• Journal of Electrochemical Science and Technology
• /
• 제12권1호
• /
• pp.1-20
• /
• 2021

In-depth knowledge of electrode processes is crucial for determining the electrochemical performance of lithium-ion batteries (LIBs). In particular, the conduction mechanisms of charged species in the electrodes, such as lithium ions (Li+) and electrons, are directly correlated with the performance of the battery because the overall reaction is dependent on the charge transport behavior in the electrodes. Therefore, it is necessary to understand the different electrochemical processes occurring in electrodes in order to elucidate the charge conduction phenomenon. Thus, it is essential to conduct fundamental studies on electrochemical processes to resolve the technical challenges and issues arising during the ionic and electronic conduction. Furthermore, it is also necessary to understand the transport of charged species as well as the predominant factors affecting their transport in electrodes. Based on such in-depth studies, potential approaches can be introduced to enhance the mobility of charged entities, thereby achieving superior battery performances. A clear understanding of the conduction mechanism inside electrodes can help overcome challenges associated with the rapid movement of charged species and provide a practical guideline for the development of advanced materials suitable for high-performance LIBs.

• 한국군사과학기술학회지
• /
• 제25권3호
• /
• pp.275-284
• /
• 2022

Linear Shaped Charge(LSC) is widely used as a separation system in the field of weapon system. However, there are some disadvantages that are charging lots of explosives due to lack of uniformity and having difficulties of the design of liner and explosives because of manufacturing process. In order to solve these problems, Precision Linear Shaped Charge(PLSC) that can design a liner independently and charge explosives uniformly has been developed. In this study, PLSC was designed to have a proper liner shape and amount of explosives, and the penetration test of PLSC with different stand-off distance from liner to target was conducted. On the basis of the penetration test results of PLSC, the numerical analysis method using AUTODYN was established and verified. The penetrative mechanism and characteristics of PLSC with targets of different materials was analyzed from experimental and numerical results.

• 융복합기술연구소 논문집
• /
• 제11권1호
• /
• pp.19-23
• /
• 2021

These days, sales of battery electric vehicles have been rapidly increasing due to the strict CO₂ regulations. However, since it take too long to measure the energy economy of electric vehicles, it has been required to improve the procedure of energy economy measurement. In order to improve this problem, the present study analyzed the battery charge/discharge pattern according to the changes in battery SOC (state of charge). In general, the energy economy test is started with a battery SOC charged to 100 %. However, it was identified that when the battery is fully charged, it can actually be charged over the 100 % (e.g., 100.5 %). This can induce errors in the energy economy measurement. Therefore, the present study recommend to start the test at SOC 99.9 %. The regenerative braking was partly restricted for the SOC over 90 %. This made it difficult to estimate the overall energy economy of the electric vehicle. However, it was identified that there was no change in the battery charge/discharge characteristics under the SOC 90 %. Therefore, the energy economy test can be shortened by predicting the overall energy economy through a short mileage test.

• 대한토목학회논문집
• /
• 제31권1D호
• /
• pp.51-63
• /
• 2011

현재 유료도로인 창원터널은 출 퇴근 시간대에 지 정체 현상이 상습적으로 일어나 교통혼잡비용을 가중시키고, 이용차량들의 불만이 날로 증대되고 있는 실정이며, 무료화에 위한 많은 민원들이 요구되어 왔으나, 유료도로인 창원터널의 조기 무료화 도입이 민원의 해소는 가능하나 제2창원터널의 개통없이는 용량 초과에 따른 지체가 더욱더 가중될 것으로 보여 근본적인 해결방안이 될 수 없음이 기정사실화 되고 있다. 따라서 본 논문에서는 용량 초과된 터널구간의 지정체가 더욱 더 심화되지 않도록 교통시설 개선과 교통수요 관리 등으로 개선 방안을 제시하는 것이 바람직하며, 유료도로의 조기 무료화는 대안별 시뮬레이션 분석 및 교통혼잡비용 추정 결과에 따른 객관적인 분석을 통해 이루어져야 하며, 건설소요 상환금을 조기 해결하고 유지 관리를 위한 최소한의 경비 확보가 우선시되어야 하므로 통행료에 따른 수익자 부담의 원칙을 준수하는 것이 불특정다수의 피해를 최소화할 수 있어 유료도로의 조기 무료화에 따른 실익을 신중하게 추진하는 것에 그 목적이 있다.

• 대한공업교육학회지
• /
• 제30권2호
• /
• pp.23-32
• /
• 2005

The purpose of this study is to investigate and analyze the actual state of teaching and learning methods which are applied to the vocation inquiry section-related subjects of the College Scholastic Ability Test(CSAT) by the teachers who teach specialized subjects of vocational high schools. In order for us to get the background and feature of establishment in the area of vocation inquiry section of the CSAT, previous studies and literature was analyzed and sample survey on the 600 teachers who teach the vocation inquiry section-related subjects was made. The result of this survey is as shown below; First, the teachers who are in charge of vocation inquiry section-related subjects understand that theory and practice is in the ratio 60.76:39.24 and ratio of theory is higher than that of practice. Second, teaching and learning method which is the most relevant to the vocation inquiry section is in the order of lecture(83.9%), experiment & practice(50.4%), computerized learning(41.1%). Third, teaching and learning method which is the most used by the teachers who are in charge of vocation inquiry section-related subjects is in the order of lecture(85.8%), computerized learning(50.1%), experiment and practice(44.4%). Forth, the most desirable teaching and learning method which the teachers who are in charge of vocation inquiry section for this subject believe is in the order of lecture(62.7%) experience & practice(47.7%), computerized learning(44.4%). In light of this result, even though there were not so much difference among the teaching-learning methods which are the most consistent with the contents of the subject in relation to the vocation inquiry section, the most used teaching-learning method by the teachers who teach vocation inquiry section-related subjects and the most desirable teaching-learning method which the teachers who are in charge of vocation inquiry section believe, the most used teaching-learning method by the teachers who are in charge of the vocation inquiry section is lecture. Therefore, it is necessary for us to reinforce the contents in relation to the practice & experiment so that the experience and application can be accumulated and improved through practice which is the specialty of the course of the study in the vocational high school and various teaching and learning method should be developed in consideration of contents of the subject, capability & quality of the learners and status of a classroom.

• 한국자동차공학회논문집
• /
• 제13권4호
• /
• pp.182-189
• /
• 2005

In order to investigate the effect of premixed gasoline, diesel fuel, and n-heptane charges on the combustion and exhaust emission characteristics in a direct injection (DI) diesel engine, the experimental studies are performed. The premixed fuels are injected into the premixing chamber that installed upstream of the intake port in order to minimize the inhomogeneity effect of premixed charge. The injection nozzle for directly injected fuel is equipped in the center of the combustion chamber. The air temperature control system is equipped in the intake manifold to examine the effect of air temperature. The experimental results of this study show premixing fuel is effective method to reduce the NOx and soot emissions of diesel engine. NOx emissions are linearly decreased with increasing premixed ratio for the three kinds of premixed fuels. The heating of intake air $(80^{\circ}C)$ reduced the deterioration of BSFC in high premixed ratio, because it promotes evaporation of premixed diesel droplet in the premixing chamber.

• Nuclear Engineering and Technology
• /
• 제41권5호
• /
• pp.723-728
• /
• 2009

The response property of the CZT detector ($5{\times}5{\times}5\;mm^3$), widely used in photon spectroscopy, was evaluated by considering the charge collection efficiency, which depends on the interaction position of incident radiation, A quantitative analysis of the energy spectra obtained from the CZT detector was also performed to investigate the tail effect at the low energy side of the full energy peak. The collection efficiency of electrons and holes to the two electrodes (i.e., cathode and anode) was calculated from the Hecht equation, and radiation transport analysis was performed by two Monte Carlo codes, Geant4 and MCNPX. The radiation source was assumed to be 59.5 keV gamma rays emitted from a $^{241}Am$ source into the cathode surface of this detector, and the detector was assumed to be biased to 500 V between the two electrodes. Through the comparison of the results between the Geant4 calculation considering the charge collection efficiency and the ideal case from MCNPX, an pronounced difference of 4 keV was found in the full energy peak position. The tail effect at the low energy side of the full energy peak was confirmed to be caused by the collection efficiency of electrons and holes. In more detail, it was shown that the tail height caused by the charge collection efficiency went up to 1000 times the pulse height in the same energy bin at the calculation without considering the charge collection efficiency. It is, therefore, apparent that research considering the charge collection efficiency is necessary in order to properly analyze the characteristics of CZT detectors.

• 한국정보통신학회논문지
• /
• 제19권4호
• /
• pp.933-939
• /
• 2015

일반전원이 공급되지 않은 광파표지는 태양광을 이용한 전력공급시스템을 사용하고 있다. 이러한 전력공급시스템에서는 충 방전조절기의 역할이 매우 중요하다. 항로표지의 효과적인 관리를 위해 도입된 IT기술(AIS통신 등)은 광파표지에 전력을 사용하는 장치를 추가하게 됨으로써 충 방전조절기의 중요성이 증가하고 있다. 현재 운용되는 충 방전조절기는 항로표지 내부에 부착되어 해상환경에 따라 점검 및 확인하는데 어려움이 있다. 이를 해결하기 위해서 본 논문에서는 충 방전조절기에 블루투스 모듈을 구성하여 근거리 점검이 가능한 모니터링 시스템을 제안하였다. 제안한 시스템은 도입 비용이 적고, 구성이 간편하여 다양한 항로표지에 응용가능한 장점이 있다. 또한 근거리에서 충 방전조절기의 실시간 상태정보를 확인할 수 있어서 점검 비용을 절감하고, 점검 시 발생 가능한 위험요소를 줄일 수 있다.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 2000년도 제26회 펄프종이기술 국제세미나
• /
• pp.1-10
• /
• 2000

The development of paper machines, increasing machine speeds with new, mostly low basis weight and/or high ash content paper grades, as well as the fact that several trends regarding process items have increased the sensitivity of papermaking. At the same time, papermakers are looking for flexibility in the production line. We can say that with all PMs the biggest benefits with the lowest capital spending can be achieved by focusing on improved wet end management. In order to manage wet end chemistry on a paper machine, our goal is to control sub-process through which we can influence the operation of the entire wet end with maximum effect. Key measurements and controls are-white water consistency control which is the most effective way to control retention - charge demand measurement and control which takes care of concentration of the anionic material entering to PM -ash measurements and controls which are deeply related to retention and paper quality This paper presents and concentrates to two of these key controls ; retention and charge. The purpose of charge control is to give the process control the tools to react to changes caused by amount of dissolved and colloida material incoming to wet end system. It is called coagulation or fixing control. Retention control is then taking care of retention aid flow to the process by responding any changes seen in white water consistency. It is called flocculation control. Each of these solutions separately , and even more effectively all together, stabilize the wet end operations and so greatly improve the produced paper quality and machine runnability. Practical results will be presented and they are referring to the latest mill cases. We have developed the first wet end measuring system in the late 1980s and control solutions based on this modern measuring technology were completely updated in 1990s. This paper introduces the principle, operation , and results of our unique wet end analyzers (retention and charge ) which are at the level of automation solutions as a part of paper machine quality control Especially our newest member of the platform , on-line charge analyzer has reached and set new standards to the on-line charge monitoring.

• 펄프종이기술
• /
• 제32권5호
• /
• pp.44-53
• /
• 2000

The development of paper machines, increasing machine speeds with new, mostly low basis weight and/or high ash content paper grades, as well as the fact that several trends regarding process items have increased the sensitivity of papermaking. At the same time, papermakers are looking for flexibility in the production line. We can say that with all PMs, the biggest benefits with the lowest capital spending can be achieved by focusing on improved wet end management. In order to manage wet end chemistry on a paper machine, our goal is to control subprocesses through which we can influence the operation of the entire wet end with maximum effect. Key measurements and controls are - white water consistency control which is the most effective way to control retention. - charge demand measurement and control which takes care of concentration of the anionic material entering to PM. - ash measurements and controls which are deeply related to retention and paper quality. This paper presents and concentrates to two of these key controls: retention and charge. The purpose of charge control is to give the process control the tools to react to changes caused by amount of dissolved and colloidal material incoming to wet end system. It is called coagulation or fixing control. Retention control is then taking care of retention aid flow to the process by responding any changes seen in white water consistency. It is called flocculation control. Each of these solutions separately, and even more effectively all together, stabilize the wet end operations and so greatly improve the produced paper quality and machine runnability. Practical results will be presented and they are referring to the latest mill cases. We have developed the first wet end measuring system in the late 1980s and control solutions based on this modern measuring technology were completely updated in 1990s. This paper introduces the principle, operation, and results of our unique wet end analyzers (retention and charge) which are at the level of automation solutions as a part of paper machine quality control. Especially our newest member of the platform, on-line charge analyzer has reached and set new standards to the on-line charge monitoring.