• 한국정보통신학회논문지
• /
• 제8권1호
• /
• pp.158-169
• /
• 2004

독립전원으로 널리 사용되고 있는 납 축전지는 도서산간 벽지나 태양광을 이용하는 가로등 시스템과 같이 관리자가 없는 곳에서는 과 방전으로 납 축전지의 수명이 급격히 단축되어 고가의 시스템을 효율적으로 용하지 못하는 사례가 많이 발생한다. 이렇게 관리가 잘 되지 않는 곳에 설치된 납 축전지의 문제점인 과 방전을 방지하여 납 축전지의 수명단축을 예방하고자 마이크로프로세서를 사용한 효율적인 관리 시스템을 구축하였다. 제안된 관리시스템은 납 축전지의 충$.$방전 시 전류의 특성을 제어에 이용하였으며, 시스템 작동 중에는 납 축전지의 현재 잔량을 표시하여 관리자가 잔량을 표시할 수 있도록 하였다.

• 대한화학회지
• /
• 제46권1호
• /
• pp.26-36
• /
• 2002

$MoO_3$와 H-SAPO-34의 고체상 반응은 상자기성의 Mo(V) 화학종을 띤다. 탈수하면 Mo(V) 화학 종이 약하게 나타나지만 계속적으로 활성화 시키면 ESR로 규명할 수 있는 $Mo(V)_{5c}$와 $Mo(V)_{6c}$와 같은 Mo(V) 화학종이 생성된다. ESR과 ESEM 자료들은 $(MoO_2)^+$나 $(MoO)^{3+}$ 같은 옥소-몰리브덴 화학 종을 보여준다. $(MoO_2)^+$ 화학 종이 다음과 같이 더 합리적인 것 같이 보여진다. H-SAPO-34는 낮은 골격전하를 갖기 때문에 높은 양전하를 갖는 $(MoO)^{3+}$는 쉽게 안정화 되지 못한다. 소성된 H-SAPO-34와 도데카몰리브덴 규산 용액 사이의 용액 상태 반응은 단지 $MoO^{2+}$ 화학 종만을 발생한다. 마름모형 ESR 신호는 $D_2O$, $CD_3OH$, $CH_3CH_2OD$와 $ND_3$를 흡착할 때 관측되었다. Mo(V) 화학 종의 배위구조와 위치는 트리 펄스 전자 스핀반향 자료로 측정하였다. MoH-SAPO-34에 메탄올, 에틸렌 암모니아와 물이 흡착될 때 3분자, 1분자, 1분자와 1분자가 $(MoO_2)^+$에 각각 직접 배위하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권1호
• /
• pp.1-7
• /
• 2000

The SNOSFET memory devices with ultrathin ONO(tunnel oxide-nitride-blocking oxide) gate dielectric were fabricated using n-well CMOS process and investigated its characteristics. The thicknesses of tunnel oxide, nitride and blocking oxide were $23{\AA},\; 53{\AA}\; and\; 33{\AA}$, respectively. Auger analysis shows that the ONO layer is made up of $SiO_2(upper layer of blocking oxide)/O-rich\; SiO_x\N\_y$. It clearly shows that the converting layer with $SiO_x\N\_y(lower layer of blocking oxide)/N-rich SiO_x\N\_y(nitride)/O-rich SiO_x\N\_y(tunnel oxide)$. It clearly shows that the converting layer with $SiO_x\N\_y$ phase exists near the interface between the blocking oxide and nitride. The programming condition of +8 V, 20 ms, -8 V, 50 ms is determined and data retention over 10 years is obtained. Under the condition of 8 V programming, it was confirmed that the modified Fowler-Nordheim tunneling id dominant charge transport mechanism. The programmed threshold voltage is distributed less than 0.1 V so that the reading error of memory stated can be minimized. An $8\times8$ NAND type flash EEPROM with SONOSFET memory cell was designed and simulated with the extracted SPICE parameters. The sufficient read cell current was obtained and the upper limit of $V_{TH}$ for write state was over 2V.

• 전기화학회지
• /
• 제7권3호
• /
• pp.131-137
• /
• 2004

Sol-gel method which provides better electrochemical and physiochemical properties compared to the solid-state method was used to synthesize the material of $LiFe_yMn_{2-y}O_4$. Fe was substituted to increase the structural stability so that the effects of the substitution amount and sintering temperature were analyzed. XRD was used for the structural analysis of produced material, which in turn, showed the same cubic spinel structure as $LiMn_2O_4$ despite the substitution of $Fe^{3+}$. During the synthesis of $LiFe_yMn_{2-y}O_4$, as the sintering temperature and the doping amount of Fe(y=0.05, 0.1, 0.2)were increased, grain growth proceeded which in turn, showed a high crystalline and a large grain size, certain morphology with narrow specific surface area and large pore volume distribution was observed. In order to examine the ability for the practical use of the battery, charge-discharge tests were undertaken. When the substitution amount of $Fe^{3+}\;into\;LiMn_2O_4$ increased, the initial discharge capacity showed a tendency to decrease within the region of $3.0\~4.2V$ but when charge-discharge processes were repeated, other capacity maintenance properties turned out to be outstanding. In addition, when the sintering temperature was $800\~850^{\circ}C$, the initial capacity was small but showed very stable cycle performance. According to EVS(electrochemical voltage spectroscopy) test, $LiFe_yMn_{2-y}O_4(y=0,\;0.05,\;0.1,\;0.2)$ showed two plateau region and the typical peaks of manganese spinel structure when the substitution amount of $Fe^{3+}$ increased, the peak value at about 4.15V during the charge-discharge process showed a tendency to decrease. From the previous results, the local distortion due to the biphase within the region near 4.15V during the lithium extraction gave a phase transition to a more suitable single phase. When the transition was derived, the discharge capacity decreased. However the cycle performance showed an outstanding result.

• 한국관광식음료학회지:관광식음료경영연구
• /
• 제8권
• /
• pp.21-33
• /
• 1997

This study reviews the scientific management theories and discusses those theories within the food service industry. By providing the principles and the practical implications of the theories on the food service industry, this study tries to identify their philosophies and usefulness to the industry so that the managers in the industry use them in their dylmanic operations. In the fastly changing modern globalized world, we now face a situation where it's becoming more and more difficult to mange a restaurant business. In order to build a food industry business that can maintain a continuous development in today's business environment, one will have to apply the professional management theory in a cost-reduce strategy. It is more important though to have managers, organization members, in short, any person who can work to be motivated in accomplishing these two major issues-income increase and cost reduction. In this erawhere it's getting so difficult for researches on possible strategies for these business managers to overcome their difficulties. It is for certain that in the upcoming second millenium the travel and tourism industry will be one of the world's biggest industry worldwide. Korea's hotel industry has developed since the 1988 Seoul Olympic Games and has shown great amount of competition within the same business. Thus managers have become acquainted with the "know-how" strategy and the practical and scientific managemnet theories were introduced. This helped not only to increase income but also to maximize profit. However, rather than concentration on the "Hard-ware" aspect "Soft-ware" related professional management strategies were developed along with professionalism and human service were emphazied. As such, the actual cost of food and beverages are for the hotel industry business managers the biggest shortterm expense item. Due to the natural state of food items, there is a great chance of "Loss" in preservance, and this is the reason it is complicated to effectively maintain food. As a consequence, very often, the failure to managea hotel or restaurant depends on the capability of the food and beverage preservance mangement: on how they are able to manage effectively the original price of food and beverage. Finally, the main problem of the original price management of food and beverage in Korean hotels are: a) No fixation of set price b) The difficulty to calculate the price difference between a set price and an original price. c) Lack of professinalism in managing the food and beverage original price. d) Lack of perception of the highest ranking management personnels. So as to reform these matters it is necessary to : a) Reform on the management accounting system b) Emphasize to the people in charge on the idea of original price management c) Reinforce original price mangement prevention and assurance of indepedent inspection rights d) Reat manpower

• 한국재료학회지
• /
• 제9권6호
• /
• pp.635-653
• /
• 1999

The present work considers work considers research strategies to address global warming. Specifically, this work considers the development of technologies of importance for the reduction of greenhouse gas emission and, especially, the materials that are critical to these technologies. It is argued that novel materials that are essential for the production of environmentally friendly energy may be developed through a special kind of engineering: interface engineering, rather than through classical bulk chemistry. Progress on the interface engineering requires to increase the present state of understanding on the local properties of materials interfaces and interfaces processes. This, consequently, requires coordinated international efforts in order to establish a strong background in the science of materials interfaces. This paper considers the impact of interfaces, such as surfaces and grain boundaries, on the functional properties of materials. This work provides evidence that interfaces exhibit outstanding properties that are not displayed by the bulk phase. It is shown that the local interface chemistry and structure and entirely different than those of the bulk phase. In consequence the transport of both charge and matter along and across interfaces, that is so important for energy conversion, is different than that in the bulk. Despite that the thickness of interfaces is of an order to a nanometer, their impact on materials properties is substantial and, in many cases, controlling. This leads to the conclusion that the development of novel materials with desired properties for specific industrial applications will be possible through controlled interface chemistry. Specifically, this will concern materials of importance for energy conversion and environmental monitoring. Therefore, there is a need to increase the present state of understanding of the local properties of materials interfaces and the relationship between interfaces and the functional properties of materials. In order to accomplish this task coordinated international efforts of specialized research centres are required. These efforts are specifically urgent regarding the development of materials of importance for the reduction of greenhouse gases. Success of research in this area depends critically on financial support that can be provided for projects on materials of importance for a sustainable environment, and these must be considered priorities for all of the global economies. The authors of the present work represent an international research group economies. The authors of the present work represent an international research group that has entered into a collaboration on the development of the materials that are critical for the reduction of greenhouse gas emissions.

• Journal of Electrical Engineering and Technology
• /
• 제9권3호
• /
• pp.803-811
• /
• 2014

The moment when Electrical Vehicle (EV) starts charging or discharging is one of the most important parameters in estimating the impact of EV load on the grid. In this paper, a decision-making problem of determining the start time of charging and discharging during allowed period is proposed and studied under the uncertainty of real-time price. Prospect theory is utilized in the decision-making problem of this paper for it describes a kind of decision making behaviors under uncertainty. The case study uses the parameters of Springo SGM7001EV and adopts the historical realtime locational marginal pricing (LMP) data of PJM market for scenario reduction. Prospect values are calculated for every possible start time in the allowed charging or discharging period. By comparing the calculated prospect values, the optimal decisions are obtained accordingly and the results are compared with those based on Expected Utility Theory. Results show that with different initial State-of-Charge ($SoC_0$) and different reference points, the optimal start time of charging can be the one between 12 a.m. to 3 a.m. and optimal discharging starts at 2 p.m. or 3p.m. Moreover, the decision results of Prospect Theory may differ from that of the Expected Utility Theory with the reference points changing.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.307-308
• /
• 2007

This work shows the experimental results obtained from ageing at a temperature of 100 C for 48, 70 and 312 h, although the application of AC electrical tension in samples and the measuring of current leakage are presented. The measurements in samples were carried out with samples prepared from the deformulated commercial materials and respectively reformulated into thin films. The obtained results showed the mechanisms of conduction of samples in low and high electric fields. It was also identified an electric tension transition showing that in low fields it prevails the Ohm's law conduction, and in high electric fields it prevails the conduction of space charge limited current (SCLC). These results can support the natural rubber formulation process having as their main objective the reducing of the mechanisms that occur under high conduction current in high electric fields, which leads the material to a dielectric breakdown. Raw Natural rubber in Brazil is extracted from rubber trees (Hevea brasiliensis) in farms in So Paulo State by using some new plantation technology in smaller spaces, with trees placed a few meters from each other. In the Amazon rain forest the rubber trees are found naturally and their spacing may be of hundreds of meters or even kilometers between them. It is necessary to research this raw material from different internationally standard clones to characterize dielectric and electric properties for industrial applications. Moreover, this natural material has a low commercial price when compared to the synthetic ones.

• 해양환경안전학회지
• /
• 제29권2호
• /
• pp.223-229
• /
• 2023

해수이차전지는 해수를 양극으로 사용하는 차세대 이차전지이다, 해양 자원을 사용하여 가격 경쟁력과 높은 친환경성, 그리고 해양 애플리케이션에 적합한 구조를 가진다. 이러한 장점을 기반으로 지속적 연구개발을 통해 자연 해수 노출을 가정한 파우치 타입 및 각형 타입이 개발되어 왔다. 그러나 이차전지는 전기적 특성상 사용 환경에 따라 용량 및 내부 임피던스가 달라진다. 이러한 특성은 전지의 수명 예측에 활용될 뿐만 아니라 활용하고자 하는 상황에 맞는 용량과 출력에 직접적인 영향을 미친다. 따라서 본 논문에서는 해수이차전지의 사용 환경에 따른 용량 측정과 SoC-OCV 측정 방법을 통한 내부 저항을 분석하고자 한다.

• 대한화학회지
• /
• 제34권3호
• /
• pp.239-247
• /
• 1990

기체상 $S_N2$ 반응의 형태는 중성 2분자반응, 용매화반응, 이온반응 등으로 나눌 수 있으며, 메카니즘적으로 중성 2분자 반응은 retention 생성물을 만들며 이온반응은 inversion 생성물을 만든다. 한편 용매인 물 한 분자에 의하여 6- 중심 건이상태를 거치는 용매화반응의 경우는 친핵체(또는 이탈기)및 치환기에 의한 전자효과와 입체효과에 따라 두 생성물이 경쟁적으로 만들어진다. 여기에서 얻어진 결과를 이용하여 이온반응의 경우, 중앙 methly group을 매우 bulky 하게 하고 이탈기 능력을 크게 해줌과 동시에 음이온인 친핵체의 하전을 분산시켰을 때 inversion과 retention TS 사이의 에너지 차이가 아주 작게 나타났다. $S_N2$ 반응의 반응중심을 보다 더 큰 2주기 원소로 바꾸었을 때, 5가의 전이상태에 미치는 입체장애가 작아지므로 활성화에너지 장벽이 낮아진다. 반면, 같은 주기에서 원자의 크기가 작아지면 에너지 장벽은 올라간다. B원자의 경우 에너지 장벽이 가장 낮은데, 그것은 C와 N 원자보다도 더 크며 또한 4가의 전이상태를 이루므로 입체장애가 거의 무시되기 때문이다.