• Title/Summary/Keyword: External connection method

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Voltage Control of Power System Connected to a Wind Farm by Using STATCOM and Reactive Power Compensators (STATCOM과 조상설비를 이용한 풍력단지가 연계된 전력계통의 전압제어)

  • Seo, Gyu-Seok;Park, Ji-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.4
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    • pp.2737-2743
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    • 2015
  • The wind power plant must be able to produce reactive power at the POI bus of a wind farm connected to power system to keep or control the voltage of POI bus. But, the reactive power capability of wind turbines may not be sufficient to control the voltage of POI bus due to the reactive power losses in connection lines between wind farm and POI bus. The solution of this problem is to install an external STATCOM. The proposed cooperative control method of STATCOM and conventional reactive power compensators such as Switched-shunt and tap changing transformer can control the voltage of POI bus more efficiently. The simulation results are shown that the voltage drop of POI Bus of Test System with the arbitrary load change rate to initial loads is improved more than 60% and the voltage of load bus is maintained more than 95% of rated voltage.

A Study on the Service Method of Modern Literature Based on Linked Data (링크드 데이터 기반 근대문학자료의 서비스 방안 연구)

  • Park, Jin-Ho;Kwak, Seung-Jin
    • Journal of the Korean Society for Library and Information Science
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    • v.55 no.2
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    • pp.5-24
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    • 2021
  • This study suggested a plan to convert the modern literary data service of the National Library of Korea into linked data-based services. This is not to simply convert the modern literary data service into linked data, which is the current technological trend. This is to create high-quality source data capable of automated machine processing with continuous connection with various external data and information sources in the long term. To this end, in order to revitalize the service of modern literature and to solve the efficient data linkage with related institutions, various overseas library and bibliographic service cases that adopted linked data were first reviewed to draw implications. In addition, based on the reviewed implications, the plan to reorganize the modern literary service in terms of data management, system management, and user service was described in detail.

Simultaneous Reconstruction of a Subtotal Maxillectomy and Columella Deficit using Radial Forearm and Preauricular Free Flaps (요측전완과 이개전부 유리피판을 이용한 아전상악절제술과 비주결손의 동시 재건)

  • Yoon, Taekeun;Eun, Seokchan;Cho, Sung-Woo;Rhee, Chae-Seo
    • Korean Journal of Head & Neck Oncology
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    • v.38 no.1
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    • pp.53-57
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    • 2022
  • Reconstruction of subtotal maxillectomy defects with columella deficit is challenging. We report a unique case of facial reconstruction using a free radial forearm flap and a free preauricular flap for the maxillectomy and columella deficit. A 73-year-old woman was diagnosed with recurrent sebaceous carcinoma of the nose. We performed wide excision, including areas of the right cheek, nose, upper lip, maxilla, and columella. The resultant subtotal maxillectomy defect was reconstructed using a three-dimensional flap. First, a free radial forearm flap was transfered to resurface the nasal, oral, and external facial side. Second, a preauricular flap was positioned into the columella defect and anastomosed with the distal portion of the radial forearm flap pedicle. The two flaps survived, and the patient recovered uneventfully. We believe the radial forearm and preauricular double free flaps with the pedicle connection method were effective in reconstructing the present case of subtotal maxillectomy defect.

Feasibility of UHPC shields in spent fuel vertical concrete cask to resist accidental drop impact

  • P.C. Jia;H. Wu;L.L. Ma;Q. Peng
    • Nuclear Engineering and Technology
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    • v.54 no.11
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    • pp.4146-4158
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    • 2022
  • Ultra-high performance concrete (UHPC) has been widely utilized in military and civil protective structures to resist intensive loadings attributed to its excellent properties, e.g., high tensile/compressive strength, high dynamic toughness and impact resistance. At present, aiming to improve the defects of the traditional vertical concrete cask (VCC), i.e., the external storage facility of spent fuel, with normal strength concrete (NSC) shield, e.g., heavy weight and difficult to fabricate/transform, the feasibility of UHPC applied in the shield of VCC is numerically examined considering its high radiation and corrosion resistance. Firstly, the finite element (FE) analyses approach and material model parameters of NSC and UHPC are verified based on the 1/3 scaled VCC tip-over test and drop hammer test on UHPC members, respectively. Then, the refined FE model of prototypical VCC is established and utilized to examine its dynamic behaviors and damage distribution in accidental tip-over and end-drop events, in which the various influential factors, e.g., UHPC shield thickness, concrete ground thickness, and sealing methods of steel container are considered. In conclusion, by quantitatively evaluating the safety of VCC in terms of the shield damage and vibrations, it is found that adopting the 300 mm-thick UHPC shield instead of the conventional 650 mm-thick NSC shield can reduce about 1/3 of the total weight of VCC, i.e., about 50 t, and 37% floor space, as well as guarantee the structural integrity of VCC during the accidental drop simultaneously. Besides, based on the parametric analyses, the thickness of concrete ground in the VCC storage site is recommended as less than 500 mm, and the welded connection is recommended for the sealing method of steel containers.

Identification of Internal Resistance of Microbial Fuel Cell by Electrochemical Technique and Its Effect on Voltage Change and Organic Matter Reduction Associated with Power Management System (전기화학적 기법에 의한 미생물연료전지 내부저항 특성 파악 및 전력관리시스템 연계 전압 변화와 유기물 저감에 미치는 영향)

  • Jang, Jae Kyung;Park, Hyemin;Kim, Taeyoung;Yang, Yoonseok;Yeo, Jeongjin;Kang, Sukwon;Paek, Yee;Kwon, Jin Kyung
    • Journal of Biomedical Engineering Research
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    • v.39 no.5
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    • pp.220-228
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    • 2018
  • The internal resistance of microbial fuel cell (MFC) using stainless steel skein for oxidizing electrode was investigated and the factors affecting the voltage generation were identified. We also investigated the effect of power management system (PMS) on the usability for MFC and the removal efficiency of organic pollutants. The performance of a stack microbial fuel cell connected with (PMS) or PMS+LED was analyzed by the voltage generation and organic matter reduction. The maximum power density of the unit cells was found to be $5.82W/m^3$ at $200{\Omega}$. The maximum current density was $47.53A/m^3$ without power overshoot even under $1{\Omega}$. The ohmic resistance ($R_s$) and the charge transfer resistance ($R_{ct}$) of the oxidation electrode using stainless steel skein electrode, were $0.56{\Omega}$ and $0.02{\Omega}$, respectively. However, the sum of internal resistance for reduction electrode using graphite felts loaded Pt/C catalyst was $6.64{\Omega}$. Also, in order to understand the internal resistance, the current interruption method was used by changing the external resistance as $50{\Omega}$, $300{\Omega}$, $5k{\Omega}$. It has been shown that the ohm resistance ($R_s$) decreased with the external resistance. In the case of a series-connected microbial fuel cell, the reversal phenomenon occurred even though two cells having the similar performance. However, the output of the PMS constantly remained for 20 hours even when voltage reversal occurred. Also the removal ability of organic pollutants (SCOD) was not reduced. As a result of this study, it was found that buffering effect for a certain period of time when the voltage reversal occurred during the operation of the microbial fuel cell did not have a serious effect on the energy loss or the operation of the microbial fuel cell.

Studies on AIDS(Acquired Immune Defficiency Syndrome) Preventive Educational Programs Intended for Domestic and Foreign Industrial Workers (국내외 산업장 근로자의 AIDS(Acquired Immune Deficiency Syndrome)예방교육을 위한 소고)

  • Jung Moon-Hee;Cho Chung Min
    • Journal of Korean Public Health Nursing
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    • v.10 no.1
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    • pp.12-22
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    • 1996
  • Currently. exchanges of industrial workers between countries are more active than ever. and the problem of AIDS in connection with the operation of preventive educational programs has reached a point where the issue cannot be limited to native people alone any more. Based on such judgement. this research has been carried out to provide basic study materials by grasping the latent factors representing the difference between countries in the levels of right knowledge. attitude and behavior with respect to AIDS maintained by workers who have grown in different social and cultural living background. During the period from Apr. 1. 1995 to Jun. 30. questionnaires. written both in Korean and English, were distributed to Korean and Malaysian employees working at certain Korean video manufacturers. and the results of replies. given by 80 workers who were analyzed through matched sampling· method where ages and sex matched by country. were used as the research materials. The gathered materials were analyzed through the SPSS package t-test. ANOVA. factor analysis and multiple stepwise regression methods. and the following results were obtained. 1. The 2 extracted latent factors could be named 'common. social' knowledge factor and 'in-depth. psychological' knowledge factor respectively. 2. The percentile points of 'external. social' knowledge factor. in the case of Korean workers. howed 90.0 at average. a figure 13.75 points higher than those of Malaysian workers. 76.25. On the other hand. the percentile points of the 'in-depth. psychological'knowledge factor showed 70.80 at average in the case of Korean workers. a figure 7.47 points lower than those of Malaysian workers. 78.33. Meanwhile. the difference in percentile points between the 2 latent factors was 8.54 at average. indicating that the points of 'in-depth. psychological' knowledge factor was lower than those of the 'external. social' knowledge factor. 3. As for Korean workers. the percentile points of the 'in-depth. psychological' knowledge factor showed higher points in office workers than in non-office workers. and such variables exhibited in the position of workers can explain the $7\%$ of the latent factor. The percentile points of the 'in-depth. psychological' knowledge factors. in the case of Malaysian workers. showed higher points in groups who had religion than in groups who did not. and higher points in groups who obtained information from newspapers than in groups who obtained from televisions or other sources; and with these 2 variables. $26\%$ of this latent factor can be explained. The results. of analysis described so far suggest that while Korean workers possessed general level of knowledge on AIDS. they had low level of practical knowledge as far as its depth is concerned. and that they had social prejudice on patients as well as on the AIDS infection route. In addition. because the overall knowledge level of Malaysian workers. is lower than that of Korean workers. it suggests that separate programs intended for Malaysian workers are required prior to executing integrated programs.

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A Study on Desing Simplification of Yoke Crank in a γ-type Stirling Engine (γ-type Stirling Engine의 Yoke crank 설계 단순화에 관한 연구)

  • Kim, Shin-Hyo;Kim, Ui-Chang;Bark, Jin-Jae;Bae, Han-Nah;Cho, Dae-Kweon
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.4
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    • pp.405-411
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    • 2015
  • Recently, according to the low-carbon green growth policy, the Stirling Engine has been increasing the interest of some sort of external combustion engines Stirling Engine is largely divided into three types ${\alpha}$, ${\beta}$ and ${\gamma}$. Among them, a ${\gamma}$-type engine is easy to design and can be applied variously. However, owing to the connection distance between the cylinder and the crank, there was a problem that ${\gamma}$-type occupies a larger volume than the ${\alpha}$ and ${\beta}$-types. As one of the methods to solve this problem, we have to consider about the Yoke crank which have been applied mainly to the ${\alpha}$-type. Because there are two advantages in not only reduction of engine volume but also parallelizing the cylinder. In this study, leading on from the existing design techniques for the Ross Yoke crank, this paper presents a simple method that can apply the yoke crank design of the ${\gamma}$-type stirling engine.

Quality Improvement in Patient Care Services : Obstacles and Approaches (진료의 질관리에 대한 시론 -장애와 접근-)

  • 한달선
    • Health Policy and Management
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    • v.2 no.2
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    • pp.112-130
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    • 1992
  • Patient care services are provided to individual patients in response to their health needs produced by illnesses or injuries. The services are often addressed to very serious conditions, and also they constitute the most expensive component of health care services. Therefore, the importance of quality is emphasized, but there are many indications that patient care quality is far from a satisfactory state in most of the countries. Based upon this observation, it is attempted to examine obstacles and approaches to quality improvement in patient care services. In doing so, following Taguchi's(1986) definition of product quality, quality of patient care services is conceived of as better when the less is the sociental loss attributalbe to variability of intended function and harmful side effects they emhibit after being delivered. Some distinguishing features of medical care sector pose difficulties in implementing effective quality improvement programs in patient care services. Nevertheless, newly proposed method of quality management, based on industrial quality management approach, seems to have a great deal of potential to effectively cope with such difficulties. This method, unlike the traditional approach to quality assurance, focuses on total organisational processes, not individuals, as the obproach to quality assurance, focuses on total organizational processes, not individuals, as the objects of quality improvement; variation, not comparison with standards, in quality measurement; and continuous improvement, not removing only bad quality care, as an ideal. Prerequisite to a successful use of any quality mangement method is motivating providers to improve quality. Conceivable approaches for such motivation are self-regulation, external controls and promotion of competition. Since these approaches are not mutually exclusive, they may be employed in an appropriate combination. In Korea, medical care providers are now functioning under the circumstances where they have little reason for making efforts to improve quality of their services. Once these circumstantial conditions are changed to exert pressures on providers to improve quality, the use of adequate quality management method becomes an issue. In this connection, much attention shoould be directed to the newly proposed method described above. In all these efforts for improving quality of patient care services, health insurance would be able to play a pivotal role. Poviders of medical care, buth indiciduals and organizations, are usually very responsive to the measures that affect their financing, and thus health insurance can be a strong instrument for motivationg providers to improve quality. Also, the insurance continuously acquires data on patient care, which could be processed to produce information required to effective quality control.

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Development of Precast Concrete Method for Eco-Pillar Debris Barrier with Hollow Cross-Section (중공트랙형 단면의 프리캐스트 에코필라 사방댐 공법개발)

  • Kim, Hyun-Gi
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.3
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    • pp.542-552
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    • 2018
  • In this paper, the precast method of a concrete eco-pillar debris barrier was proposed to improve the construct ability and economic efficiency. The performance was validated by experimental and structural analysis. The steel debris barrier has a high construction cost and causes environmental damage with corrosion. The construction of a concrete eco-pillar debris barrier has been increased recently. On the other hand, there are no design standards regarding debris barriers in Korea, and debris barriers are being designed by the experience and sense of engineers. Therefore, in this study, a method to determine the design external forces was proposed and the design was performed by applying a hollow cross-section to the debris barrier. In addition, three types of connection methods of a concrete cantilever column with the maximum bending moment acts were proposed, and validation of the performance of each type was performed with a real-scale experiment. The experimental results showed that the type with loop reinforcement had the highest rigidity and the type with anchorage performance exceeded the maximum bending moment according to the ultimate load. In the manufacturing procedure of mock-up debris barriers, the type with an anchorage-bar was found to have superior construct ability.

Success rate and marginal bone loss of Osstem USII plus implants; Short term clinical study (Osstem USII plus 임플란트의 단기간 성공률 및 변연골 흡수량 평가)

  • Kim, Sun-Keun;Kim, Jee-Hwan;Lee, Keun-Woo;Cho, Kyoo-Sung;Han, Dong-Hoo
    • The Journal of Korean Academy of Prosthodontics
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    • v.49 no.3
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    • pp.206-213
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    • 2011
  • Purpose: The aim of this study was to evaluate the clinical value of Osstem$^{(R)}$ USII plus system implants. Clinical and radiographic data were analyzed for 88 implants placed and functionally loaded for a 12 month period at the Yonsei University Dental Hospital. Materials and Method: Based on the patient's medical records, clinical factors and their effects on implant marginal bone resorption, distribution and survival rate were analyzed. The marginal bone loss was evaluated at implant placement and during a 6 to 12 months functional loading period. The independent sample t-test was used to evaluate the interrelationship between the factors (${\alpha}$=0.05), and one way repeated measures ANOVA was used to compare the amount of marginal bone resorption. Results: The cumulative survival rate for 88 implants was 100%. The marginal bone resorption from implant placement to prosthetic delivery was 0.24 mm and the average marginal bone resorption from prosthetic delivery to 12 months of functional loading was 0.19 mm. The total average bone resorption from implant placement to 12 months of functional loading was 0.43 mm. There were no statistically differences in the amount of marginal bone resorption when implants were placed in the maxilla or the mandible (P>.05), however, implants placed in the posterior areas showed significantly more marginal bone loss than those placed in the anterior areas (P<.05). Conclusion: Based on these results, the short term clinical success rate of RBM surface treated external connection domestic implants showed satisfactory results and the marginal bone loss was in accord with the success criteria of dental implants.