• 한국해양공학회지
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• 제29권1호
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• pp.34-44
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• 2015

A hydraulic tensile test machine (HSTM) is one of the devices used to obtain the flow stress of a material during high-speed elongation. This paper first describes some features of a newly built HSTM. The improvement histories of the upper and lower jigs, which are the most vital parts of the HSTM, are also presented. We have frequently witnessed test failures with 1st generation jigs and specimens due to slip between the jig and specimen. 2nd generation jigs provide more stable test results, but the use of a longer upper jig induces excessive vibration and consequently makes it difficult to attach an environment chamber. 3rd generation jigs have some advances in terms of the symmetric fastening between the upper jig and specimen, as well as an exemption from direct contact between the lower jig and specimen. The performance of an environment chamber is verified by high and low temperature tests. A high-speed displacement measurement system is introduced based on a high-speed camera and motion-tracking software with aid of a surface grid device for the specimen.

• 한국컴퓨터그래픽스학회논문지
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• 제17권4호
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• pp.31-40
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• 2011

프로젝터 기반의 가시화 시스템은 가상현실 흑은 체험형 응용에서 널리 사용된다. 그러나 스크린 재질과 반사 성질에 따라 스크린 상의 투사 밝기의 불균일성이 때때로 체험자의 체험을 방해할 수 있다. 이러한 현상은 체험자의 위치를 추적하는 시스템인 CAVE 혹은 운동판 체험 시스템의 체험자가 시스템 안에서 계속적으로 움직일 경우에는 특별히 문제가 될 수 있다. 스크린 화상 상에 밝기의 불균일성을 만드는 이유 중에 하나는 참여자의 눈의 위치로의 프로젝터와 스크린의 스펙큘라 반사이며, 이에 대한 분석은 높은 계산 복잡도가 요구된다. 그래픽 프로세서의 프로그래머블 쉐이더를 이용하여 스펙큘라 라이팅 요소를 계산하는 것과 마찬가지로, 본 연구에서는 밝기의 불균일성을 줄이기 위하여 주어진 스크린 환경 3D 모델을 가지고 수행 시간에 모든 화소의 밝기를 조정하였다. 이러한 목적을 위하여 개개의 스크린 응용에 따른 각도 기반의 밝기 보정 함수를 고안하였으며, GPU 상에서 수행과 접근을 용이하도록 하였다. 두가지 기법이 구현되었는데, 각도 기반의 접근에서 프로덕트 기반의 접근으로 변환과 구간 선형 보간 근사 기법을 구현하였다.

• 한국도로학회:학술대회논문집
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• 한국도로학회 2002년도 학술발표회 논문집
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• pp.89-92
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• 2002

본 연구의 목적은 여러 가지의 폐자원중 슬래그 및 폐주물사의 도로포장용 골재로서의 특성을 평가하고, 이를 이용한 다양한 조합의 재활용 아스팔트 혼합물의 소성변형 특성을 평가하는 것이다. 골재특성을 평가하기 위해 입도 및 입형분석, 비중 및 흡수성, 마모저항성, 골재안정성과 같은 시험을 수행하였다. 골재로서의 특성평가 시험 결과 고로슬래그는 비교적 강도 특성이 제강슬래그에 비해 작은 경향을 나타냈다. 마샬배합설계로서 최적 아스팔트 함량이 결정되었고, 그 범위는 7.2%에서 7.5%정도 였다. 재활용 골재를 이용한 조합의 아스팔트 혼합물의 소성변형 특성을 평가하기 위해 간접인장강도시험, 회복탄성계수시험, 크리프 시험을 수행하였다. 재활용 골재를 이용한 아스팔트 혼합물의 소성변형 특성이 일반골재를 이용한 아스팔트 혼합물에 비해 다소 떨어지는 경향을 나타내었다. 다만 현재진행중인 휠트래킹 시험 결과가 나오면 재활용 골재를 활용한 아스팔트 혼합물의 소성변형특성을 좀더 구체적으로 파악할 수 있을 것으로 판단된다.

• 한국도로학회논문집
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• 제12권4호
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• pp.203-209
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• 2010

서울시내 도로 유지보수 4개 현장에서 수집된 재령 및 물리적 특성이 서로 다른 폐아스팔트를 폼드 아스팔트 공법을 사용하여 기층용 혼합물을 제작하였다. 혼합물은 구재와 신재의 비율을 서로 달리하여 제작하였으며 구재 비율 변화에 따른 성능을 실내시험을 실시하여 분석하였다. 실내시험은 마샬안정도, 간접인장강도, 회목탄성계수, 크리프 시험 및 휠 트레킹 시험을 실시하였으며 시험 결과는 재생가열 아스팔트 혼합물 시험 결과와 상호 비교하였다. 비교 결과, 재생 폼드 아스팔트 혼합물은 소성변형 및 온도 변화에 대한 저항성은 재생 가열 아스팔트 혼합물에 비하여 동등하거나 우수한 것으로 나타났다. 한편 재생 폼드 아스팔트 혼합물의 건조시 간접인장강도는 재생 가열 아스팔트 혼합물에 비하여 낮게 측정되었으며 습윤시에는 구재의 비율과 관계없이 모두 간접인장강도가 낮게 나타나서 습윤 조건에서는 취약한 것으로 발견되었다.

• 한국환경과학회지
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• 제25권8호
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• pp.1087-1095
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• 2016

The concepts of residence time and flushing time can be used to explain the exchange and transport of water or materials in a coastal sea. The application of these transport time scales are widespread in biological, hydrological, and geochemical studies. The water quality of the system crucially depends on the residence time and flushing time of a particle in the system. In this study, the residence and flushing time in Gamak Bay were calculated using the numerical model, EFDC, which includes a particle tracking module. The average residence time was 55 days in the inner bay, and the flushing time for Gamak Bay was about 44.8 days, according to the simulation. This means that it takes about 2 months for land and aquaculture generated particles to be transported out of Gamak Bay, which can lead to substances accumulating in the bay. These results show the relationships between the transport time scale and physical the properties of the embayment. The findings of this study will improves understanding of the water and material transport processes in Gamak Bay and will be important when assessing the potential impact of coastal development on water quality conditions.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.320-323
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• 2002

This paper presents a new generation of system for pressure vessel and shipbuilding. Typical pressure vessel and ship building weld joint preparations are either traditional V, butt, fillet grooves or have narrow or semi narrow gap profiles. The fillet and U groove are prevalently used in heavy industries and shipbuilding to melt and join the parts. Since the wall thickness can be up to 6" or greater, welds must be made in many layers, each layer containing several passes. However, the welding time for the conventional processes such as SAW(Submerged Arc Welding) and FCAW(Flux Cored Arc Welding) can be many hours. Although SAW and FCAW are normally a mechanized process, pressure vessel and ship structures welding up to now have usually been controlled by a full time operator. The operator has typically been responsible for positioning each individual weld run, for setting weld process parameters, for maintaining flux and wire levels, for removing slag and so on. The aim of the system is to develop a high speed welding system with multitorch for increasing the production speed on the line and to remove the need for the operator so that the system can run automatically for the complete multi-torch multi-layer weld. To achieve this, a laser vision sensor, a rotating torch and an image processing algorithm have been made. Also, the multitorch welding system can be applicable for the fine grained steel because of the high welding speed and lower heat input compare to a conventional welding process.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.635-641
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• 2016

Because of prohibitive data storage requirements in large-scale simulations, the memory problem is an obstacle for Monte Carlo (MC) codes in accomplishing pin-wise three-dimensional (3D) full-core calculations, particularly for whole-core depletion analyses. Various kinds of data are evaluated and quantificational total memory requirements are analyzed based on the Reactor Monte Carlo (RMC) code, showing that tally data, material data, and isotope densities in depletion are three major parts of memory storage. The domain decomposition method is investigated as a means of saving memory, by dividing spatial geometry into domains that are simulated separately by parallel processors. For the validity of particle tracking during transport simulations, particles need to be communicated between domains. In consideration of efficiency, an asynchronous particle communication algorithm is designed and implemented. Furthermore, we couple the domain decomposition method with MC burnup process, under a strategy of utilizing consistent domain partition in both transport and depletion modules. A numerical test of 3D full-core burnup calculations is carried out, indicating that the RMC code, with the domain decomposition method, is capable of pin-wise full-core burnup calculations with millions of depletion regions.

• 한국도로학회논문집
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• 제3권4호
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• pp.105-116
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• 2001

본 연구는 주물고사를 이용한 아스팔트 콘크리트와 주물고사의 물리적 화학적 특성을 비교 분석하는 것이다. 주물고사의 아스팔트 콘크리트 적용성을 평가하기 위하여 XRF, SEM, 제타전위를 측정하여 주물고사의 물리 화학적 특성을 알아보았다. 주물고사 아스팔트 콘크리트의 박리저항성을 향상시키기 위하여 박리방지제(소석회(Hydrated lime), 액상박리방지제)를 사용하였다. 그리고 주물고사 아스팔트 콘크리트 혼합물의 인장특성과 내구성 향상을 위하여 LDPE를 사용하였다. 또한 주물고사 아스팔트 콘크리트의 공용성을 알아보기 위하여 간접인장강도, 수분취약성시험, 동결 융해시험, 반복주행시험을 수행하였다. 시험결과 주물고사 아스팔트 콘크리트의 역학적 특성이 일반 아스팔트 콘크리트에 비해 같거나 향상되는 것으로 나타났다. 따라서 주물고사를 아스팔트 콘크리트에 재활용할 수 있다는 결론을 얻었다.

• Smart Structures and Systems
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• 제18권5호
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• pp.955-982
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• 2016

Recent studies integrating vibration control and structural health monitoring (SHM) use control devices and control algorithms to enable system identification and damage detection. In this study real-time SHM is used to enhance structural vibration control and reduce damage. A newly proposed control algorithm, including integrated real-time SHM and semi-active control strategy, is presented to mitigate both damage and seismic response of the main structure under strong seismic ground motion. The semi-active independently variable stiffness (SAIVS) device is used as semi-active control device in this investigation. The proper stiffness of SAIVS device is obtained using a new developed semi-active control algorithm based on real-time damage tracking of structure by damage detection algorithm based on identified system Markov parameters (DDA/ISMP) method. A three bay five story steel braced frame structure, which is equipped with one SAIVS device at each story, is employed to illustrate the efficiency of the proposed algorithm. The obtained results show that the proposed control algorithm could significantly decrease damage in most parts of the structure. Also, the dynamic response of the structure is effectively reduced by using the proposed control algorithm during four strong earthquakes. In comparison to passive on and off cases, the results demonstrate that the performance of the proposed control algorithm in decreasing both damage and dynamic responses of structure is significantly enhanced than the passive cases. Furthermore, from the energy consumption point of view the maximum and the cumulative control force in the proposed control algorithm is less than the passive-on case, considerably.

• Preventive Nutrition and Food Science
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• 제11권4호
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• pp.348-357
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• 2006

Nano is a unit that designates a billionth; accordingly nanotechnology could be described as the study and applications of the unique characteristics and phenomena of nanometer size materials. Applications of nanotechnology fall into two categories (one is top-down and the other is bottom-up). Currently, most products are the results of the top-down approach. Nanofoods have distinct functional characteristics stemming from the size, mass, chemical combinations, electrolytic features, magnetic properties of food sources at the nano level and which can be applied for safe absorption and delivery into the body. The greatest advantage of nanofood is that it permits the efficient use of small quantities of nutritional elements by increasing digestive absorption ability and by delivering natural elements without any change in their original characteristics. On the other hand, there are still unsolved problems, such as questions about safety and introduction of harmful material. The demand for new commercial food products is increasing, and commercial food producers are gradually combining nanotechnology and traditional food preparation methods. Nanofoods will improve our eating habits remarkably in the future. Tomorrow we will design nanofoods by shaping molecules and atoms. It will have a big impact on the food and food-processing industries. The future belongs to new products and new processes with the goals of customizing and personalizing consumer products. Nanotechnology is expected to be applied to not only foods themselves, but also to food packaging, production, safety, processing and storage. Also, it is believed that nanotechnology will be applied tracking finished products back to production facilities and even to specific processing equipment in those facilities. The aim of this study is the introduction of technology, applications, products, markets, R&D, and perspectives of nanofoods in the food industry.