In this study, we investigated the effects of diesel-palm oil biodiesel-ethanol blends on combustion and emission characteristics in a 4-cylinder common rail direct injection (CRDI) diesel engine at low idling operations. The engine speed and engine load was 750 rpm and 40 Nm, while the main and pilot injection timing was respectively fixed at 2 °CA before top dead center (BTDC) and 20 °CA BTDC. The experimental results showed that the cylinder pressure increased with the increasing of palm oil biodiesel ratio from 20% to 100%. In addition, the peak value of cylinder pressure increased by 4.35% compared with pure diesel fuel when 5 vol.% ethanol oil added to diesel oil. Because the palm oil biodiesel and ethanol are the oxygenated fuel, the oxygen content played an important role in improving combustion. Based on the high oxygen content of biodiesel and ethanol, their mixing with diesel fuel effectively reduced PM emissions but increased NOx slightly, while CO and HC had no significant changes.

In this study, the effect of various pilot injection timings on combustion and emission characteristics were investigated in a common-rail direct injection (CRDI) diesle engine fueled with diesel-ethanol blends. The engine speed and engine load were controlled at constant 1500rpm and 70Nm, respectively. The tested fuels were DE0 (pure diesel fuel), DE5 (5 vol.% ethanol blended with 95 vol.% diesel oil), DE10 (10 vol.% ethanol blended with 90 vol.% diesel oil) and DE15 (15 vol.% ethanol blended with 85 vol.% diesel oil). The main injection timing was fixed at 0°CA TDC (top dead center), while various pilot injection timings including 25°CA BTDC (before top dead center), 20°CA BTDC and 10°CA BTDC were selected as the experimental variable. The experimental results showed that various pilot injection timings had little effect on the peak value of cylinder pressure, but had great influence on the start of combustion. The peak value of heat release rate (HHR) increased with the increase of ethanol content. However, the peak value of HRR reduced as the pilot injection is delayed. The diesel fuel containing 10% ethanol had a highest peak value of combustion pressure compared with the others, while the pilot injection timing occurred at 25°CA BTDC. On the other hand, the exhaust emissions of DE10 was also the lowest compared with the others. In addition, with the increase of ethanol content in diesel the PM and NOx emissions reduced.

Deicing agent refers to the substance that melts snow by exothermic or endothermic chemical reaction after spraying on snow. It also has the function of reducing the freezing point to prevent freezing. However, the long-term use of deicing agent can cause some negative problems, such as pot hole, concrete corrosion, vehicle and steel bridge parts corrosion. At present, wet salt spray deicing is a cost-effective deicing method that is being widely used. Typical deicing agents are calcium chloride and sodium chloride. Deicing equipment is placed to similar or higher corrosive environment than coastal or marine environment due to direct contact to chloride in deicing operation. Therefore, the anti-corrosion control is very important for the maintenance of deicing equipment. In this study, corrosion resistance, blistering and repairability of the deicing equipment were tested by using test standard (salt water production and spraying- KS D 9502 , evaluating degree of rusting- ASTM D 610, evaluating degree of blistering- ASTM D 714, pull-off strangth of coatings- ASTM D 4541). And an economical coating system with long-term antirust performance was constructed. The results show that the performance of the coating system has been improved than with the original coating.

In this study, the shrinkage at the artificial skin tissue and temperature characteristics of rubber pole were analyzed by the experimental and numerical method. A artificial skin tissue was produced by using the rigid sponge pad. The impact of tissue was applied by three types of rubber pole. The shrinkage results along the depth of tissue were measured according to the repetition count of impact. When the shape of rubber pole was sphere type, the shrinkage was greatest. The temperature around the pole was highest in the sphere type while that inside pole was greatest in the twine deep sphere type. This is because the pole temperature of twine deep sphere type was transmitted more inside. As a result, the sphere type rubber pole was the most effective because it showed the largest shrinkage and the lowest temperature gradient during impact.

최근 관광, 레저 수요의 증대로 해안 시설물(방파제)에서 낚시를 통해 여가를 즐기는 낚시객의 증대와 아울러 매년 해안 시설물인 소파블록(Tetrapod, TTP)에서의 낙상사고가 사회적 문제가 되고 있다. 본 연구에서는 낙상사고가 주로 발생하는 소파블록을 안전망으로 덮어 낚시객의 낙상을 저감하는 안전사고 방지 시설물 개발의 기초 연구로서 적절한 그물코 크기를 제시하고자 한다. 이는 안전망 시설물의 규모 및 경제성을 고려할 때 반드시 선행되어야 할 부분이다. 본 연구에서 적용한 안전망의 그물코 크기 결정 방법은 낚시객들의 성별, 연령별 현황과 한국인의 인체치수조사 결과를 바탕으로 최적의 그물코 크기를 산정하고자 하였다. 그 최종 결과로서 안전망의 그물 코 크기는 최소 낚시객의 넙다리 둘레에서부터 최대 가슴둘레까지를 고려하여 18.6~27.0 cm의 범위로 산정되었다.

목적 : 청광 차단렌즈의 효과를 정량적으로 분석하는 방법을 새롭게 제시하고, 이를 시판하고 있는 기능성 렌즈에 적용하여 비교 분석함으로써 그 활용 가능성을 확인하고자 하였다. 방법 : 렌즈의 광투과율을 측정하고, 청광 차단 효율 함수를 적용하여 효율에 대한 정성적인 분석을 하였다. 또한 청광 차단 효율 결과를 적분하여 수치화하는 정량적인 분석 방법을 새롭게 도입하여, 시판중인 청색광차단 기능성 렌즈에 적용하여 비교분석하였다. 결과 : 정성적인 분석 방법을 일반렌즈, 코팅방법으로 제작된 2종의 렌즈와 착색방법으로 제작된 1종의 렌즈에 적용한 결과, 모든 렌즈는 단파장 영역의 빛을 차단하는 효과가 우수한 것으로 분석되었다. 하지만 정량적인 분석 방법에 의한 결과에서는 각 렌즈별 다소 차이가 있음을 확인하였다. 결론 : 다양해지는 디스플레이 장치 및 스마트폰의 광 특성이 날로 진화되고 변화되고 있으므로, 다양한 방법으로 광원과 광학제품에 대한 광특성 분석이 요구된다. 이에 따라, 본 연구에서 새롭게 도입한 정량적인 분석 방법이 효과적인 수단일 될 수 있는 가능성을 확인 하였다.

In this study, the thermal behavior characteristics of flange case interior were analyzed by the numerical method. The boundary conditions at the inlet port of flange case were the heat flux and heat flux time. As the heat flux time at inlet of case increased, the temperature values gradually increased, and the degree of increase was very small. If the heat flux of the melted iron increases to 2,000,000 W/m2, the temperature change at the case interior will occur largely, causing heat deformation. As a result, in order to reduce thermal defects at the case interior, the heat flux and heat flux time of the melted iron should be set within 500,000 W/m2 and 5 seconds, respectively.

In this study, the effect of carbon equivalent and cooling rate on microstructure and hardness of A516 steels for pressure vessel is investigated. Six kinds of specimens are fabricated by varying carbon equivalent and cooling rate, and their microstructures and hardness levels are analyzed. Specimens with low carbon equivalent consist of ferrite and pearlite. As the cooling rate increases, the size of pearlite decreases slightly. The specimens with high carbon equivalent and rapid cooling rates of 10 and 20 oC/s consist of not only ferrite and pearlite but also bainite structure, such as granular bainite, acicular ferrite, and bainite ferrite. As the cooling rate increases, the volume fractions of bainite structure increase and the effective grain size decreases. The effective grain sizes of granular bainite, acicular ferrite, and bainitic ferrite are ~20, ~5, and ~10 μm, respectively. In the specimens with bainite structure, the volume fractions of acicular ferrite and bainitic ferrite, with small effective grains, increase as cooling rate increases, and so the hardness increases significantly.

지적장애아동은 낮은 지적능력으로 인해 주의집중력의 지속시간이 짧으며 정상적인 언어습득과 발달이 어렵다. 그러므로 사회성이 떨어지고 사람과의 유대감을 형성하는 것이 어려울 수 있다. 지적장애아동의 특성을 효과적으로 개선하는 방법에는 동물을 통한 매개 활동이 있다. 동물은 아동과의 상호작용을 통하여 언어능력을 향상 시키고, 인지발달을 촉진시킨다. 그리고 의사소통이나 상호작용이 미숙한 아동에게 동물매개활동은 의사소통 및 자기표현 기술을 습득하는 데 유용하게 작용할 수 있다. 본 연구는 동물매개활동 프로그 램이 지적장애아동의 주의집중력과 언어능력에 미치는 효과를 알아보기 위해 J도 I시 특수 장애 학교에 다니고 있는 만 14세에서 16세인 지적장애아동 3명을 대상자로 선정하였다. 연구는 주 1회, 8주간, 총 16회기 동안 진행하였다. 사전ㆍ사후 검사 도구로는 Harris & Harris(1984)의 집중력 격자판 검사와 수용·표현 어휘력 검사(Receptive and Expressive Vocabulary Test: REVT)를 이용하여 연구 대상자들의 주의집중력과 수용·표현 어휘력의 비교분석을 하였다. 이 연구를 통해 동물매개활동 프로그램이 지적장애아동의 주의집중력과 수용·표현 어휘력을 유의미한 수준으로 향상시켜 주었음을 관찰할 수 있었다.