• Journal of Energy Engineering
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• v.2 no.2
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• pp.139-153
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• 1993

20세기 인류가 이룩한 물질문명의 화려한 발전은 물질의 과량소비 에너지의 과다소비 공해물질의 대량배출 등의 바탕 위에 이룩되었다는 것을 아무도 부인하지 못할 것이다. 이 기간 동안 인류의 삶의 질은 향상되었을지 모르나 물질 및 에너지 자원의 고갈 지구환경의 파괴 질병의 유발 등과 같은 풀기 어려운 숙제를 후손들에게 남겨놓게 되었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.1068-1071
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• 2002

In this study, first, we show that the furnace process which requires maintaining high temperature is effected grievously by the temperature of surrounding air. Second, an alternative which maintains the relatively constant temperature dispersion surrounding the furnace and at the same time has economical advantages will be proposed.

• 축산식품과학과 산업
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• v.12 no.1
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• pp.59-72
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• 2023

• Transactions of Materials Processing
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• v.28 no.6
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• pp.361-367
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• 2019

Microstructure evolution and tensile properties of Al-8mass%Mg alloy casting billet by biaxial alternative forging were investigated in this study. An alternative forging system tailored in this study was used to allow continuous strain accumulations on the alloy workpiece. A finite element (FE) simulation results revealed that the strain was mainly concentrated in the core and that the shear bands developed into a form with an X shape in the cross-section of workpiece after the alternative forging using octangular rod shaped dies. With increasing the forging passes, it was observed that the Al-8mass%Mg alloy workpieces were significantly deformed, and cracks began to form and propagate on the both ends of the forged workpieces after five passes at room temperature. In as-forged microstructures taken by microscopes, twins, clustering of dislocations, and fine subgrains were found. Tensile strengths of the forged specimens showed significant increases depending on the number of forging passes, and a trade-off relationship was observed between the elongation and strength. At room temperature and 100℃ the workpieces showed similar behaviors in microstructural evolution and tensile properties depending on forging passes, while the increase range in strength was reduced at 200℃.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.499-506
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• 2015

Global navigation satellite systems (GNSS) is operating widely in civil and military area. GNSS signals, however, can be easily interfered because its signal is vulnerable to jamming. Thus, a sort of backup or alternative system is needed in order that the navigation performance is assured to a certain degree in case of GNSS jamming. In order to suggest a series of backup or alternative system of regional navigation, in this paper, we introduced a high altitude long endurance unmanned aerial vehicle (HALE UAV) with pseudolites using inverted GPS and transceiver system. We simulated the positioning error of the regional navigation system using HALE UAV with inverted GPS or transceivers concepts. We estimated the position error of HALE UAV calculate user position errors based on the position error of HALE UAV and general pseudorange error.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.7
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• pp.685-693
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• 2013

The biodiesel used as an alternative fuel for diesel engines is well- known, however the price of the bio-diesel is still higher than conventional diesel oil (DO) by 10% to 15% depending on a kind of bio-oil and a country producing the bio-diesel. One of idea to reduce the price of bio-diesel is to use the pure bio-oil as fuel for marine diesel engines, because to use the pure bio-oil as fuel without the esteritification process can reduce the price of bio-fuel. At present time, some experts in some countries who have been carrying out experiments on the use of pure bio-oil produced from rape seeds, sunflower seeds... as fuel for marine diesel engines have achieved important results. In recent years, at Vietnam Maritime University we also have been using the pure palm oil and its blended fuel (Palm oil and DO) as fuel for marine diesel engines in laboratory and on board of ships. The blended fuel is a mixing fuel of the pure palm oil and diesel oil with content of pure palm oil by 5%, 10%, 15%, 20% and 35%. In this paper, we would like to present some results from our experiments to investigate the impacts of using the palm oil and its blended fuel on the important technical features of the fuel supply system of marine diesel engines such as the fuel supply amount for one cycle, fuel supplying pressure, ignition delay time and so on. The results from the research will be good fundamental parameters to support proper operation of marine diesel engines using bio-oil and blended fuels as alternative fuel in near future.

• Environmental Analysis Health and Toxicology
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• v.30
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• pp.7.1-7.7
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• 2015

Objectives The widely promising applications of graphene nanomaterials raise considerable concerns regarding their environmental and human health risk assessment. The aim of the current study was to evaluate the toxicity profiling of graphene family nanano-materials (GFNs) in alternative in vitro and in vivo toxicity testing models. Methods The GFNs used in this study are graphene nanoplatelets ([GNPs]-pristine, carboxylate [COOH] and amide [$NH_2$]) and graphene oxides (single layer [SLGO] and few layers [FLGO]). The human bronchial epithelial cells (Beas2B cells) as in vitro system and the nematode Caenorhabditis elegans as in vivo system were used to profile the toxicity response of GFNs. Cytotoxicity assays, colony formation assay for cellular toxicity and reproduction potentiality in C. elegans were used as end points to evaluate the GFNs' toxicity. Results In general, GNPs exhibited higher toxicity than GOs in Beas2B cells, and among the GNPs the order of toxicity was pristine > $NH_2$ > COOH. Although the order of toxicity of the GNPs was maintained in C. elegans reproductive toxicity, but GOs were found to be more toxic in the worms than GNPs. In both systems, SLGO exhibited profoundly greater dose dependency than FLGO. The possible reason of their differential toxicity lay in their distinctive physicochemical characteristics and agglomeration behavior in the exposure media. Conclusions The present study revealed that the toxicity of GFNs is dependent on the graphene nanomaterial's physical forms, surface functionalizations, number of layers, dose, time of exposure and obviously, on the alternative model systems used for toxicity assessment.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.37-44
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• 2016

Republic of Korea has established its performance-based navigation (PBN) implementation plan in 2010 for ensuring a smooth transition to PBN operations and relevant new flight procedures are being developed in accordance with the roadmap. Various Navigation aids (NAVAIDs) like global navigation satellite systems (GNSS), distance measuring equipment (DME), VHF omnidirectional range (VOR), inertial navigation system (INS) are used to support PBN procedures. Among them, GNSS would play a central role in PBN implementation. However, vulnerability of satellite navigation signals to artificial and natural interferences has been discovered and various alternative positioning, navigation and timing (APNT) technologies are under development in many countries. In this paper, we study whether continuous PBN operations can be achievable without GNSS signals. As a result, it shows that some of the domestic airports require the construction of APNT in the approach area.

• Korean Journal of Construction Engineering and Management
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• v.16 no.3
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• pp.3-10
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• 2015

Value engineering (VE) of the construction project is classified into design phase value engineering and construction phase value engineering. Design phase value engineering must apply to over 10 billion public construction projects by government law. Therefore, the design value engineering apply to actively in construction projects. In contrast, the construction value engineering apply to a limited certain construction project. The reason is that construction value engineering process can not reflect practical demands quality. The construction value engineering can implement to positive impact through the feasibility verification for constructability. In this research, we propose a method of construction value engineering that reflect the practical demands. This method is experts alternative evaluation of using by GFI-based. And, this study was applied to the practical cases to verify the applicability of the proposed method. As a result, proposed alternative evaluation method were analyzed highly efficient in terms of applying the process as well as the method compare to the conventional method.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.3
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• pp.482-488
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• 2011

Cadmium (Cd) is well known as a spermatotoxic and gonadotoxic heavy metal ion. This study was performed to assess the possible protective effect of Enerbalance on Cd-induced spermiotoxicity and testicular damage. The control group received isotonic saline; Cd group received Cd (2 mg/kg BW per day) orally; extract-treated groups were orally administrated with Enerbalance (50 mg and 100 mg/kg BW per day) and Cd for 10 days. Morphological changes of testicular tissue, sperm characteristics, oxidative/antioxidative parameters from testis, and serum sexual hormone level were determined. Enerbalance was significantely increased sperm amount in cauda epididymis without changes of ratio of epididymis/body weight and testis/body weight. Cd caused a marked decrease in epididymal sperm concentration and chemotactic sperm motility, testicular superoxide dismutase (SOD), catalase (CAT), Enerbalance was significantly ameliorated loss of epididymal sperm concentration, sperm chemotactic motility, antioxidative parameters, and male hormone whereas decreased abnormal architecture by testis damage. Enerbalance was successfully attenuated these adverse effects of Cd and offers a dose-dependent protection. Our study demonstrated that Enerbalance could proffer a measure of protection against Cd-induced testicular damage and spermiotoxicity by possibly reducing oxidative stress and increasing the antioxidant defense mechanism in mice.