• 한국유체기계학회 논문집
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• 제4권3호
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• pp.7-13
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• 2001

The present study investigates convective heat/mass transfer and flow characteristics inside a cooling passage of rotating gas-turbine blades. The rotating duct has staggered ribs with $70^{\circ}$ attack angle, which are attached on leading and trailing surfaces. Naphthalene sublimation technique is employed to determine detailed local heat transfer coefficients using the heat and mass transfer analogy. Additional numerical calculations are conducted to analyze the flow patterns in the cooling passage. The present experiments employ two-surface heating conditions in the rotating duct because the exposed surfaces to hot gas stream are pressure and suction side surfaces in the middle passages of an actual gas-turbine blade. Secondary flows are generated by Coriolis and centrifugal forces in the spanwise and streamwise directions. The ribs attached on the walls disturb the mainflow resulting in recirculation and secondary flows near the ribbed wall. The local heat transfer and flow patterns in the passage are changed significantly according to rib configurations and duct rotation speeds. Therefore, the geometry and arrangement of the ribs are important for the advantageous cooling performance. The experimental results show that the ribs enhance the heat transfer more than $70\%$ from that of the smooth duct. The duct rotation generates the heat transfer discrepancy between the leading and trailing walls due to the secondary flows induced by the Coriolis force. The overal heat transfer pattern on the leading and trailing walls for the first and second passes are depended on the rotating speed, but the local heat transfer trend is affected mainly by the rib arrangements.

• 한국수소및신에너지학회논문집
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• 제29권2호
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• pp.197-204
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• 2018

In the present study, unsteady flow analysis has been conducted to investigate the blade forces and wake flow around a hybrid street-lamp having a vertical-axis small wind turbine and a photovoltaic panel. Uniform velocities of 3, 5 and 7 m/s are applied as inlet boundary condition. Relatively large vortex shedding is formed at the wake region of the photovoltaic panel, which affects the increase of blade torque and wake flow downstream of the wind turbine. It is found that blade force has a good relation to the variation of the angle of attack with the rotation of turbine blades. Variations in the torque on the turbine blade over time create a cyclic fluctuation, which can be a source of turbine vibration and noise. Unsteady fluctuation of blade forces is also analyzed to understand the nature of the vibration of a small wind turbine over time. The detailed flow field inside the turbine blades is analyzed and discussed.

• Advances in materials Research
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• 제9권3호
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• pp.233-250
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• 2020

In this study, a chitosan based coating method was developed and applied on the shoe lining leather surface for evaluating its inhibition to bacterial and fungal attacks. At first, chitosan was prepared from raw prawn shells and then the prepared chitosan solution was applied onto the leather surface. Secondly, the characterization of the prepared chitosan and chitosan treated leather was performed by solubility test, ATR-FTIR, XRD pattern, SEM and TGA. Evaluation of antimicrobial efficacy of chitosan was assessed against two gram positive, two gram negative bacteria and a reputed fungi by agar diffusion test. The results of this study demonstrated that chitosan took place in both the surface of collagen fibres and inside the collagen matrix of crust leather. The chitosan showed strong antimicrobial activities against all the tested microorganisms and the inhibition increased with increasing percentage of chitosan. Therefore, the prepared chitosan in this study can be an environment friendly biocide, which functions simultaneously against different spoilage bacteria and fungi on the finished leather surface. Thus by using the prepared chitosan in shoe lining leather, the possibility of microbial attack during shoe wearing can be minimized which is one of the important hygienic requirements of footwear.

• 한국콘텐츠학회논문지
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• 제11권8호
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• pp.142-149
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• 2011

본 연구는 국내의 대표적 유가공(乳加功) 기업인 파스퇴르의 유산균 발효유 '쾌변 요구르트'에 대한 스토리텔링 캠페인 사례를 분석하였다. 파스퇴르의 스토리텔링 캠페인은 브랜딩과 포지셔닝 개발에 초점을 두었다. 브랜딩과 포지셔닝은 소비자 관점에서 브랜드전략을 수립하는 브랜드 스튜어드쉽 모델(Brand Stewardship Model;BSM)을 활용하여 설계하였다. BSM 분석결과, '쾌변 요구르트'라는 브랜드 네임이 탄생되었는데 그 배경은 후발주자로써 단기간 동안 소비자 이익을 대변할 수 있어야 한다는 것과 제품의 핵심가치인 '쾌변'을 브랜드화 해야 한다는 것이었다. 파스퇴르는 '쾌변'이라는 신제품의 브랜드명에 대한 부담을 완화하고, 짧은 기간 동안 브랜드 인지도를 확산시키기 위한 포지셔닝을 설정하였다. 최종적으로 결정된 '쾌변 요구르트'의 포지셔닝은 '안 나오면 쳐들어 간다'이다. 그 근거는, 소비자에게 익숙한 멜로디를 상징적으로 표현함으로써, 배변에 좋은 '쾌변'이라는 브랜드 이미지를 강화하는 것이다. 특히, 캠페인 초기 티저광고 형태로 집행된 '안 나오면 쳐들어 간다'는 신제품을 포지셔닝하는데 결정적으로 기여했다. 즉, 파스퇴르 사례는 브랜딩과 포지셔닝 간의 전략적 조합이 스토리텔링 캠페인에서 얼마나 중요한가를 증명했다는 의미에서 연구의 가치가 있다고 하겠다.

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.20-24
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• 2015

Steam generator(S/G) tubes in pressurized water reactor (PWR's) are subject to several types of degradation. This degradation includes denting, pitting, intergranular attack(IGA), intergranular stress corrosion cracking(IGSCC), fatigue, fretting and wear. Degradation can be derived from either the primary side(inside) or the secondary side(outside) of the tube. Recent issue for tube degradation in domestic steam generator is the tube end cracking on seal weld region. The seal weld region at the tube end and tube itself is regarded as a pressure boundary between the primary side and the secondary side. One of the Westinghouse Model-F S/G has experienced tube end cracking and its number of plugging approximately becomes to the operating limit up to 5% due to tube end cracking which was reported as SAI/MAI(single/multiple axial indication) or SCI/MCI(Single/multiple circumferential indication) from the results of eddy current testing. Eddy current mock-up test was carried out to determine the origin of cracking whether it is from weld zone area or parent tube. This result was helpful to analyze crack location on ECT data. Correct action on this problem was the installation of tube-end sleeve. Last year, after removing 340 installed plugs from tubes, selected 269 tubes took tube-end sleeve installation. Tube-end sleeve brought pressure boundary from parent tube to installed sleeve tube. Tube-end sleeve has the benefit of reducing outage period and increasing more revenue than replacing S/G. This paper is provided to assist interest parties in effectively understanding this issue.

• 대한기계학회논문집B
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• 제30권9호
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• pp.921-928
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• 2006

Wake-induced boundary-layer transition on a NACA0012 airfoil with zero angle of attack is experimentally investigated in periodically passing wakes under the moderate level of free-stream turbulence. The periodic wakes are generated by rotating circular cylinders clockwise or counterclockwise around the airfoil. The free-stream turbulence is produced by a grid upstream of the rotating cylinder, and its intensities $(Tu_{\infty})$ at the leading edge of the airfoil are 0.5 and 3.5%, respectively. The Reynolds number (Rec) based on chord length (C) of the airfoil is $2.0{\times}10^5$, and Strouhal number (Stc) of the passing wake is about 1.4. Time- and phase-averaged streamwise mean velocities and turbulence fluctuations are measured with a single hot-wire probe, and especially, the corresponding wall skin friction is evaluated using a computational Preston tube method. The patch under the high free-stream turbulence $(Tu_{\infty}=3.5%)$ grows more greatly in laminar-like regions compared with that under the low turbulence $(Tu_{\infty}=0.5%)$ in laminar regions. The former, however, does not greatly change the turbulence level in very near-wall region while the latter does it. At further downstream, the former interacts vigorously with high environmental turbulence inside the pre-existing transitional boundary layer and gradually loses its identification, whereas the latter keeps growing in the laminar boundary layer. The calmed region is more clearly observed under the lower free-stream turbulence level and with the receding wakes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5642-5670
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• 2017

Antivirus is an important issue to the security of virtual machine (VM). According to where the antivirus system resides, the existing approaches can be categorized into three classes: internal approach, external approach and hybrid approach. However, for the internal approach, it is susceptible to attacks and may cause antivirus storm and rollback vulnerability problems. On the other hand, for the external approach, the antivirus systems built upon virtual machine introspection (VMI) technology cannot find and prohibit viruses promptly. Although the hybrid approach performs virus scanning out of the virtual machine, it is still vulnerable to attacks since it completely depends on the agent and hooks to deliver events in the guest operating system. To solve the aforementioned problems, based on in-memory signature scanning, we propose an agentless runtime antivirus system VirtAV, which scans each piece of binary codes to execute in guest VMs on the VMM side to detect and prevent viruses. As an external approach, VirtAV does not rely on any hooks or agents in the guest OS, and exposes no attack surface to the outside world, so it guarantees the security of itself to the greatest extent. In addition, it solves the antivirus storm problem and the rollback vulnerability problem in virtualization environment. We implemented a prototype based on Qemu/KVM hypervisor and ClamAV antivirus engine. Experimental results demonstrate that VirtAV is able to detect both user-level and kernel-level virus programs inside Windows and Linux guest, no matter whether they are packed or not. From the performance aspect, the overhead of VirtAV on guest performance is acceptable. Especially, VirtAV has little impact on the performance of common desktop applications, such as video playing, web browsing and Microsoft Office series.

• 건축역사연구
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• 제16권6호
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• pp.47-66
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• 2007

$Lokap{\bar{a}}las$ are understood as the deities of four directions in Buddhism: $Dhrtar{\bar{a}}stra$ in the East, $Vir{\bar{u}}dhaka$ in the South, $Vir{\bar{u}}p{\bar{a}}ksa$ in the West and $Vai{\acute{s}}ravana$ in the North respectively. Their common name is, therefore, called as the "Four Guardian Kings", whose function is to prevent demonic forces from entering into its sacred world. Although the position of $Lokap{\bar{a}}las$ is to the lowest level in the hierarchy of the minor deities in Buddhism, the cult of $Lokap{\bar{a}}las$ was widely spread and prominent in the countries of Northern Buddhism. It played a significant role in terms of the state-protecting Buddhism, on behalf of it's esoteric and magic power. More than 20 Gateways of the $Lokap{\bar{a}}las$ and $Lokap{\bar{a}}la$ statues were still well preserved in Korea, and they were believed to be constructed after the Japanese attack in 1592. After war, monks had concentrated on restoring ruined temples and building many new Gateways of the Four Guardian Kings over the Korean peninsular. Under such circumstances, even though the $Lokap{\bar{a}}las$ played a significant role as the subject of cult in Korean Buddhism. they might have a small chance to be taught traditional Lama iconography exactly. The purpose of this essay is to examine the relation of orientation of the Gate way of $Lokap{\bar{a}}las$ and allocation of each Kings inside the gate.

• 정보보호학회논문지
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• 제26권6호
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• pp.1471-1481
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• 2016

최근 IoT에 대한 관심이 급증함에 따라 다양한 IoT 서비스들이 출시되고 있다. 그 중 스마트홈은 사용자의 주거공간에 IoT를 접목함으로써 우리의 생활과 매우 밀접하게 연관되어 있다. 그렇기 때문에, 정당하지 않은 사용자가 스마트홈 내부의 디바이스에 접근한다면, 일상생활과 매우 밀접한 만큼 사용자에게 더 큰 피해를 입힐 수 있다. 예를 들어 스마트홈 내부의 도어락에 인증되지 않은 공격자가 접근하여 명령을 수행할 수 있게 된다면, 주거 침입의 형태로 큰 재산 피해를 입을 수도 있다. 이를 방지하기 위해 본 논문에서는 패스워드 기반의 인증 및 키 교환(PAKE)을 이용하여 사용자와 디바이스가 홈 게이트웨이를 통해 인증과 키 교환을 할 수 있는 3자간 PAKE(3PAKE) 기법을 제안한다.

• Journal of Acupuncture Research
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• 제17권2호
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• pp.85-93
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• 2000

We came to the conclusion after considering all the information from many kinds of books on the circulation courses, cross-link points, functions and the symptoms of disease of Chongmai. The results were as follows : 1. The Chongmai that starts from a Uterus flows to Dazhu through the inside of vertebra after joining Renmai and Duimai at Huiyin. The Chongmais up-line that comes out from Qichong into a surface of body arrives and is scattered at a chest through an abdomen. One strand of them goes upward again and is connected to a throat and lips area. After coming out from Qichong, separated down-line is divided into two parts when it arrives a inner part of a heel through the inner part of a leg. One is for an instep, the other is for the sole of a foot. 2. We call it "Sea of Twelve Meridians" or "Meridian's Sea". Because Chongmai controls all of Meridian by acquired "Basic energy" as getting Stomach's energy, Kidney's energy and air-energy, and there are responsible of physiological phenomenon control. And also we name it "Sea of Blood", because it starts from and provides a nutrition to Uterus. 3. All of these four Meridian such as Renmai, Kidney Meridian, Stomach Meridian and Spleen Meridian are ones that flow around the part of a chest and an abdomen. Chongmai makes energy and blood circulation of a chest and an abdomen be stronger and be controlled. Therefore it makes viscera, bowels and body surface be warm and given a nutrition. So Chongmai becomes "Sea of Viscera and Bowels". 4. Chongmai provides a nutrition for ligament and muscle and makes legs get warm as making energy and blood circulate from head to foot. If Chongmai is energetic, hair is completely easy to grow. 5. To see in pathological phase, Chongmais failure or weakness causes like a chest pain, stomachache, heart attack, a menstrual irregularity and sterility and so on. And also if Chongmai is damaged, it happens that giving a nutrition for lips area is stopped, and then mustache doesn't grow any more.