• 한국통신학회논문지
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• 제33권6B호
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• pp.430-439
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• 2008

본 논문에서는 셀룰러 망에서 무선 LAN으로 핸드오버를 수행하는 하향 수직 핸드오버 상황에서 TCP의 처리량 저하 문제를 해결하기 위한 송신자 기반의 새로운 혼잡 제어 기법을 제안한다. TCP는 하향 수직 핸드오버와 같이 링크의 특성이 급격히 변하게 되는 상황에 쉽게 적응하지 못하고 처리량이 저하되는 문제가 발생한다. 이 문제의 주된 원인은 셀룰러 망과 무선 LAN의 지연 시간 차이에 의해 생기는 패킷 재정렬에 의한 것으로, TCP는 이로 인해 필요하지 않은 혼잡 제어를 수행한다. 그 결과 TCP의 혼잡 윈도우의 크기가 줄어드는 것은 물론 무선 LAN의 대역폭마저 낭비된다. 본 논문에서는 이러한 현상을 방지하기 위해 송신자 측에서 하향 수직 핸드오버 발생 전까지 측정하던 셀룰러 망의 왕복 시간을 이용하여 재정렬로 인해 발생하는 중복된 ACK를 처리하는 한편, 중복된 ACK를 활용하여 TCP의 혼잡 윈도우 크기를 조절을 통해 TCP의 처리량을 향상 시키는 기법을 제안한다. 시뮬레이션을 통해 본 논문에서 제안한 기법이 하향 수직 핸드오버 수행 시 발생하는 재정렬에 의한 문제를 해결하고, TCP New Reno 및 기존에 제안되어 있는 nodupack 방식에 비해 처리량을 향상시킴을 보인다.

• Mycobiology
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• 제43권4호
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• pp.423-434
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• 2015

The study was conducted to compare the effects of different agro-wastes on the growth, yield, and nutritional composition of oyster mushrooms Pleurotus ostreatus (PO) and Pleurotus cystidiosus (PC). Seven substrate formulas including sawdust (SD), corncob (CC), sugarcane bagasse (SB) alone and in combination of 80 : 20, 50 : 50 ratio between SD and CC, SD and SB were investigated. The results indicated that different substrate formulas gave a significant difference in total colonization period, characteristics of fruiting bodies, yield, biological efficiency (BE), nutritional composition and mineral contents of two oyster mushrooms PO and PC. The results showed that increasing CC and SB reduced C/N ratio, and enhanced some mineral contents (Ca, P, and Mg) of substrate formulas. The increased amount of CC and SB of substrate formulas enhanced protein, ash, mineral contents (Ca, K, Mg, Mn, and Zn) of fruiting bodies of both mushrooms. Substrates with 100% CC and 100% SB were the most suitable substrate formulas for cultivation of oyster mushrooms PO and PC in which they gave the highest values of cap diameter, stipe thickness, mushroom weight, yield, BE, protein, fiber, ash, mineral content (Ca, K, and Mg) and short stipe length. However, substrate formula 100% CC gave the slowest time for the first harvest of both mushrooms PO and PC (46.02 days and 64.24 days, respectively). It is also found that the C/N ratio of substrate formulas has close correlation with total colonization period, mushroom weight, yield, BE and protein content of mushroom PO and PC.

• 한국지반공학회지:지반
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• 제13권1호
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• pp.59-74
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• 1997

본 논문에는 사용종료된 쓰레기 매립장의 건설부지로의 개발가능성을 알아 보기 위하여 지반 조사와 침하해석을 수행한 결과를 나타내었다. 쓰레기 폐기물의 침하특성을 저감하고 강도특성을 향상하기 위하여 생석회와 시멘트 계통 그라우트재를 혼합 그 특성변화를 분석하였으며 대상 약액으로는 생석회, 보통시멘트, 슬래그시멘트, Geocrete시멘트의 4종류가 사용되었다. 현장지반조사 결과 쓰레기의 매립기간이 짧아 유기질 함량이 큰 쓰레기가 매립기간이 긴 쓰레기에 비교하여 최적함수비는 크고 최대건조밀도가 작은 것으로 나타났다. 매립쓰레기의 두께가 지점별로 큰 차이를 보였으며 침하량 분석 결과 위치에 따른 침하량의 차이가 크게 나타났다. 고결공법의 적용성을 검토한 결과 쓰레기 강도의 향상정도는 Geocrete시멘트, 슬래그시멘트, 보통 포틀랜드시멘트, 생석회의 순으로 우수한 것으로 나타났다.

• 한국환경보건학회지
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• 제19권3호
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• pp.1-16
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• 1993

This paper describes an investigation to determine whether the activated sludge (AS) process could be used for the treatment of wastewater at the Union Carbide Coporation (UCC) plant in Seadrift, Texas. This plant presently utilizes a waste stabilization pond (WSP) system for treatment of the wastewater. The treatment system consists of an in-plant primary WSP and two off-plant WSPs (secondary and tertiary WSPs), run in series. The total hydraulic detention time of the WSP system is approximately 150 days. Several laboratory-based treatability studies have been conducted to evaluate the performace of the WSP system and the degradability of specific chemical compounds. From an additional study, it was determined that the WSP system was stressed and occasionally operating near the limit of its treatment capacity. The existing primary WSP plays an important role in the overall treatmemt system, because it not only functions as a pH and organic-strength equalization basin, but also serves as a "preconditioning" basin by fermenting high strength organic wastes to volatile organic acids for subsequent degradation in the escondary WSP. However, in view of pending RCRA legislatin conerning the "proposed organic toxicity characteristics limits" (40 CFR Part261: Federal Register, July, 1988), it is possible that the primary WSP will have to be abandoned in favor of alternative treatment options. Therefore the main purpose of this study was to perform activated sludge treatability evaluations for the development of an alternative to the existing primary WSP treatment ststem. In addition, another purpose was to determine the degradability of bis(2-chloroethyl)ether (Chlorex or CX) and benzene(BZ) in the activated sludge process. The presence of these two chemicals in the wastewater of the plant prompted the question of whatedether they could be degraded in an activated sludge system.

• 한국환경보건학회지
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• 제35권3호
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• pp.226-234
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• 2009

The main objective of this study was to evaluate the effects on shape and size, compressive strength, water absorption and heavy metals leaching with various weight mixing ratios in waste ash brick products using waste recycling MSWI(Municipal Solid Waste Incinerator) bottom ash, steel slag and waste building material. The manufacturing processes for the waste ash brick consist of screening, mixing, conveyor transmission, compaction.forming, and curing steps of raw materials. The weight mixing ratios of steel slag around bottom ash were adjusted within the ranges of 10% to 30%. The reported results show that the width and thickness of the manufactured waste ash brick could be satisfied with $90{\pm}2mm\;and\;57{\pm}2mm$, respectively which are K.S. standards of products qualities. And in case of length, only 20-Ba50Ss30, 20-Ba60Wb20 and 20-Ba50Wb30 for the mixing ratios could be satisfied with $190{\pm}2mm$ that is K.S. standards of products quality. The compressive strength and water absorption for 20-Ba50Ss30 and 20-Ba70Wb10 were over $8N/mm^2$ and below 15% respectively that are K.S. standards of manufactured waste ash brick. The results of tests for the heavy metals leaching in the all manufactured waste ash bricks are also passed to the wastes management regulations. The cost analysis of 20-Ba50Ss30 is evaluated. The manufacturing cost is evaluated 34.3 won/brick with 8 hours and 20tons of raw material per day. Incinerators with problems in bottom ash disposal can therefore derive significant benefits from the application of waste ash brick production.

• 자원리싸이클링
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• 제14권6호
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• pp.37-43
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• 2005

페리튬이온전지로부터 회수된 코발트와 리튬 침출액으로부터 화염분부열분해법에 의하여 $LiCoO_{2}$ 나노분말을 제조하였다. 리튬 및 코발트 성분을 함유하는 전극물질은 열처리 및 기계적 처리에 의해 그 농도를 증가 시켰다. 리튬이온전지 양극물질을 질산으로 용해한 다음 침출액중 Li과 Co의 당량비가 1.0 되도록 $LiNO_{3}$로 조절하여 화염분무열분해용 전구체를 제조하었다. 화염분무열분해법에 의해 제조된 $LiCoO_{2}$ 분말의 평균입자크기는 전구체의 몰 농도가 증가하면서 증가되었으며, 화염온도 역시 입자의 크기를 증가시켰다. 변수실험 결과 $11{\~}35nm$ 크기의 결정형 $LiCoO_{2}$ 나노분말을 제조할 수 있었다 또한 나노 $LiCoO_{2}$의 전극재료로서의 가능성을 확인하기 위하여 충방전 특성 평가와 같은 전기화학적 분석을 수행하였다.

• 지질공학
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• 제16권4호
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• pp.351-357
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• 2006

상수원으로 사용하고 있는 주요 하천으로의 위해물질의 유입은 정수장에서의 고도기술을 요구하게 된다. 그러므로 산업폐수로부터 방류되는 이들 미량유해화학물질의 모니터링을 적절하게 하는 것은 위해도 저감 뿐 만 아니라 하천관리의 경제성도 증가시킬 수 있다. 본 연구를 통해 모니터링 한 여러 미량 유해화학물질 중에서 산업폐수의 방류수에서 검출된 오염물질 중 가장 주요한 항목은 Hexachlorobutadiene 였다. 그러나 반도체, 전기/전자 및 금속조립 산업폐수로 구성된 Group II에서는 모든 항목이 불검출로 나타났다. 따라서 향후 상수원 수질개선 및 보호를 하기 위해 모니터링 항목을 선정하는데 있어서는 해당 수계로 부하되는 물질들의 특성과 거동을 제대로 파악하기 위한 사전모니터링을 실시하여 시간, 노력 및 경제적인 손실을 최소화하여 효율적인 상수원관리를 해야 한다.

• 환경영향평가
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• 제11권1호
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• pp.25-36
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• 2002

The purpose of this study is to assess the environmental carrying capacity of Chongju City for the environmental management and the urban growth management. The urban environmental carrying capacity assessment of the city by the index of ecological footprint(EF), shows that the ecosystem of the city has been overloaded and most of the deficiencies has come from outside of the city. The EF index, the area of land per capita required for production and consumption in the city, was 1.731 ha per capita in 1989 and 1.901 ha per capita in 1999. On the other side, the ecologically productive land is 0.0175 ha per capita. It means that every citizen owes 1.88 ha per capita to the ecosystem in 1999. The land consumption of the city has increased by 0.1705 ha per capita during the last 10 years. The capacity of infrastructure and the service supply estimated by the Onishi model does not exceed the demand of the city in 1999. But the rapidly increasing population and fast urban growth need the expansion of the capacity. The water supply capacity of the city appears to be sufficient in 1999, but the water supply demand will increase in the future. The capacity of sewage treatment facilities seems to be sufficient, but the higher level of sewage treatment facilities should be adopted for the improvement of water quality as the generation of sewage will increase and its characteristics will also make the wastewater treatment difficult. Due to the decrease of solid waste generated, the land fill capacity for solid waste disposal is not insufficient at present, but the capacity will be saturated in the near future. Therefore, the scientific management system of solid wastes should be introduced. The air quality of the city meets both the national air quality standard and WHO recommendation standard, but the strong regulation and control of automobile emission gas such as CO, $CO_2$, NOx and HC is required for clean air.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.48-56
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• 2014

Engine oil is an oil used for lubrication of various internal combustion engines. The main function is to reduce wear on moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts. In engines, there are parts which move against each other. Otherwise, the friction wastes the useful power by converting the kinetic energy to heat. Those parts were worn away, which could lead to lower efficiency and degradation of the engine. It increases fuel consumption, decreases power output, and can induce the engine failure. This study was conducted to evaluate the relation between engine oil property changes and engine performance for the diesel engine. This test was performed by using 12L, 6 cylinder, heavy duty engines. Low SAPS 10W30 engine oil (two type engine oils) was used. Test procedure and method was in accordance with the modified CEC L-57-T97 (OM441LA) method. In this study, TAN, TBN, KV and metal components, engine power, blowby gas, A_F were presented to evaluate the relation with engine oil property changes and engine performance. TAN, TBN, KV and metal We found that the components were generally increased but engine performance did not change. This results mean that property changes did not affect on engine performance because those were not enough to affect engine performance.

• 자원리싸이클링
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• 제25권1호
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• pp.31-39
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• 2016

전기밥솥, 청소기, 선풍기 등 폐소형가전 기기들은 종류 및 품목에 따라 내부 구성 물질과 플라스틱 재질이 다양하기 때문에 해체 및 선별에 특정기술의 적용이 어려운 실정이다. 본 연구에서는 폐소형가전 제품 중 재활용 업체에서 비교적 취급양이 많은 품목 중, 전기밥솥 등 5개 품목을 대상으로 수작업으로 해체 후 물리적 성상을 분석하였다. 또한, 폐소형가전은 대형가전제품에 비해 플라스틱의 함량이 비교적 높을 뿐만 아니라 재질이 다양하여, 재질별 선별이 어려워 플라스틱의 재활용에 걸림돌이 되고 있다. 특히, 폐소형가전의 경우 검정색 플라스틱의 비율이 상대적으로 높아 재질 선별이 제대로 이루어지지 못하여, 혼합물의 형태로 저급 재활용되고 있다. 본 연구에서는 중액선별, 정전선별 그리고 근적외선 선별 등 기존의 선별 기술을 적용하여 검정색 플라스틱에 대한 재질 선별 가능성을 검토하였으며, 각 기술에 대한 문제점 및 제한사항을 제시하였다.