• 한국ITS학회 논문지
• /
• 제3권2호
• /
• pp.55-68
• /
• 2004

본 연구에서는 고속도로 교통정보의 적정 가치를 산정하고자 비 시장재의 가치 추정에 많이 적용되고 있으며 환경경제학 분야에서 발전되어온 조건부 가치측정법을 사용하였다. 비 시장재인 고속도로 교통정보의 적정한 가치를 추정하기 위하여 가상 시나리오를 설계하고 설문의 신뢰도를 높이기 위하여 교통관련 분야의 전공자를 설문자로 하였으며 일대일 면접을 실시하였다. 또한 질문 방법으로 개방형 질문과 지불카드 방법을 혼용하여 사용하였다. 교통정보의 가치추정식으로 다중회귀 모형을 사용하여 교통정보의 가치에 영향을 미치는 정도를 알아보았다. 연구결과 정보별 1회 이용시 지불하고자 하는 가격은 현재 제공되는 가격보다 다소 비싼 가격을 지불할 의사를 보였으나 전체적인 가격을 묻는 월정액은 낮게 지불의사를 표시하였다. 이는 개별적인 정보에 대한 가치나 유용성은 수긍하나 공공의 정보는 무료로 제공되어야 한다는 다수 이용객들의 인식이 지불 의사를 낮게 표시한 것으로 판단된다.

• 농촌지도와개발
• /
• 제20권4호
• /
• pp.1149-1179
• /
• 2013

본 연구에서는 농촌노인들의 일자리사업 참여실태와 만족도 및 요구도를 살펴봄으로써 농촌노인들의 삶의 질 향상에 필요한 기초자료를 제공하고자 하였다. 본 연구의 결과는 다음과 같다. 첫째, 농촌노인들은 노인일자리사업 중에 공익형에 가장 많이 참여하고 있었으며, 환경개선사업 활동을 가장 많이 하고 있었고, 생계비 마련을 위해 가장 많이 참여하였다. 둘째, 노인일자사업 중에는 소속기관 실무자와의 관계에 대한 만족도가 가장 높았고, 급여수준에 대한 만족도가 가장 낮았다. 셋째, 농촌노인들은 노인일자리사업 교육에 있어 가장 우선적으로 노인의 차이와 다양성을 고려한 맞춤형 교육 강화가 개선되어야 한다고 인식하였으며, 노인일자리사업에 참여하는 과정에서 교통문제로 인해 가장 많은 어려움을 느꼈다. 이런 결과를 볼 때, 농촌노인들의 특성과 욕구에 맞는 보다 다양한 형태의 프로그램 제공과 교통편의 제공을 통해 참된 자활이 이루어질 수 있도록 정책적 배려가 뒷받침되어야 할 것이다.

• 설비공학논문집
• /
• 제7권2호
• /
• pp.249-265
• /
• 1995

The performance of a refrigerant mixture of propane(R290)/isobutane(R600a) as a substitute for CFC12 was investigated in a domestic refrigerator with single evaporator. A thermodynamic cycle simulation indicated an increase in COP of a 1.7 to 2.4% with R-290/600a in the composition range of 0.2 to 0.6 mass fraction of R290 compared to CFC12. For the tests, two units($299{\ell}$, $465{\ell}$) were used. All refrigeration components remained the same throughout the tests, except that the length of capillary tube and amount of charge were changed for the mixture. The refrigerators were fully instrumented with more than 20 thermocouples, 2 pressure transducers, and watt/watt-hour meter for each refrigerator. 'Energy consumption test' and 'no load pulldown test' were performed under the same condition. The experimental results obtained with the same compressor indicated that R-290/600a mixture at 0.6 mass fraction of R290 showed a 3 to 5% increase in energy efficiency and a faster cooling speed compared to CFC12. The R-290/600a mixture showed a shorter compressor on-time and a lower compressor dome temperature than CFC12. In conclusion, the proposed hydrocarbon mixture seems to be an appropriate candidate to replace CFC12 without causing more environmental problems.

• 한국해양공학회지
• /
• 제17권5호
• /
• pp.82-87
• /
• 2003

A practical method to investigate the sharing architecture of FMS, for small and medium enterprises, on distributed heterogeneous environmental conditions is investigated. Because the industrial FMS model requires a reasonable size for actual work-site flexible operation, the initial facility expense is very heavy. The support for flexible cooperation of FMS, with some external different FMS, can reduce expenditures and provide greater functionality. While most FMS provide their operation process using an adequate mechanism, when used in isolation, such as island of automation, there is increasing demand for FMS that can cooperate. By exchanging intermediate products and information with other external FMS, products can be produced that cannot be produced alone, such as those that require various processes. This study first considers the sharing architecture of FMS for small and medium enterprises, and investigates the effects of the general sharing architecture of FMS on distributed heterogeneous environments, by using transducer approach to agentification. In this study, set-up station or in-out station takes charge of the gateway of intermediate products, and routes them among distributed heterogeneous FMS plants. The transducer approach is applied to web agent and set-up agent established interfaces, with system controller and setup controller. In this study, the FMS-established sharing architecture is able to obtain not only the internal flexibility, but also the external flexibility.

• 한국자동차공학회논문집
• /
• 제20권6호
• /
• pp.46-51
• /
• 2012

Fuel Cell Hybrid Vehicles (FCHVs) have become a major topic of interest in the automotive industry owing to recent energy supply and environmental problems. Several types of power management strategies have been developed to improve the fuel economy of FCHVs including optimal control strategy based on optimal control theory, rule-based strategy, and equivalent consumption minimization strategy (ECMS). The ECMS is applied in this study. This strategy is based on the heuristic concept that the usage of the electric energy can be exchanged to equivalent fuel consumption. This strategy is known as one of the promising solutions for real-time control of hybrid vehicles. The ECMS for an FCHV is introduced in this paper as well as the equivalent fuel consumption parameter. The relationship between the battery final state of charge (SOC) and the fuel consumption while changing the equivalent fuel consumption parameter is obtained for three different driving cycles. The function of the equivalent fuel consumption parameter is also discussed.

• 상하수도학회지
• /
• 제32권3호
• /
• pp.279-289
• /
• 2018

N-nitrosodimethylamine (NDMA) is a class of disinfection byproducts and a frequently detected nitrosamine with carcinogenic potentials. This review summarizes NDMA precursors, their formation mechanisms in chloraminated water, and mitigation strategies. Understanding the formation mechanism and characteristics of precursors is essential for developing a mitigation strategy. Dimethylamine (DMA), the most widely studied NDMA precursor, has an NDMA molar yield up to 3%. In comparison, a subset of tertiary amines, e.g., pharmaceuticals, generate up to 90% upon chloramination. Potent NDMA precursors, are characterized by their negative partial charge, low planarity values and molecular weight, and high bond length and $pK_a$ values. A nucleophilic substitution of tertiary amine on chloramine is a key reason for the high NDMA yield from the most potent NDMA precursors. The distribution and fate of NDMA in surface water, aquifers, and its formation in the distribution system can be mitigated through two strategies: (1) degrading or/removing NDMA after its formation and (2) pre-treatment of its precursor's prior chloramination.

• 설비공학논문집
• /
• 제22권12호
• /
• pp.837-844
• /
• 2010

In this study, performance of R1234yf and R1234yf/R134a mixture is measured on a heat pump bench tester in an attempt to substitute R134a used widely in mobile air conditioners (MACs). The bench tester is equipped with a open type compressor providing a nominal capacity of 3.5 kW. All tests are conducted under the summer cooling and winter heating conditions of 7/4 $5^{\circ}C$ and $-7/41^{\circ}C$ in the evaporator and condenser, respectively. For R1234yf/R134a mixture, measurements are made at 5%, 10%, and 15% of R134a by mass. Test results show that the coefficient of performance (COP) and capacity of R1234yf are up to 2.7% and 4.0% lower than those of R134a, respectively. For R1234yf/R134a mixture, the COP and capacity are up to 3.9% lower and 3.6% higher than those of R134a. For R1234yf and R1234yf/R134a mixture, the compressor discharge temperature is $4.1{\sim}6.7^{\circ}C$ lower than that of R134a while the amount of charge is reduced up to 11% as compared to R134a. 90%R1234yf/10%R134a is a better refrigerant than pure R1234yf in that it is less flammable and more compatible with existing R134a system. Based upon the results, it is concluded that R1234yf and R1234yf/R134a mixture are long term environmentally friendly solutions to mobile air-conditioners due to their excellent environmental properties with acceptable performance.

• Journal of Microbiology and Biotechnology
• /
• 제30권8호
• /
• pp.1261-1271
• /
• 2020

Cytochrome c_L (Cytc_L) is an essential protein in the process of methanol oxidation in methylotrophs. It receives an electron from the pyrroloquinoline quinone (PQQ) cofactor of methanol dehydrogenase (MDH) to produce formaldehyde. The direct electron transfer mechanism between Cytc_L and MDH remains unknown due to the lack of structural information. To help gain a better understanding of the mechanism, we determined the first crystal structure of heme c containing Cytc_L from the aquatic methylotrophic bacterium Methylophaga aminisulfidivorans MP^T at 2.13 Å resolution. The crystal structure of Ma-Cytc_L revealed its unique features compared to those of the terrestrial homologues. Apart from Fe in heme, three additional metal ion binding sites for Na⁺, Ca⁺, and Fe²⁺ were found, wherein the ions mostly formed coordination bonds with the amino acid residues on the loop (G93-Y111) that interacts with heme. Therefore, these ions seemed to enhance the stability of heme insertion by increasing the loop's steadiness. The basic N-terminal end, together with helix α4 and loop (G126 to Y136), contributed positive charge to the region. In contrast, the acidic C-terminal end provided a negatively charged surface, yielding several electrostatic contact points with partner proteins for electron transfer. These exceptional features of Ma-Cytc_L, along with the structural information of MDH, led us to hypothesize the need for an adapter protein bridging MDH to Cytc_L within appropriate proximity for electron transfer. With this knowledge in mind, the methanol oxidation complex reconstitution in vitro could be utilized to produce metabolic intermediates at the industry level.

• 지능정보연구
• /
• 제12권3호
• /
• pp.83-93
• /
• 2006

이 논문은 RFID를 이용한 무선 위치 인식 기술에 대한 것이다. 데이터의 RF 분석에 의한 수신된 신호의 강도로써 위치를 파악하고 위치 특성을 이해하는 실험을 하였다. 이 실험 시스템은 외부 환경 요인을 고려한 상태에서 5000대의 단말기를 이용하여 연구하였다. 이 위치 서비스는 특히 구매, 물류, 제조와 같은 일반산업, 자동조명/공조연동, 주차장 GATE 연동 서비스 등과 같은 많은 산업에서 이용될 것이다. 이 기술의 최적 솔루션은 일상생활의 지능형 정보가 필요하는 데이터의 저장과 접촉 비접촉에 토대를 둔 스마트 카드(전화카드, 은행카드..)등에도 이용될 것이다. 실내 위치 실험 방법은 서비스 및 추정된 위치 데이터를 이용한다. 이 연구의 결과는 아래와 같다. 첫째, Active RFID의 위치인식 시스템 설치 운영의 효율성과 둘째, 실내 무선위치 시스템의 추후 지능형 정보가 필요하는 여러 분야에서의 적용 가능성실험에 있다.

• 설비공학논문집
• /
• 제22권6호
• /
• pp.383-391
• /
• 2010

In this study, HFC152a, HFC134a/HFC152a and HC290/HFC134a/HFC152a mixtures are studied for the supplementary and alternative refrigerants for HFC134a used in automobile air-conditioners. Due to the high global warming potential of HFC134a, it has to be phased out in the long run. Thermodynamic performance of these refrigerants are measured in a bench tester of 3.5 kW capacity with an open type compressor under both summer and winter conditions. Test results show that the coefficient of performance (COP) and capacity of pure HFC152a and HFC134a/HFC152a mixture are 9.1~12% and 7% higher than those of HFC134a. As for the HC290/HFC134a/HFC152a, the COP is up to 9.5% higher than that of HFC134a with 1~2% of HC290 while that is up to 6.1% lower than that of HFC134a with 5% HC290. The capacity of the ternary mixture, however, is 8.6% higher than that of HFC134a at all compositions tested. The compressor discharge temperatures of all refrigerants tested are $6{\sim}10^{\circ}C$ higher than that of HFC134a. For all refrigerants, the amount of charge is reduced up to 32% due to the decrease in liquid density. Overall, these refrigerants provide good performance with reasonable energy savings with less environmental problem and thus can be used as long term alternatives for automobile air-conditioners.