Modeling and Simulation about Long Term Dynamics Using Real Time Digital Simulator

Nam, Su-Chul,Song, Ji-Young,Lee, Jae-Gul,Shin, Jeong-Hoon,Kim, Tae-Kyun The Korean Institute of Electrical Engineers 2012 The Journal of International Council on Electrical Vol.2 No.4

RTDS (Real Time Digital Simulator) has several benefits. First, current power system simulation tool dose not simulate electromagnetic transient phenomenon, but it is possible using RTDS. Second, off-line electromagnetic transient simulation tools (EMTDC, PS-CAD, etc.) do not simulate real-time analysis, but RTDS is able to do real-time analysis. Third, RTDS is able to simulate related external devices those are protection relays, new developed control devices and power system devices. So many engineers use RTDS in power industry using these advantages of RTDS. KEPCO (Korea Electric Power Corporation) also use RTDS for developing new special protection scheme that is a new developed protection scheme for maintaining voltage stability in metropolitan area using real time synchro phasor data. Voltage stability phenomena of power system are divided three parts by time period. Those are transient, short term and long term voltage stability phenomena. Almost critical voltage stability problems happen in long term time period. Because power system devices and loads those influence voltage stability have long term dynamic characteristic. So if we want correct results of voltage stability analysis, then we have to analyze long term dynamic about voltage stability. Long term dynamic characteristic of voltage stability that is influenced by under voltage tap changer, over excite limiter, dynamic loads and so on. Unfortunately, we had not an analysis environment about long term dynamics for validating new control system. So this paper discusses about modeling and simulation of long term dynamics using RTDS. First, we build well known test system that consists of 2 generators and 11 buses using RTDS. Second, we model dynamic controllers and devices those are under load tap changer, over exciting limiter and dynamic load and we validate those dynamic characteristics. Those influence to long term voltage stability. Lastly, we simulate voltage collapse phenomena during long term time period using test-system include built long term dynamic models when occurring line fault.

Community pharmacists’ perceptions of dispensing long-term prescriptions exceeding 90 days – A survey of pharmacists from a single pharmacy chain

김윤정,홍은진,박혜경 한국임상약학회 2025 한국임상약학회지 Vol.35 No.2

The prevalence of long-term prescriptions, often exceeding six months, has increased in recent years. This raises concerns about potential risks to patient safety due to insufficient monitoring of changes in patient conditions after initiating treatment. Objectives: This study investigates community pharmacists’ perceptions of long-term prescriptions exceeding 90 days, focusing on dispensing practices, perceived advantages and disadvantages, and strategies to minimize associated risks. Methods: After informing 735 pharmacists from a single pharmacy chain about the study’s purpose and content, an online survey was conducted among those who consented to participate. A total of 267 pharmacists responded between July 6 and July 13, 2024. Data were collected using a Google Forms questionnaire and analyzed using chi-square tests with a significance level of 0.05. Results: 88.8% of pharmacists reported dispensing long-term prescriptions (≥90 days) daily, with 50-70% involving unit dose packing. Reduced patient visits and resulting cost saving were noted as benefits of long-term prescriptions. Concerns included risks such as decreased stability due to long-term storage, polypharmacy, reduced medication adherence, and drug waste. The main reasons for discarded medications were prescription changes (66.7%) and overlaps with other medications (26.2%). Conclusions: Long-term prescriptions can undermine the safety of drug use and lead to issues such as costs associated with drug disposal. Therefore, policy efforts are needed to address these concerns.

Long-term Chemical Stability Study for I Waste-form Using TAB (Te-Ag-Bi) Matrix in Domestic Underground Water

Hyeon Jin Eom,Ki Rak Lee,Ga yeong Kim,Kyuchul Shin,Hwan-Seo Park 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

During the treatment of spent nuclear fuel, radioactive iodine is generated in a liquefied or gaseous form in a specific process. In the case of iodine 129, it is a long-lived nuclide with a very long halflife and has high groundwater mobility under repository conditions. Despite showing a low radioactivity value, research on the management of radioactive iodine from a long-term perspective is continuously being performed. Although research has been conducted using borosilicate glass as a medium for solidifying iodine, compatibility of I in borosilicate glass is very small and the volatility is high in the solidification process. So it is not suitable as a solidified substance of iodine. Therefore, studies on other solidification media to replace them are continuously being conducted. Our research team tried to develop a new medium that can contain iodine in a solidified body stably through a simple heat treatment process and can improve problems such as volatility and waste loading. Iodine is captured as AgI in the Ag ion-exchanged zeolite. So, TeO2, Ag2O, and Bi2O3 having a high AgI loading rate were used as main components. It was named TAB after taking the first letter of each element. In previous studies, the physical properties, structure, and chemical stability of TAB materials were confirmed. PCT (Product Consistent test) was performed to confirm chemical stability. It is mainly used to compare the chemical stability of glass materials with other glass materials, but there are limitations in evaluating the long-term chemical stability of materials. In this experiment, we tried to evaluate the long-term stability of TAB and compare it with borosilicate, which is conventionally used to treat radioactive waste. In addition, we tried to understand the leaching behavior inside the TAB medium. For this purpose, ASTM C1308 test was performed for 365 days, and distilled water and KURT groundwater were used as leachates to examine the effect of ions in the groundwater on the solidified body. To analyze the leaching behavior, ICP-MS and ICP-OES analyses were performed, and the cross-section of the sample after leaching was observed through SEM.

가속노화를 이용한 매칭젤 장기 저장 영향성 평가 연구

남준식 한국산학기술학회 2024 한국산학기술학회논문지 Vol.25 No.7

Refractive index matching gel(매칭젤)은 분리된 광통신 케이블의 접촉면에 사용되어 통신 신호 감쇄를 방지하는 소재이다. 매칭젤은 군수품에 사용되어 장비의 정상적인 통신 유지를 보장하기 위해 사용된다. 군수품은 상용품과는 다르게 30년 이상 장기간 저장되며 장기 저장된 이후에도 유사시 정상 작동이 요구된다. 따라서 매칭젤은 높은 수준의 장기 안정성이 요구된다. 매칭젤은 주로 광섬유와 굴절률이 유사하고 안정성이 높은 실리콘 오일 소재로 만들어진다. 안정성이 높은 소재들로 매칭젤이 만들어지지만, 현재까지 장기 안정성에 관한 연구는 미흡하였다. 이 논문에서는 매칭젤의 장기 저장 안정성을 평가하고자 하였다. 매칭젤의 장기 저장 상태를 가속 노화 실험을 이용해 모사하고, 모사된 저장 기간에 따른 매칭젤의 원소 함량, 화학 작용기의 비율 변화 및 굴절률 변화를 관찰하였다. 매칭젤은 최대 265년 저장 기간이 모사되었다. 장기 저장 후 원소 비율과 화학적 조성은 크게 변하지 않으나, 굴절률이 특정 저장 기간 이후부터 증가하는 것을 관찰하였다. 이 연구 결과를 활용하면 매칭젤이 사용된 군수품의 장기 저장에 따른 통신계통 정비 주기 정립에 도움이 되어 군수품 신뢰성 향상에 이바지할 것으로 기대된다. Refractive index matching gel is used on the contact surface of separated optical communication cables to prevent the attenuation of communication signals. The gel is composed primarily of silicone oil, which closely matches the refractive index of optical fibers. In military applications, matching gels ensure the proper equipment functioning and maintain efficient communication. Nevertheless, the materials used need to exhibit high stability because of the complexity of military equipment and the requirement for long-term stability. Research on the long-term stability of these gels has been insufficient. This study evaluated the long-term storage stability of the refractive index matching gel. Thermal accelerated aging experiments simulated a storage duration of up to 265 years. The study showed that the elemental and chemical compositions were similar after long-term storage. On the other hand, an increase in refractive index is observed after a specific storage duration. These findings are expected to help establish maintenance cycles for military equipment that use a refractive index matching gel, enhancing their reliability in military applications.

Controlling the emulsion stability of cosmetics through shear mixing process

Kwang-Mo Kim,오희묵,이준협 한국유변학회 2020 Korea-Australia rheology journal Vol.32 No.4

The manipulation of emulsion stability for kinetically sustainable cosmetic emulsions is an important technology in cosmetic industry, however the relationship between emulsifying process and long-term emulsion stability has not been elucidated. Herein, the effect of shear mixing process on the stability of oil-in-water cosmetic emulsions is investigated by varying the shear mixing rate, emulsification time, and water phase temperature. The analysis on droplet size distribution and shear viscosity revealed that the strong viscous forces at optimal shear mixing rate of 4000 rpm afforded the fine and uniform droplets for cosmetic emulsions, leading to the improvement of long-term emulsion stability. Moreover, since the prolonged shear mixing induced the destabilization of emulsion droplets through droplet coalescence, optimal shear mixing time of 3 min could improve the kinetic stability of cosmetic emulsions. The dependence of long-term emulsion stability on emulsification temperature was relatively low. The theoretical analysis using the Derjaguin-Landau-Verwey-Overbeek theory demonstrated that the shear mixing rate played a major role in sustaining fine and uniform cosmetic emulsions with long-term stability. The present study can greatly contribute to the fabrication of functional cosmetic emulsions with long-term stability by controlling the shear mixing parameters in simple emulsification process.

군 초급장교의 직업안정성 및 복무활성화에 관한 연구 (육군3사관학교 출신 장기복무 관련 법령 및 제도개선 중심)

박동순 대한민국재향군인회 안보전략연구원 2024 재향군인회 안보전략연구 Vol.11 No.-

Korea Army Academy at Yeongcheon(KAAY) started as a short-term military academy in 1968, but since 1994, it has been a ‘transfer academy’ that commissions 3rd and 4th year cadets after training. In Korea, there is an emergency in recruiting entry-level executives due to the population cliff and shortened military service period. In particular, the application rate for cadets among officers from the KAAY is rapidly decreasing due to the burden of being selected for long-term service and the lack of job security, and the number of officers giving up after commissioning is also increasing. This study is about improving laws and systems to ensure job stability for employees from the KAAY, and was started with the purpose of contributing to the long-term securing of excellent resources. First, we recognized changes in the military service environment and analyzed equity issues in laws related to the KAAY and the long-term service status of graduates. Through this, the need to revise some of the relevant laws was presented. Additionally, improvements were made to related personnel management policies, including improvements in the human resources management system, such as long-term service selection. Through research, policy improvement directions were derived focusing on the necessity and justification for revision of the provisions related to long-term service selection in the 「Act on Establishment of the Korea Army Academy at Yeongcheon(KAAY)」 and the 「Military Personnel Management Act」. As a result of the study, in order to ensure job stability, long-term service selection laws and systems must be improved and the characteristics of the KAAY must be enhanced to contribute to the development of a strong military.

시설유형별 요양보호사의 직무만족도와 근무안정성과의 관계에서 자기효능감의 조절효과

유연서 동방문화대학원대학교 문화예술콘텐츠연구소 2023 문화와예술연구 Vol.23 No.-

This study examines the relationship between job satisfaction, self-efficacy, and work stability of nursing care workers in facilities related to the Long-Term Care Insurance Act for the Elderly, and in particular, compares and analyzes day and night care centers representing elderly care facilities and home-based elderly welfare facilities among related facilities. In order to ease the work stability of nursing care workers in facilities related to the Long-Term Care Insurance Act for the Elderly, we would like to present specific operational strategies to come up with measures to improve the professionalism of nursing care workers and secure stability in employment. This study conducted a self-written survey of 810 nursing care workers working at senior care facilities and home care welfare facilities in Seoul to analyze the moderating effect of self-efficacy on the relationship between job satisfaction and work stability of nursing care workers in each facility related to long-term care insurance for the elderly.Descriptive statistics, correlation analysis, and hierarchical regression analysis were conducted on the collected data, and the following conclusions were drawn. First, in the case of elderly care facilities, academic background and job satisfaction were found to have affected work stability, so efforts to increase work stability by education and intervention efforts to improve work stability for nursing care workers with low job satisfaction are needed.Second, job satisfaction was found to have a positive effect on work stability in both home-based welfare facilities and elderly care facilities, so job satisfaction should be improved to increase work stability of nursing care workers. Third, since there was a moderating effect of self-efficacy in the relationship between job satisfaction and work stability of nursing care workers by facility type, a program to improve self-efficacy is needed. Based on the conclusion of this study, it was suggested that programs to improve the level of job satisfaction and self-efficacy are needed to increase the work stability of nursing care workers in each facility related to long-term care for the elderly.

Long-term polarization stabilization of a polarization maintaining fiber via dynamic temperature control

Park Sanghyun,Baek Jaeuk,Lee Min-Hwan,Lee Sanglok,Moon Geol 한국물리학회 2025 Current Applied Physics Vol.72 No.-

We achieved long-term polarization stabilization of the output beam obtained from polarization-maintaining (PM) fiber by feeding heat back to the fiber. Optical polarization stability is crucial in various fundamental and engineering fields, particulary in a miniaturized field-deployable system composed of optical components, such as cold-atom-based quantum sensors. We constructed a feedback loop to stabilize the polarization of the output beam of a PM fiber in thermal contact with a Peltier element. Notably, a long-term polarization stability against thermal fluctuations was achieved, and the characteristics of the thermal polarization stabilizer were analyzed based on the power spectral density, Allan deviation, and Bode plots. The results indicate that this system can effectively serve as a long-term intensity stabilizer and is ideal for use in laboratories in which PM fibers are widely used, but exact temperature regulation is not feasible.

Long-term Stability of Conducting Polymers in Iodine/iodide Electrolytes: Beyond Conventional Platinum Catalysts

Kim, Sung June,Kwon, Jeong,Nam, Jae Keun,Kim, Wanjung,Park, Jong Hyeok Pergamon Press 2017 Electrochimica Acta Vol. No.

<P><B>Abstract</B></P> <P>One of the primary obstacles to the commercialization of dye-sensitized solar cells (DSSCs) is the improvement of their long-term stability. Here, we report greatly improved long-term stability of DSSCs, which have PEDOT:FTS polymer as a counter electrode. DSSCs with this PEDOT:FTS film demonstrate slightly lower power conversion efficiency of 8.1% under standard conditions (AM 1.5G, 100mWcm<SUP>−2</SUP>) compared to the ∼9.1% efficiency of Pt, using an electrolyte with iodine/iodide, which is the most popular redox shuttle. However, we demonstrate that this conducting polymer counter electrode facilitates the fabrication of solar cells with greatly improved long-term stability compared to Pt-based ones after exposure to electrolyte soaking conditions. Various electrochemical analyses were performed to evaluate the enhanced durability of PEDOT:FTS polymer in the highly corrosive iodine/iodide electrolyte under a continuous redox reaction condition.</P>

Stability of non-biofouling alginate/ZrIV coatings on Ti/TiO2 substrates

정연우,김인호,강성민 한국고분자학회 2024 Macromolecular Research Vol.32 No.1

Surface modification with alginate (Alg) has attracted significant attention because of its potential applications in nonbiofouling surface preparation, tissue engineering, and drug delivery. Much effort has been made to develop facile methods for preparing stable Alg coatings, including metal ion-mediated cross-link formation between polydopamine-coated solid surfaces and Alg. Although this approach has yielded Alg coatings that strongly inhibit platelet adhesion and fibrinogen adsorption on solid surfaces, their long-term stability, which is a prerequisite for practical applications, remains unknown. This study evaluated the long-term stability of Alg coatings under physiological conditions. The Alg coatings were incubated in phosphate-buffered saline at 37.5 °C for up to four weeks and subsequently analyzed for non-biofouling properties. The analysis revealed that the anti-protein adsorption and antiplatelet adhesion properties of the Alg coating were maintained at 80 and 90%, respectively, after four weeks of incubation. This study provides valuable insights into the long-term stability of Alg coatings and their potential for practical applications, addressing an overlooked crucial aspect. The findings contribute to advancements in tissue engineering, drug delivery systems, and other biomedical applications by enhancing our understanding of Alg coatings' durability and guiding the design of robust non-biofouling materials.