• 한국환경농학회:학술대회논문집
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• 한국환경농학회 2009년도 정기총회 및 국제심포지엄
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• pp.228-239
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• 2009

The observations on climate change show a clear increase in the temperature of the Earth's surface and the oceans, a reduction in the land snow cover, and melting of the sea ice and glaciers. The effects of climate change are likely to include more variable weather, heat waves, increased mean temperature, rains, flooding and droughts. The threat of climate change and global warming on human and animal health is now recognized as a global issue. This presentation is described an overview of the latest scientific knowledge on the impact of climate change on zoonotic diseases. Climate strongly affects agriculture and livestock production and influences animal diseases, vectors and pathogens, and their habitat. Global warming are likely to change the temporal and geographical distribution of infectious diseases, including those that are vector-borne such as West Nile fever, Rift Valley fever, Japanese encephalitis, bluetongue, malaria and visceral leishmaniasis, and other diarrheal diseases. The distribution and prevalence of vector-borne diseases may be the most significant effect of climate change. The impact of climate change on the emergence and re-emergence of animal diseases has been confirmed by a majority of countries. Emerging zoonotic diseases are increasingly recognized as a global and regional issue with potential serious human health and economic impacts and their current upward trends are likely to continue. Coordinated international responses are therefore essential across veterinary and human health sectors, regions and countries to control and prevent emerging zoonoses. A new early warning and alert systems is developing and introducing for enhancing surveillance and response to zoonotic diseases. And international networks that include public health, research, medical and veterinary laboratories working with zoonotic pathogens should be established and strengthened. Facing this challenging future, the long-term strategies for zoonotic diseases that may be affected by climate change is need for better prevention and control measures in susceptible livestock, wildlife and vectors in Korea. In conclusion, strengthening global, regional and national early warning systems is extremely important, as are coordinated research programmes and subsequent prevention and control measures, and need for the global surveillance network essential for early detection of zoonotic diseases.

• Journal of Welding and Joining
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• 제29권1호
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• pp.80-84
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• 2011

The weight reduction of the transportations has become an important technical subject Al and Al alloys, especially Al 5052 alloys have been being applied as door materials for automobile. One of the most widely known car weight-reduction methods is to use light and corrosion-resistant aluminum alloys. However, because of high electrical and thermal conductivity and a low melting point, it is difficult to obtain good weld quality when working with the aluminum alloys. Also, Pulse MIG welding is the typical aluminum welding process, but it is difficult to apply to the thin plate, because of melt-through and humping-bead. In order to enhance weld quality, welding parameters should be considered in optimizing the welding process. In this experiment, Al 5052 sheets were used as specimens, and these materials were welded by adopting new Cold Metal Transfer (CMT) pulse process. The proper welding conditions such as welding current, welding speed, torch angle $50^{\circ}$ and gap 0~1mm are determined by tensile test and bead shape. Through this study, range of welding current are confirmed from 100A to 120A. And, the range of welding speed is confirmed from 1.2m/min to 1.5m/min.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.683-688
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• 2013

Candidate coating materials for re-usable metallic nuclear fuel crucibles, TaC, TiC, ZrC, $ZrO_2$, and $Y_2O_3$, were plasmasprayed onto a niobium substrate. The microstructure of the plasma-sprayed coatings and thermal cycling behavior were characterized, and U-Zr melt interaction studies were carried out. The TaC and $Y_2O_3$ coating layers had a uniform thickness, and high density with only a few small closed pores showing good consolidation, while the ZrC, TiC, and $ZrO_2$ coatings were not well consolidated with a considerable amount of porosity. Thermal cycling tests showed that the adhesion of the TiC, ZrC, and $ZrO_2$ coating layers with niobium was relatively weak compared to the TaC and $Y_2O_3$ coatings. The TaC and $Y_2O_3$ coatings had better cycling characteristics with no interconnected cracks. In the interaction studies, ZrC and $ZrO_2$ coated rods showed significant degradations after exposure to U-10 wt.% Zr melt at $1600^{\circ}C$ for 15 min., but TaC, TiC, and $Y_2O_3$ coatings showed good compatibility with U-Zr melt.

• 한국재료학회지
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• 제12권3호
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• pp.182-189
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• 2002

The Zr-0.2Sn-0.8Nb-X(X = 0~200ppm Si, 0~0.4wt.% Mo and Mn respectively) ingots for test specimens were manufactured by a vacuum arc re-melting method to find out the effect of Si, Mo, and Mn on the corrosion characteristics of the Zr-0.2Sn-0.8Nb alloy. After being heat-treated and rolled repeatedly out to be flat materials, they were finally heat-treated at 51$0^{\circ}C$ for three hours and used as the specimens for corrosion tests. The corrosion behavior of the specimens was studied in both 40$0^{\circ}C$ steam for 200 days and in aqueous 70 ppm LiOH solution at 36$0^{\circ}C$ for 90 days. From the study it was found that Si from 80 to 200 ppm contributed to increasing the corrosion resistance of Zr-0.2Sn-0.8Nb alloy in both steam and LiOH solution. This study also showed that Mn from 0.1 to 0.4% caused to go up the corrosion resistance, whereas Mo played a apart in improving the corrosion resistance only between 0.05 and 0.2 wt.%.

• 대한기계학회논문집B
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• 제35권11호
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• pp.1177-1184
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• 2011

GTS 기술은 천연가스 하이드레이트 생산, 해양수송 및 재기화의 3 단계로 구성되며, 대규모 재기화 플랜트의 효율적 운용을 위해서는 하이드레이트 펠릿의 재기화에 필요한 열수 온도와 유량의 정확한 예측이 필수적이다. 하이드레이트 펠릿이 열수에서 해리할 때 펠릿 표면에서 분출되는 가스는 주변 유동장과 열전달 특성에 영향을 미칠 것이며 본 실험에서는 가압된 용기내의 중저온 열수에서 해리하는 메탄가스 하이드레이트 펠릿의 용해특성을 연구하였다. 해리과정 중 변화하는 펠릿 형상을 관찰하고 해리 완료시간을 측정함으로써 하이드레이트 전환율, 열수 온도 및 유동속도가 해리에 미치는 영향을 파악하였으며, 펠릿 표면에서 분출되어 상승하는 메탄가스 기포류가 유발한 2 차유동이 열전달률을 증가시켜 해리 완료시간이 단축됨을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1765-1772
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• 2006

High-pressure die casting such as thixocasting and rheocasting is an effective process in the manufacturing automotive parts. Following the recent trend in the automotive manufacturing technologies, the product design subject to the die casting becomes more and more complex. Simultaneously the injection speed is also designed to be very high to establish a short cycletime. Thus, the requirement of the die design becomes more demanding than ever before. In some cases the product's shape can have multiple slender manifolds. In such cases, design of the inlet and outlet parts of the die is very important in the whole manufacturing process. The main issues required for the qualified products are to attain gentle and uniform flow of the molten liquid within the passages of the die. To satisfy such issues, the inlet cylinder ('bed cylinder' in this paper) must be as large as possible and simultaneously the outlet opening at the end of each passage must be as small as possible. However these in turn obviously bring additional manufacturing costs caused by re-melting of the bed cylinder and increased power due to the small outlet-openings. The purpose of this paper is to develop effective simulation methods of calculation for fluid flows in multiple columns, which mimic the actual complex design, and to get some useful information which can give some contributions to the die-casting industry. We have used a commercial code CFX in the numerical simulation. The primary parameter involved is the size of the bed cylinder. We will show how the very small opening of the outlet can be treated with the aid of the porous model provided in the code. To check the validity of the numerical results we have also conducted a simple experiment by using water.

• Food Science and Biotechnology
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• 제17권4호
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• pp.705-712
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• 2008

Sweet potato starch was modified using Thermus aquaticus $\alpha$-1,4-glucanotransferase ($Ta{\alpha}GT$), and its structural and rheological properties were investigated. $Ta{\alpha}GT$-modified starch had a lower amylose level and molecular weight than raw starch. The chain length distribution showed an increased number of short and long branched chains and the formation of cycloamyloses. Compared with raw starch, $Ta{\alpha}GT$-modified starch displayed a lower gelatinization enthalpy and a wider melting temperature range. The X-ray diffraction of $Ta{\alpha}GT$-modified starch was a weak V-type pattern with distinct sharp peaks at 13 and $20^{\circ}$. Scanning electron micrographs of modified starch exhibited big holes on the surface and the loss of granular structure. The frequency sweep measurement revealed that the gel of $Ta{\alpha}GT$-modified starch was more rigid than raw starch gel. However, the structure of modified starch gel was destroyed by heating at $75^{\circ}C$, and a firm gel was re-formed by subsequent storage at $5^{\circ}C$, indicating thermoreversible property.

• 암석학회지
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• 제25권1호
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• pp.39-50
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• 2016

제주도 현무암에 산출되는 첨정석 페리도타이트 포획암에 $CO_2$-유체포유물이 포획되어 있다. 이 $CO_2$-유체포유물들은 규칙적인 결정면으로 둘러싸여 있으며 세립의 네오블라스트 결정에는 일차포유물로, 조립의 반상쇄성에는 이차포유물로 산출된다. 냉각/가열 실험에서 $CO_2$-유체포유물의 삼중점은 $-57.1^{\circ}C$(${\pm}0.9^{\circ}C$)로서 대체로 균질하다. 이는 이 $CO_2$-유체포유물들이 거의 순수하게 $CO_2$로 이루어져 있음을 의미한다. 그러나 균질화 온도는 $-39^{\circ}C$(${\rho}=1.12g/cm^{3)}$)에서 $23^{\circ}C$(${\rho}=0.82g/cm^{3)}$)로 넓은 범위에 걸쳐 나타나며, 이는 많은 유체포유물이 포획된 이후 재평형 되어졌음을 반영한다. 일차/이차포유물과 균질화온도 사이에 체계적인 차이는 없다. 가장 낮은 균질화온도(즉, 가장 높은 밀도)를 보이는 유체포유물에서 계산된 포획 압력은 ${\approx}0.9GPa$이다. 제주 페리도타이트와 $CO_2$-유체포유물의 조직적 특성과 낮은 균질화 온도는 $CO_2$-유체가 맨틀기원의 유체로서 상부 맨틀암석권에서 페리도타이트의 재결정화 작용 동안 존재하던 유체로 해석된다. $CO_2$-유체의 포획은 제주 페리도타이트의 진화과정에서 후기의 사건이며, 상부맨틀 암석권의 상부(천부)에서 일어났음을 지시하고 있다.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.618-625
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• 2018

외부환경에 노출된 콘크리트 구조물은 사용기간 동안 시간의 경과함에 따라 여러 가지 환경적, 화학적, 물리적 요인들이 콘크리트 내부로 서서히 침투 및 확산되면서 콘크리트 초기의 우수한 내구성능을 저하시켜, 열화발생으로 인한 성능저하의 규명과 유지관리에 대한 중요성이 크게 부각되고 있다. 특히, 해안에 근접한 콘크리트 구조물이 동결융해 작용을 받는 경우, 동결융해의 과정에서 콘크리트 조직이 팽창 수축을 반복하면서 콘크리트의 조직이 이완되고 이때, 해수에 존재하는 염화물이온이 콘크리트 내부에 침입하게 되면, 콘크리트 구조물의 철근부식으로 인한 열화를 가속화시키기 때문에 내륙 콘크리트 건축물에 비해 내구성능의 저하가 급속히 진행됨으로 특별한 주의가 필요하다. 본 연구에서는 해수에 접한 콘크리트 구조물의 내구성 확보를 위해 광물성 혼화재료를 혼입한 코팅용 고성능 모르타르의 개발을 목적으로 하고 있으며, 모르타르의 강도 및 내구 특성에 대한 실험적 연구가 진행 되었다. 모르타르에 광물성 혼화재료인 실리카퓸, 메타카올린, 초고분말 플라이애시를 혼입하였다. 혼입률은 실리카퓸과 메타카올린은 각각 3, 7, 10%로 혼입하였으며, 초고분말 플라이애시는 5, 10, 15, 20%로 혼입하여 실험을 진행하였다. 혼화재료 혼입을 통해 제작된 모르타르 시험편을 재령 1일과 28일에 정적 강도시험을 진행하였으며, 재령 28일에 염소이온 침투저항성 시험, 황산 저항성 시험, 염해 저항성 시험 등의 열화 촉진실험을 실시하여 내구 특성을 분석하였다. 촉진 염화물이온 확산 침투 시험 결과를 이용해 국내 콘크리트학회에서 제안하는 방법과 미국, 유럽의 방법으로 내구수명을 평가해 보았다. 메타카올린 혼입 시 모든 규정에서 우수한 내구 수명으로 평가 되었으며, 메타카올린 10%혼입 시 KCI를 기준으로 약 470년의 내구수명이 예측되었다.

• 한국산학기술학회논문지
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• 제15권6호
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• pp.3990-3996
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• 2014

나일론66/유리섬유 복합체의 경우 $300^{\circ}C$ 이상의 고온에서 사출가공 될 때 물성 저하가 일어날 수 있어, 재이용시 열이력에 대한 체계적인 연구가 필요하다. $305/290/273/268/265/260^{\circ}C$ 온도조건의 이축압출기(twin screw extruder)를 이용하여 나일론66/유리섬유 복합체의 압출시료를 압출횟수에 따라 제조하였다. 압출횟수에 따른 화학구조, 열적특성, 용융지수, 결정구조, 아이조드 충격강도 및 유변학적 특성을 FT-IR, 용융지수 측정기, DSC, TGA, XRD, Izod 시험기, 그리고 유변물성 측정기를 이용하여 분석하였다. 적외선분광 스펙트럼을 이용하여 확인한 결과 압출횟수에 따른 압출시편에서의 화학구조 변화는 확인되지 않았다. 압출횟수에 따라 분자량이 감소하는 것을 용융지수와 복소점도를 이용하여 확인하였다. 나일론66/유리섬유 복합체의 용융온도는 큰 변화가 없으나, 압출횟수 증가에 따라 분해온도가 $20^{\circ}C$ 정도까지 감소하는 것을 DSC와 TGA를 이용하여 확인하였다. 압출시편의 아이조드 충격강도는 압출횟수가 증가함에 따라 감소하였다. 또한 나일론66/유리섬유 복합체 압출시편의 G'-G" 곡선의 기울기나 형태가 변하지 않는 것으로부터 압출시편에 가교와 같은 구조변화가 크게 나타나지 않음을 알 수 있었다.