• Journal of Energy Engineering
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• v.29 no.3
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• pp.25-33
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• 2020

In this study, flow and structural computational analysis were performed to investigate the structural safety of the lightweight butterfly valve disc designed by topology optimization. After flow analysis, as the opening angle increased, the flow coefficient increased non-linearly and showed a gentle slop. When the opening angle was 12 degree, the cavitation could be predicted. After FE analysis, all FE von-Misses stresses of the lightweight disc were smaller than the yield strength of the material, and all FE maximum deformations were also smaller than the conservative deformation of the previous study. Ultimately, it was confirmed that the structural safety of the lightweight valve disc based on computational analysis is effective.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.3 s.14
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• pp.89-94
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• 2004

Recently, the cityward tendency of the population has caused the construction of a high rise apartment increased, because it is possible for many people to dwell on a small ground area in an apartment. In the future the number of the constructed high-rise apartment units will also increase, because many people require a better environment and more improved space of their life. However, apartment buildings with many dwellers in spite of small area are exposed to great dangers, particularly fire. So the adaptable control methods of smoke which is the most dangerous to people in a fire were proposed by an analysis on some standards for the fire in this study.

• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.1012-1021
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• 2005

This paper describes the design and implementation of an efficient multi-point multimedia conference system using IP grouping. Existing multi-point multimedia conference systems are difficult for multi-user to perform efficient cooperation due to bandwidth limitation for data transmission of video, audio and documentation. In the case that multi-user uses limited bandwidth, smooth cooperation does not accomplish due to transmission delay for the real-time transmission of image and speech data. A hybrid transfer method which is mixed with distributed and centralized methods is used for smooth cooperation, and the network bandwidth is reduced by forming multi-user conference systems of IP grouping in this paper. Also, adaptive image frame variations are used to solve bottleneck effect according to the number of users. An efficient multi-user conference system is designed to support audio quality.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.449-454
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• 1998

전립선 비대증 및 각종 고형암 조직을 제거하기 위해 이용되는 고강도 집속형 초음파 시스템은 초음파의 조직에 대한 열 효과를 이용한다. 이 경우 수MPa의 고 압력 초음파를 사용하기 때문에 수술시 초음파에 의한 조직내의 공동 현상이 수반되고 이로 인해 초음파의 집속 효과가 감소하게 된다. 본 논문에서는 초음파 공동 현상을 억제하기 위하여 초음파의 주파수 특성을 고려하였다. 초음파의 크기는 일정하게 유지하면서 증가하는 주파수로 변조된 초음파와 비선형 고저파 (nonlinear harmonics) 성분을 포함한 왜곡된 초음파에 대한 기포의 반응을 Gilmore 기포 모델을 이용하여 관찰하였다. 초음파의 주파수 변조는 10 $\mu\textrm{s}$ 동안 초기 주파수 1 MHz부터 시작하여 7 MHz까지 선형적으로 증가하도록 하였다. 파형을 왜곡시키는 고저파 성분의 크기는 주파수에 역 비례 하도록 하였다. 초음파의 기본 주파수는 1 MHz로 하였고, 압력은 0.1 MPa과 1 MPa의 두 경우를 고려하였다. 초기 기포의 반경은 1 $\mu\textrm{m}$으로 하였고, 기포 주위의 유체는 물로 가정하였다. 시뮬레이션 결과로부터, 주파수를 변조시키거나 파형을 왜곡시킨 초음파에 대한 기포의 진동은, 동일한 압력의 정현파에 대한 경우 보다 작은 것으로 나타났다. 주파수 변조된 초음파에 반응한 기포의 진동은 압력이 낮을 때 (0.1 MPa), 변조된 주파수가 기포의 공진 주파수인 3 MHz 부근에서 최대치를 보이다가 이후 급격히 감소하는 경향을 보였다. 반면, 압력이 높아지면 (1 MPa) 기포의 진동은 주파수의 증가와 함께 감소하다가 3 MHz 이상으로 변조 될 경우, 유의한 변화를 보이지 않는 것으로 나타났다. 이 결과는 초음파의 적절한 주파수 성분 조절로 초음파 공동 현상을 일정 수준 억제할 수 있음을 시사한다. 고려가 수반되어야 할 것으로 보인다. 다음 내용을 정리해 보고자 한다.리해 보고자 한다.rc$ 구입할 때 중점적으로 살펴보는 사항은 신선도와 순수재래종 여부, 위생상태였다. 한편 소비자가 언제나 구입할 수 없다는 의견이 85.2%나 되어 원활한 공급과 시장조성이 아직 정착되지 않고 있었다. $\bigcirc$ 현재 유통되고 있는 재래종닭은 소비자 대부분이 잡종으로 인식하고 있었으며, 재래종과 일반육계와의 구별은 깃털색, 피부색, 정강이색등 외관상으로 구별하고 있었다. 체중에 대한 반응은 너무 작다는 의견이었고, 식품으로의 인식도는 비교적 고급식품으로 인식하고 있다. $\bigcirc$ 재래종닭고기의 브랜드화에 대한 견해는 젊고 소득이 높은 계층에서 브랜드화의 필요성을 강조하고 있다. $\bigcirc$ 재래종달걀의 소비형태는 대부분의 소비자가 좋아하였으나 아직 먹어보지 못한 응답자가 많았다. 재래종달걀의 맛에 대해서는 고소하고 독특하여 차별성을 느끼고 있었다. $\bigcirc$ 재래종달걀의 구입장소는 계란판매점(축협.농협), 슈퍼, 백화점, 재래닭 사육 농장등 다양하였으며 포장단위는 10개를 가장 선호하였고, 포장재료는 종이, 플라스틱, 짚의 순으로 좋아하였다. $\bigcirc$ 달걀의 가격은 200원정도를 적정하다고 하였으며, 크기는 (평균 52g)는 가장 적당하다고 인식하고 있으며, 난각색은 대부분의 응답자가 갈색을 선호하였다. $\bigcirc$ 재래종달걀의 구입시 애로사항은 믿을수 없고, 구입장소를 몰라서, 값이 싸다 등이었고, 앞으로 신뢰할 수 있고 위생적인 생산 및 유통체계가 확립될 경우 더 많이 소비하겠다는 의견이었다. $\bigcirc$ 재래닭 판매업소(식당)의 판매형태는 66.7%인 대부분

• Journal of the KSME
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• v.35 no.4
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• pp.337-346
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• 1995

급변하는 기업 환경에 적절히 대응하여 기업의 궁극적인 목적인 이윤 추구의 극대화를 위해서는 단순한 노동생산성 향상, 국부적인 개선/합리화, 일부분의 전산화, 단위 공정의 자동화 등을 통한 부문별(기능별) 자동화로는 생산성 향상에 한계가 있을 것으로 여겨진다. 보다 체계적이고 종 합적으로 관련 업무를 추진하려면 진단 업무를 통하여 대상부문의 문제점들을 도출하여 그 문 제점들을 종합적으로 해결하는 차원에서 일관성 있게 추진하여야 될 것이다. 이러한 진단 활동을 통하여 체계적이고 효율적인 생산 시스템을 구축하려면 관련된 모든 부문의 현상 파악 및 문 제점 도출에 직접적으로 지원을 할 수 있는 핵심 요원으로 구성된 전담 추진 팀을 구성함은 물 론이고 전문 기관 또는 학계와 공동으로 추진하는 것이 효율적일 것으로 여겨진다. 현대중공업 에서는 이러한 요구에 적절히 대응하기 위하여 엔진사업본부의 POPICS와 플랜트 사업본부의 PINES가 학계와 공동연구로 추진 중에 있다. 이러한 일련의 TFT 활동을 통해 좋은 결실을 얻기 위해서는 참여하는 핵심 요원은 물론이고 해당되는 부문의 모든 임직원의 Mind 형성 및 적극적인 참여가 절실히 요구된다. 또한, 이와 같은 사업본부 단위의 대형 과제를 추진하려면 시스템화 지향이 우선 전제되어야 하기 때문에 부분적인 최적화 노력보다는 전체적인 접근이 필요할 것이다.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.172-176
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• 1998

Epoxy adduct carboxyl terminated butadiene acrylonitrile(CTBN) was prepared by blending of CTBN and epoxy resin. CTBN/PU/epoxy was prepared from polyurethane(PU), epoxy resin, and CTBN. The CTBN/PU/epoxy using 5 wt% of CTBN content showed shifting damping peak as PU content increased. It suggested that CTBN/PU/epoxy had good compatibility for all composition at 5 wt% of CTBN content. But miscibility of CTBN/PU/epoxy decreased with the increase of the CTBN content. PU content for maximum flexural properties of CTBN/PU/epoxy was 10 wt%, but decreased with the increase of the PU content. The fracture toughness of CTBN/epoxy was improved by addition of the PU. Fracture surfaces of CTBN/PU/epoxy showed the shear deformation and generation of stress whitening which is associated with the cavitation. Cavitation in the CTBN and shear defomation in the PU modified epoxy matrix are the toughening mechanisms for CTBN/PU/epoxy.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.199-210
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• 2003

The development of strain localization within shear zones is frequently observed during soil deformation. In fact, the phenomenon appears to be more often the norm rather than the exception. Conceptually, any soil condition that renders negative work increment is prone to localization. In this study, a broad range of soil and loading conditions are investigated to test this criterion, including: dilative soil subjected to drained shear (standard case), contractive soil sheared under undrained conditions, cavitation in dilative soil in undrained shear, inhomogeneous soils, particle alignment in contractive soils made of platy particles, soils that experience particle crushing, and the shear of low-moisture and/or lightly cemented loose soils. Unique specimens and test procedures are designed to separately test each of these soil conditions in the laboratory According to experimental test results, soil specimens with post-peak strain softening behavior are prone to progressive failure, localization of deformations, and shear banding. The state of stress, the soil density, inherent mechanical and geometrical properties of soil particles, low water content, and heterogeneity can contribute to triggering strain localization. Considering all possible cases of localization, the best method to obtain the critical state line in the laboratory is to use contractive homogeneous specimens subjected to drained shear.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.9-16
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• 2004

A three-dimensional numerical analysis was carried out on incompressible flows in butterfly valves by using commercial FLUENT/UNS code. Characteristics of complex flows including cavitation effect were investigated for different valve disk angles. The butterfly-valves that had different disk angles and different disk shapes were compared with each other in detail. This study focused on the flow analysis in the conventional butterfly valve and the newly designed butterfly valve in order to prevent cavitation. The newly designed valve shows great improvement on performance and endurance.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.4
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• pp.63-68
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• 2010

Utility-Pipe Conduit is, Housing and city effectively accommodate what they absolutely need power, communications, gas, pipeline, water supply, drainage, energy facilities etc, according to expansion of urban infrastructure are derived, several ways to solve problems in, collection facilities in place are maintained and managed facility. If Utility-Pipe Conduit is damaged, as well as national security, because their impact on society as a whole, by introducing large vulnerability in the fire prevention activities and suppression measures and disaster for our situation by introducing measures, comprehensive analysis of the fire risk, it shall establish fire prevention activities and suppression through analysis of Utility-Pipe Conduit design, institutional issues, the problem of fire protection facilities, fire spread phenomenon etc. Because of Utility-Pipe Conduit is an enclosed place, so incomplete combustion due to lack of oxygen supply that there are problem such dark smoke, carbon monoxide etc, toxic combustion products and heat generation and visual impairment is an issue difficult to enter. As well as fire prevention activities, the fire In light of the particularity of the under ground than above ground fire, so this phenomenon is weak fire fighting that fire to become effective fire fighting tactics, basically it is necessary difficulty softening, non-burn softening and prevent combustion expansion of the cable is installed on the Utility-Pipe Conduit, having to considering the specificity of the response command system and relevant organizations to establish an on-site, Structural identification and other information gathering required to record of Response agencies, keep air conditioning system 24 hours and strengthening Virtual Total Training of Response agen

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.376-378
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• 2011

Hamburg is going with the HafenCity Project to create new urban space for city's bustling central district. HafenCity will add an additional 155 hectares to Hamburg's central urban area, increasing its total area by some 40 percent. The new developments in HafenCity will be oriented towards the River Elbe and the great seaport. Its centre will have a close relation to water. They will be used for the construction of a fascinating mix of residential accommodation, offices, cultural and leisure amenities, retail facilities and restaurants set in a framework of an elaborate urban layout. This study is focusing on the purpose of the project goals, the task of the Hamburg authorities and GHS (Gesells chaft f$\ddot{u}$r Hafen und Standortentwicklung) and an urban planning ideas competition (draft masterplan). Regarding of the new trend of the reurbanisation in Europe, the aim of this study will be to find out, in which way Hafencity is trying to develope the new city district as a model for the European inner city of the 21st century.