• 청정기술
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• 제17권3호
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• pp.191-200
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• 2011

재생 가능한 자원으로 만들어지는 천연고분자, 바이오 고분자 및 합성고분자들은 지속가능하며 환경 친화적인 플라스틱으로 21세기 화두가 되고 있으나 많은 양의 썩지 않는 석유화학 유래 플라스틱이 사용되고 있다. 최근 들어 세 가지 관점에서 생분해성 고분자들이 많은 관심을 받고 있다: 1. 채취하기 쉬운 자원의 고갈에 따른 석유제품의 가격상승, 2. 폐플라스틱에 대한 환경 및 경제적인 관심, 3. 석유화학 유래 재료의 제조에 따른 이산화탄소배출. 이러한 관점에서 제조공정상에서 이산화탄소를 저감할 수 있는 poly(hydroxy alkanoate)나 poly(lactide)와 같은 생분해성 고분자에 대한 상업적 응용에 대한 관심이 고조되고 있다. 이들 고분자들은 초기분해가 진행됨에 따라 급격히 기계적 물성을 상실하기 때문에 상업적 응용을 위하여서는 분해거동이 중요하다. 본 총설에서는 초기분해속도의 조절을 위한 고분자 개질에 대한 최근의 연구동향을 살펴보았다.

• 한국환경과학회지
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• 제13권10호
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• pp.911-919
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• 2004

The purpose of this research was evaluated economical effect to apply alternative external carbon source. Conventional activated sludge process in municipal wastewater treatment plant was adapted and introduced to Biological nutrient removal processes to meet the newly enforced effluent quality standard for nutrient removal in Korea. Low $COD/NH_4^+-N$ ratio and higher nutrient concentration of influent characteristics force to inject external carbon source for denitrifying recycled nitrate. In the most case, methanol was used as external carbon source. But Methanol is expensive and very dangerous in handling. So we could find cheaper and safer external carbon source substituted methanol in last study. This alternative external carbon source is named RCS(recoverd carbon source) and a by-product of fine chemical product at chemical plant. When RCS was applied real municipal wastewater treatment plant, average $55\~65\%$ of T-N removal efficiency, 8.8mg/l of effluent T-N concentration, 11.3mg/l of effleunt COD concentration were obtained without effluent COD increase as against used methanol. To apply RCS in municipal wastewater treatment plant obtain approximately $\74.5%$ expenditure cost reduction in comparison with methanol dosage cost.

• Journal of Radiation Protection and Research
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• 제42권3호
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• pp.141-145
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• 2017

Background: The concrete walls inside the vaults of cyclotron facilities are activated by neutrons emitted by the targets during radioisotope production. Reducing the amount of radioactive waste created in such facilities is very important in case they are decommissioned. Thus, we proposed a strategy of reducing the neutron activation of the concrete walls in cyclotrons during operation. Materials and Methods: A polyethylene plate and B-doped Al sheet (30 wt% of B and 2.5 mm in thickness) were placed in front of the wall in the cyclotron room of a radioisotope production facility for pharmaceutical use. The target was Xe gas, and a Cu block was utilized for proton dumping. The irradiation time, proton energy, and beam current were 8 hours, 30 MeV, and $125{\mu}A$, respectively. To determine a suitable thickness for the polyethylene plate set in front of the B-doped Al sheet, the neutron-reducing effects achieved by inserting such sheets at several depths within polyethylene plate stacks were evaluated. The neutron fluence was monitored using an activation detector and 20-g on de Au foil samples with and without 0.5-mm-thick Cd foil. Each Au foil sample was pasted onto the center of a polyethylene plate and B-doped Al sheet, and the absolute activity of one Au foil sample was measured as a standard using a Ge detector. The resulting relative activities were obtained by calculating the ratio of the photostimulated luminescence of each foil sample to that of the standard Au foil. Results and Discussion: When the combination of a 4-cm-thick polyethylene plate and B-doped Al sheet was employed, the thermal neutron rate was reduced by 78%. Conclusion: The combination of a 4-cm-thick polyethylene plate and B-doped Al sheet effectively reduced the neutron activation of the investigated concrete wall.

• 대한토목학회논문집
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• 제11권2호
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• pp.99-105
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• 1991

본 연구는 도시폐기물의 성상을 이용하여 에너지회수공정 선택을 위한 기초자료를 얻고자 수행되었다. 폐기물은 서울시 강동구 지역에서 채취하여 물리적조성과 화학적조성이 조사되었으며, 혐기성소화실험을 통해 폐기물내의 생물학적 분해불능물질함량을 결정하였다. 분석결과에 의하면 폐기물의 탄소함량, 수소함량 및 저위발열량은 다음식에 의해 계산되어질 수 있었다; C=0.57VS, H=0.084 VS, HI=49.5VS-(6-0.045 VS)W. 또한 폐기물내의 생물학적 분해불능물질함량은 가연성물질의 58.9%, 전체폐기물의 77.7%로 나타났다. 폐기물의 처리공정중 무게감량이 가장 큰 것은 소각이며 에너지생산량은 연료생산이 가장 큰 것으로 나타났으나 에너지회수공정의 결정시는 폐기물의 연중 발열량변화, 매립지 확보문제 및 추가환경오염여부등의 제반조건이 충분히 고려되어져야 할 것이다.

• Advances in concrete construction
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• 제4권2호
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• pp.123-143
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• 2016

Use of heavy fuel fly ash (HFFA) (diesel and cracked fuel) for power generation in Saudi Arabia has generated and accumulated large quantities of HFFA as a byproduct. In this research, HFFA is studied with the emphasis on the utilization of this waste material in concrete blocks and asphalt concrete mixes. Two types of mixes, one with low and other with high cement content, were studied for concrete blocks. Different mixes having varying percentages of HFFA (0% to 25%), as cement/sand replacement or as an additive, were studied. The performance of concrete blocks is evaluated in terms of compressive strength, water absorption, durability and environmental concerns. The results showed that blocks cannot be cast if more than 15% HFFA is used; also there is a marginal reduction in the strength of all the mixes before and after being exposed to the sulfate solution for a period of ten months. HFFA is studied in asphalt concrete mixes in two ways, as an asphalt modifier (3&5%) and as a filler (50%) replacement, the results showed an improvement in stiffness and fatigue life of mixes. However, the stability and indirect tensile strength loss were found to be high as compared to the control mix due to moisture damage, indicating a need of using antistripping agents. On environmental concerns, it was found that most of the concerned elements are within acceptable limits also it is observed that lower concentration of barium is leached out with the higher HFFA concentrations, which indicates that HFFA may work as an adsorbent for this leaching element.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.459-465
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• 2007

This study was conducted to calculate the LCC of a apartment complex with a type of heating system, district heating and cogeneration system. For the purpose of analyzing LCC according to size of apartment complex, 500, 1,500 and 4,000 houses of model apartment selected. This research performs design of heating system and the life cycle cost analysis including an initial cost, energy cost, maintenance and operation cost, replacement cost and renovation cost during the project period(15years). According to the calculated results, 1) Initial cost of cogeneration system with 500, 1500 and 4000 houses is higher than district heating system each of 20%, 13%, 12%. 2) In case of cogeneration system, the payback period by electric generation is 5.21, 4.92 and 4.47 years and saving cost was calculated 29 billion won, 94 billion won and 262 billion won after payback period. 3) Cogeneration system LCC was 1.12, 1.07 and 1.06 times larger than district system with the size of apartment complex. According to the case of this study district heating system is more efficient than cogeneration system in terms of the reduction of LCC. 4) Gas Engine Co-generation System is more efficient than other systems because it can collect progressive part from electric charge progressive stage system. However, the efficiency is decreasing because of raising of fuel bills(LNG) and lowering of power rate for house use. Especially the engine is foreign-made so the cost of maintenance and repair is high and the technical expert is short. 5) District heating is also affected by fuel bills so we should improve energy efficiency through recovering of waste heat(incineration heat, etc.). Also, we should supply district cooling on the pattern of heat using of let the temperature high in winter and low in summer.

• 설비공학논문집
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• 제29권5호
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• pp.239-248
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• 2017

At the $21^{st}$ Conference of the Parties (COP) of the United Nations Climate change Conference, representatives of the 195 member countries reached an agreement requiring all participating countries, including Korea, to establish proactive measures to fight climate change. Under this vision, energy network technologies are deemed as a key site of research towards meeting this goal. Herein, the headquarters of the Korea Institute of Energy Research (KIER) is a worthy site for carrying out energy network technology research insofar as it contains various heat sources. To prepare for this research, a study was conducted analyzing the heat sources at KIER based on measured data. The study also consisted of developeding simulation models to predict the amount of energy savings that could be derived by replacing an absorption chiller/heater with an absorption heat pump during winter seasons. In our simulation results, we observed a primary energy saving ratio of 65~72% based on the water temperature from the heat source of a coal power plant.

• 대한조선학회논문집
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• 제55권5호
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• pp.448-455
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• 2018

Glass wool is an eco-friendly materials that is manufactured through a continuous process by processing waste glass. This materials is low cost compared with another materials and has excellent thermal conductivity. For this reason, glass wool is installed as insulation system for LNG carriers and as insulation of building wall as well as various industries. The mechanism of insulation of glass wool is the conduction of the wool itself and convection by space between fibers. Therefore, in order to develop the enhanced thermal conductivity of glass wool is necessary to reduce its own conduction or to insert additional material after manufacturing as well as prevent convection. In this respect, many researchers have been actively studying to decrease thermal conductivity of polyurethane foam using by inserted glass wool or change the chemical component of glass wool. However, many research are aiming reduction of glass wool itself. This study focus on post-processing and inserted different materials; silica-aerogel, kevlar fiber 1mm, 6mm and glass bubble. Experimental results show that the thermal conductivity almost decreases with the addiction of glass bubble and silica aerogel.

• 설비공학논문집
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• 제27권10호
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• pp.544-551
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• 2015

This study was conducted to determine the LCC of apartment complexes with district heating and a cogeneration system. For the purpose of analyzing LCC according to the size of the apartment complex, 500, 1,500, and 4,000-unit model apartments were selected. Analysis was performed on the design of the heating system and the life cycle cost including total construction cost, maintenance and operation cost for the duration of the project period (15 years). According to the calculated results, 1) The initial cost of the cogeneration system for 500, 1,500, and 4,000-unit apartments is higher than that of the district heating system by 20%, 13%, and 12%, respectively. 2) In the case of the cogeneration system, the payback period by electric generation was found to be 5.21, 4.92 and 4.47 years, and saving cost was calculated to be 29 billion won, 94 billion won and 262 billion won after the payback period for 500, 1,500, and 4,000-unit apartments, respectively. 3) The LCC values of the cogeneration system were 1.12, 1.07 and 1.06 times larger than those of the district system according to the size of the apartment complex. In this study, the district heating system was found to be more efficient than the cogeneration system in terms of LCC reduction. 4) District heating is affected by fuel bills, so energy efficiency should be improved through recovering waste heat (incineration heat, etc.). Also, district cooling should be provided according to heat use to keep the temperature high in winter and low in summer.

• 한국건설관리학회논문집
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• 제4권1호
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• pp.90-96
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• 2003

도심지 건축공사가 증가하고 있는 우리나라에서 작업공간의 부족 및 자재의 적시공급에 대한 문제는 반드시 해결해야 할 과제이다. 이 중에서도 주택건설에 있어 가장 큰 비중을 차지하고 있는 아파트 시공의 경우, 초고층화로 골조공사의 중요성과 함께 친환경적 공법과 합리적 공정개선 및 원가절감을 구현할 새로운 공법이 요구되고 있다. 본 연구에서는 국내 건설현장의 사례조사를 통해 슬래브 거푸집공사와 마감공사의 프로세스에서 불필요한 요소를 최소화하고자 공업화 자재를 활용한 (골조-마감공사)통합공법을 제시한다 가치흐름분석기법(Value Stream Mapping)을 활용하여 기존 프로세스에서의 비 가치 창출작업을 가치창출작업에 통합시키거나 제거하여 슬래브 공사 내에서 공기 및 투입인력의 절감 가능성을 확인하고, 공기단축과 원가절감 효과를 측정하였다. 이와 같이 공업화 자재의 활용으로 현장작업에 따른 변이를 최소화하여 공정의 안정성 및 공정계획의 신뢰성을 확보 등 공정의 합리화를 구현하고자 한다.