골프 에티켓

오지철 제주대학교 통역대학원 2015 국내석사

분산전원 단독운전 시 과전압 분석 및 대책

차재훈 충북대학교 2018 국내석사

Nowadays, distributed generations is being to the fore as an alternative of future power supply and the number of DGs connected to the conventional power system is steadily increasing. Especially, the use of Energy Storage System(ESS) is high in potential value because it can be applied to Electric Vehicle(EV), Uninterrupted Power Supply (UPS), and the new way of electricity business. However, these generators which are designed using power electronics can give rise to various power quality problems such as overvoltage or overcurrent Above all, unintentional islanding operation can happen to conventional power system when power grid is separated from the DGs during an operation. To avoid this operation, many standards on prevention of unintentional islanding are established in various countries. However, these standards have different sections like acceptable time because the properties of power systems also differ from each other. It means that negative effect caused by unintentional islanding may happen in case of particular standards despite thorough compliance. Hence, it is necessary to modify the standard in strict way and consider an additional condition about prevention of unintentional islanding. In unintentional islanding operation, The overvoltage might happen depending on the power generation and power consumption. Currently, there are many precautions on this problem : fast stop of DG by anti-islanding detection, avoidance of light load condition and software solutions. However, it is nearly impossible for system operators to adjust the ratio of power generation and power consumption in power system at all time. In some cases, these overvoltage phenomenon might not happen even though unintentional islanding occurs. It implies that unnecessary stop of DGs is also avoidable. The critical problem of papers published so far is that there is a difficulty in application of their methods proposed because it is impossible practically to figure out all the location of many a load and to measure the active and reactive power of load just before islanding condition. Therefore, at this point we proposed a method to solve the problem.

리튬이온전지의 외부온도에 따른 과방전 특성분석

문명지 충북대학교 2024 국내석사

Lithium-ion battery is widely used in industry and daily life, and stability is key. Waste battery recycling is an important issue, requiring safe discharge before the battery shredding and wet recovery process. This paper studies the effect of external temperature on overdischarge characteristics and explores the possibility of use in the lithium-ion battery recycling process. The study covers temperature conditions and overdischarge characteristic analysis methods, and provides information on the operating principles of lithium-ion batteries, charge/discharge characteristics, overdischarge concepts, and safety issues. In this paper, the overdischarge characteristic analysis method is proposed according to external temperature and compared with existing research results. In experiments and discussions, the experimental method, conditions, measurement equipment, and data processing methods are explained, and overdischarge characteristics according to external temperature are analyzed. This research is expected to contribute to the development of lithium-ion battery recycling processes.

제어코일 전류를 활용한 가스밀폐형 직류 접촉기 동작상태 측정 기법

차승우 충북대학교 2024 국내석사

As electric vehicles and LVDC distribution systems expand, demands for DC contactor are increasing. DC Contactor is a device that acts as a switch (On/Off) in the system, and the most important performance is stability of operation. To check if the operation is normal or not, the pickup voltage applied to the control coil is measured and judged. However, it is difficult to confirm the complete operating state of the DC contactor using the pickup voltage measurement method. In order to solve this problem, this paper presents a method to determine whether or not a DC contactor is complete operating through changes in electromotive force applied to the control coil. A theoretical basis is presented to explain the change in electromotive force, and it is verified that the method is able to accurately determine the on-off state through experiments.

다수 분기회선을 갖는 비접지 배전계통의 SLGF 검출을 위한 SGR 정정

구대현 충북대학교 2024 국내석사

Ungrounded system is mainly applied to the distribution system within the premises of high-voltage customers. The reason is that in the event of single-line ground fault(SLGF), the ground fault current is too small and continuous electricity supply is possible, and the inductive interference on communication lines is smaller than other grounding methods. As the protection method for SLFG in ungrounded system, selective grounding relay(SGR) is commonly applied, which is composed of GPT detecting zero-sequnece voltage and ZCT detecting fault current. However, since those zero-sequnece voltage and fault current vary depending on the ground capacitance and fault resistance value in the distribution system, it is difficult in practice to set the values. In this paper, a method is proposed that determine the set values of GPT and ZCT required for SGR operation by considering various ground capacitance and fault resistance values. To verify this method, the target ungrounded system is designed using PSCAD/EMTDC and it was verified that SLGF detection can be successful.

임피던스정합용 경사형 도파관을 이용한 저압 마이크로웨이브 플라즈마 발생장치의 설계

안재윤 충북대학교 2018 국내박사

Recently, the industry is developing more rapidly than ever, but energy efficiency and environmental issues are also being raised. Among them, CF4, which is a non-degradable gas, is generated in the semiconductor industry, and many researches have been conducted on the plasma generator as a method for efficiently resolving the CF4. To date the application of a high efficiency microwave plasma generator with high energy density and reproducibility under low-pressure condition has been proposed for the efficient decomposition. However, due to the impedance mismatch in the waveguide and reactor, energy transfer efficiency is reduced and microwave is unbalanced, and as a result, CF4 could not be decomposed effectively. In this paper, a circular reactor design method using tapered waveguide and slot to solve the problem of microwave plasma generator as described above is proposed. As a design method, the staircase structure is used for the impedance matching of the waveguide, which is the passage of the microwave, so that the microwave energy can be transmitted well. Since this step structure has the advantage of minimizing the reflection within the waveguide. Also, a method to position capacitive window at the end of the waveguide for energy accumulation around the slot proposed. Finally, considering the staircase structure and capacitive window, a design method to determine the waveguide length, slot size, and dielectric thickness is suggested. To verify the design method, the simulation analysis using HFSS s/w package and the testing through fabrication of demonstrated facilities are conducted. First, we modeled the reactor using the proposed tapered waveguide and slot design method, and confirmed its validity by simulating S-parameter which means microwave field distribution concentration and to input-to-output voltage ratio at each frequency. Meanwhile, the microwave plasma generator was built based on the design value calculated by simulation. DRE(destruction and removal efficiency) of CF4 was analyzed through FT-IR(fourier transform infrared) according to changing the applied voltage, gas flow rate, pressure and dielectric length. As a result of the analysis, the concentration ratio of the CF4 gas before and after the treatment was higher than 90% by the strong energy of the microwave plasma considering the impedance matching. Therefore, it was confirmed that more than 90% of CF4 gas, which is a decomposing gas, can be efficiently decomposed and treated by the tapered waveguide and slotted circular reactor design method proposed in this paper. In future, its successful application and role is expected in solving the CF4 environmental problem of the semiconductor industry field.

내부 결함에 따른 변압기 절연유의 부분 방전 특성 연구

김성태 충북대학교 2024 국내석사

Power transformers play a vital role in ensuring stable power supply and cost-effective energy transmission. Among the key components, insulating oil serves the purposes of electrical insulation, heat dissipation, and cooling within transformers. Currently used mineral oils may pose environmental concerns. Hence, research into environmentally friendly alternatives such as vegetable-based and synthetic insulating oils is underway and has been implemented in some countries. This study evaluates the impact of environmentally friendly insulating oils on power transformers. To achieve this, partial discharge (PD) characteristics were assessed by combining Duval triangle analysis and PRPD (Phase Resolved Partial Discharge) analysis in a simulated environment representing internal faults in power transformers. Each simulated fault cell representing floating electrode faults and surface discharge faults, essential types of internal faults, were created using four types of insulating oils: Mineral Oil, FR3, MIDEL 7131, and BIOTRAN 35. This facilitated a comparative analysis of insulation characteristics and fault types. The PRPD analysis involved obtaining PRPD patterns for each insulating oil using a PD detector and conducting data pattern analysis using a Python program. Floating electrode faults exhibited irregular traits and wide distributions, whereas surface discharge faults showed active partial discharge occurrences, particularly around the centroid. Additionally, the Dissolved Gas Analysis (DGA) evaluated total discharge quantities and seven gas components in each fault cell. The non-linear relationship between total discharge quantities and gas volumes highlighted differences in gas production based on the chemical properties of the insulating oil. Furthermore, visualization of gas concentrations using the Duval triangle technique aided in understanding the evolving state of the insulating oil. These complementary analytical methods showcased the utility of introducing environmentally friendly insulating oils, providing insights into their impact on maintenance and operation of power transformers. Such analytical methodologies are anticipated to significantly enhance maintenance and operation in the realm of implementing environmentally friendly insulating oils in power transformers. * A thesis for the degree of Master in February 2024.

종합병원에서의 비상시 전원자동절체방식에 대한연구

김상길 충북대학교 2024 국내석사

Long-term power outages in places such as surgery centers, emergency centers, and intensive treatment centers in hospitals are directly linked to casualties. Therefore, the hospital's power system requires reliability and safety. Nevertheless, most hospitals in Korea are causing long-term power outages due to the failure of the ATS (Automatic Transfer Switch), and there is no data that suggests a solution to this problem. Therefore, in this study, the power receiving equipment, operation status, and accident cases of general hospitals A and B were investigated for the purpose of improving power outage time and suggesting stable operation and management methods for ACB and ATS, targeting 400-bed general hospitals. A system of emergency power transfer mechanism was established to use the By Pass line to improve power outage time and ACB to replace ATS, and its adequacy was proven through power outage time analysis in an empirical test.

정제 코팅기의 분사펌프 유량제어시스템 설계

고정인 충북대학교 2024 국내석사

With the development of pharmaceutical technology, many new medicines are being developed and marketed by spraying the main ingredient in the coating process to extend the duration of effect and reduce medicine intake, increasing the importance of the coating process in the tablet manufacturing process. In order to improve the coating quality of tablets, the spray pump control method was changed from a simple speed control method to a speed control method using a flow meter to spray at a constant flow rate without changing the flow rate due to deformation of the peristaltic pump tube due to long-term spray, and the spray pump flow rate was changed to a speed control method using a flow meter. This thesis presents a design method for a tablet coating spray pump flow control system. Through this study, design, and experiment, it is hoped that when using a Coriolis flow meter used for precise flow control, it will help to check the viscosity of the solution used and optimize the viscosity and spray time. It is hoped that this thesis's design, manufacture, and demonstration tests of the tablet coating process will improve the quality of the tablet coating, reduce the setting time and working time of the coating solution spray parameter, and help human health. * A thesis for the degree of Master in February 2024.

분산전원이 도입된 배전계통의 전압 조정을 위한 개선된 LDC 제어 방법

김종빈 충북대학교 2024 국내석사

In an effort to reduce the use of fossil fuels and carbon emissions, Korea is announcing a policy to increase the amount of renewable energy generation. Distributed Generation (DG) is environmentally friendly, but the introduction of distributed generation in the distribution system changes the existing unidirectional power flow to bidirectional, resulting in reverse currents, causing voltage fluctuations, lower power quality, and problems with protection cooperation. This reverse current also causes problems with voltage regulation in the distribution system. Conventional Line Drop Compensation (LDC) control is able to control when a small capacity distributed generation is introduced, but problems arise in voltage regulation when a distributed generation with a larger output is introduced. Therefore, in this paper, we analyze the current LDC control, present a new algorithm for voltage regulation according to light and peak loads in distribution lines, and analyze it using PSCAD/EMTDC software.