 중심으로 -)

  • An Myung-Sook;Lee Chun-Gye
    • Journal of the Korean Society of Clothing and Textiles
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    • v.13 no.3 s.31
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    • pp.252-258
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    • 1989
  • The purpose of this study was to investigate the general Kasa. More specially, the objectives of the research was (a) to determine the reason why dyes the colour of kasa; (b) to examine the kinds of Kasa colour; (c) to provide the dyeing method of Kasa colour; (d) to clarify the prohibited colour and the permitted limit; and (e) to find which and why kasa colour in our country use. The reason why dyes the colour of Kasa are the following; (a) it differentiates between the white robe in the leading ascetic life of Buddhism at ones home and that of the entering the priesthood. (b) it protects the victim of robbery (c) it discards the attachment to the ownership (d) it lessens the burden of at alms. The kinds of Kasa's color consist of several one such as 증(cheung), 흑(heuk), 전(chun), 목란(mokran), and so on. The three colour among them use as the colour of kasa in the each vinaya pitaka. The dyeing method of kasa is composed of two ways; One is to dye the whole Kasa; the other is to dye the part of Kasa. Recently, in our country, the red which is the branch of kalasama is the leading colour of Kasa.

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On the Development of Reference Guidelines for Self-evaluation of Organization's Systems Engineering and Project Management Capability (조직의 SEPMC 자체 평가에 유용한 참조기준 개발)

  • Choi, Young Gil;Lee, Jae Chon
    • Journal of the Korean Society of Systems Engineering
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    • v.8 no.2
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    • pp.27-36
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    • 2012
  • In modern systems, the operational capability of the system to the user needs is expanding rapidly to accommodate the size of the system, functionality, and interfaces are becoming increasingly complex. Accordingly, the systematic practice of project management and systems engineering in the system development process, as an important element in successful systems development is recognized. EIA/ANSI 632, ISO/IEC15288, the leading international standard for systems engineering and is the leading international standard on project management PMBOK. CMMI is also contains information about the activities of project management and systems engineering and worldwide basis to assess the maturity of an organization's ability to develop system being used. But CMMI model is too complex of structure and there are many overlap parts of contents. So there are many problems for members of organization understanding all of CMMI model, applying organization and, achieving improvement activity. In this study, through the analysis and integration between the model and the related standard coverage activities essential for successful systems development in organizations that require systems engineering and project management capabilities(SEPMC) for self-assessment and continuous improvement activities to provide useful reference guideline.

Pioneering the Distribution Industry in Korea: Dynamic Capability at Lotte Shopping

  • Won, Eugene J.S.
    • Journal of Distribution Science
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    • v.16 no.10
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    • pp.5-21
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    • 2018
  • Purpose - This case study reviews the development history of Lotte Shopping, which has played a key role in modernizing Korea's retail industry. Research design, data, and methodology - Lotte Shopping's expansion to various channel types has been reviewed from the perspective of the resource-based view of strategy. The opening of Lotte Department Store in 1979 signaled the beginning of the modernized distribution system in Korea. Lotte Shopping expanded its business domains to various types of retail channels, such as discount stores, online shopping malls, TV home shopping, convenience stores, supermarkets, home appliances specialty stores and health & beauty stores. Results - Lotte Shopping has been able to maintain high level of customer satisfaction with leading merchandising skills. It has developed mutually beneficial relationship with the partner firms. It has also been a leading firm in implementing corporate social responsibility activities and environment-friendly management. Lotte Shopping has applied advanced information and communication technology to provide customized goods/services. Conclusions - This study summarizes the business environment and new challenges Lotte Shopping faces currently. Lotte Shopping is trying to reinforce the omni-channel strategy, which can create synergy among various distribution channels based on its core competences.

Validation of the Turbulent Burning Velocity Based on Asymptotic Zone Conditional Transport in Turbulent Premixed Combustion (영역조건평균에 기초한 난류예혼합 화염 전파 속도식 유도 및 검증)

  • Lee, Dong-Kyu;Huh, Kang-Y.
    • Journal of the Korean Society of Combustion
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    • v.13 no.1
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    • pp.23-30
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    • 2008
  • An analytical expression for the turbulent burning velocity is derived from the asymptotic zone conditional transport equation at the leading edge. It is given as a sum of laminar and turbulent contributions, the latter of which is given as a product of turbulent diffusivity in unburned gas and inverse scale of wrinkling at the leading edge. It was previously shown that the inverse scale is equal to four times the maximum flame surface density in the wrinkled flamelet regime [1]. The linear behavior between UTUT and u' shows deviation with the inverse scale decreasing due to the effect of a finite flamelet thickness at higher turbulent intensities. DNS results show that UT/S0LuUT/S0Lu may be given as a function of two dimensionless parameters, u/S0Lu and lt/δF, which may be transformed into another relationship in terms of u/S0Lu, and Ka. A larger lt/δF or a smaller Ka leads to a smaller scale of wrinkling, hence a larger turbulent burning velocity in the limited range of u/S0Lu. Good agreement is achieved between the analytical expression and the turbulent burning velocities from DNS in both wrinkled and thickened-wrinkled flame regimes.

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A Study on the Local Regression Rate of Solid Fuel in Hybrid Rocket (하이브리드 로켓에서의 고체연료의 국부 후퇴율에 관한 연구)

  • Kim, Soojong;Lee, Jungpyo;Kim, Gihun;Cho, Jungtae;Kim, Hakchul;Woo, Kyoungjin;Moon, Heejang;Sung, Hong-Gye;Kim, Jin-Kon
    • Journal of Aerospace System Engineering
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    • v.2 no.4
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    • pp.1-6
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    • 2008
  • In generally, the regression rate was expressed with average value and oxidizer mass flux in hybrid propulsion system. This can not represent the local value of regression rate along with oxidizer flow direction. In this study, experimental studies were performed with Separation method and Cutting method for measure local regression rate. In axial injection, the local regression rate decreases rapidly with axial location near entrance and increases with axial direction from the leading edge and the empirical formula for local regression rate with function of oxidizer mass flux and location was derived. Swirl injection regression rate has higher value at the leading edge of the fuel and comparatively uniform regression rate at the downstream. Overall regression rate of swirl injection is higher increased about 54 % than regression rate of axial injection.

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A study on the Productivity Management System of small and medium sized companies (중소기업의 생산성 경영시스템에 관한 연구)

  • Kim, Sok-Eun;Oh, Seon-Il;Kang, Kyung-Sik
    • Journal of the Korea Safety Management & Science
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    • v.10 no.3
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    • pp.155-166
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    • 2008
  • Advanced countries worldwide lead government leading management innovation by suggesting unique managing system which can be survived in global economy war including JQA of Japan and EFQM of Europe based basically on MBNQA of U.S.A. and by rewarding to suitable companies. Mckinsey, global management and consulting company points out that Korea has no management because Korean productivity level which dependence to small and medium sized companies is high by the limitation of elemental invests leading type growth strategy including labor and capital is only 1/2 of U.S.A. and 2/3 of Japan. In particular, the competitive power of Korean small and medium sized companies goes into a recession by productivity lowering according to the chinese follow-up, laboring time shortening, variety and aging, and fundamental management innovation activities for reinforcing survival and competitive power are needed. Therefore, in this study, we try to construct the model of productivity managing system of innovation type small and medium sized companies which make excellent results.

Flow Visualization in Realistic Arterial Bypass Graft Model

  • Singh, Megha;Shin, Se-Hyun
    • International Journal of Vascular Biomedical Engineering
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    • v.3 no.1
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    • pp.1-5
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    • 2005
  • Background: Coronary atherosclerosis artery disease is the leading cause of morbidity and mortality. Coronary artery bypass grafting (CABG) which utilizes the saphenous vein graft, has helped in alleviating the suffering of these patients. Newer techniques are being developed to improve upon the techniques. Still there is significant number of failures, leading to re-grafting or re-vascularization. Some studies have helped in identifying the high and low shear stress regions. Further studies based on their realistic models are required. Material, methods and results: we developed the realistic model of fully blocked right coronary with bypass graft placed at angle of 50 with curvature similar to that of artery. Pulsatile flow of birefringent solution through this model by polarized light was visualized. The images of complete flow field in the model were recorded and analyzed. Regions of high flow disturbances which are prone to further changes are identified. Existence of recirculation in the blocked coronary may initiate new blood-tissue interactions deleterious to bypass graft. Conclusion: Our study shows that by selecting the procedure to place bypass graft at minimum angle with curvature similar to that of artery and smooth sutures may improve the life span of the graft. This study also identified that coronary blocked regions contributing by recirculation flow at the proximal and distal regions of bypass which may require further studies.

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Inverse Eigenvalue Problems with Partial Eigen Data for Acyclic Matrices whose Graph is a Broom

  • Sharma, Debashish;Sen, Mausumi
    • Kyungpook Mathematical Journal
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    • v.57 no.2
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    • pp.211-222
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    • 2017
  • In this paper, we consider three inverse eigenvalue problems for a special type of acyclic matrices. The acyclic matrices considered in this paper are described by a graph called a broom on n + m vertices, which is obtained by joining m pendant edges to one of the terminal vertices of a path on n vertices. The problems require the reconstruction of such a matrix from given partial eigen data. The eigen data for the first problem consists of the largest eigenvalue of each of the leading principal submatrices of the required matrix, while for the second problem it consists of an eigenvalue of each of its trailing principal submatrices. The third problem has an eigenvalue and a corresponding eigenvector of the required matrix as the eigen data. The method of solution involves the use of recurrence relations among the leading/trailing principal minors of λIA, where A is the required matrix. We derive the necessary and sufficient conditions for the solutions of these problems. The constructive nature of the proofs also provides the algorithms for computing the required entries of the matrix. We also provide some numerical examples to show the applicability of our results.

Survey of Peat Deposits in Skhalin Island (사할린도(島)의 PEAT 현황조사)

  • Lee, Y.H.
    • Korean Journal of Soil Science and Fertilizer
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    • v.27 no.4
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    • pp.315-320
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    • 1994
  • This survey report introduced briefly peat deposits in SAKHALIN island of eastern SIBERIA continent. Peat industry was promoted as leading resources for development in this island by national control economic plan of central government before CIS. But development of deposit was left suspension of operation due to investment now. In southern area, about 10km from Yuzunosakhalinsk, two deposits of peat field were explored. One of them (Troisk) was suspended at begining stage of peat harvest from 300ha field and the other(Missilop) was producing the compact peat through drying and pulverizing from 350ha peat field which showed long run harvest activities. There are plenty of peat deposits near the Polonai Reika (river) in the central area of this island, At Zbaikaritz, 40km nothern area from Polonaisk, 135ha of peat field was developed. This field was left without working but established field preparation and could be able to be harvested any time if machines and utlities were settled. At southern suburb 10km from Polonaisk, about 40ha field of virgin deposit has been established planning for development. The plan involved estimated amount of peat, deposit depth, water level, drainage and leading road. The most of peat deposits accumulated from sphagnum moss. Texture is coarse but it contains more than 95% of organic carbon near to 0.5% of total nitrogen and acidity showed pH4-5.

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