• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.262.2-262.2
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• 2014

Plasma processing is an essential process for pattern etching and thin film deposition in nanoscale semiconductor device fabrication. It is necessary to maintain plasma chamber in steady-state in production. In this study, we determined plasma chamber state with residual gas analysis with self-plasma optical emission spectroscopy. Residual gas monitoring of fluorocarbon plasma etching chamber was performed with self-plasma optical emission spectroscopy (SPOES) and various chemical elements was identified with a SPOES system which is composed of small inductive coupled plasma chamber for glow discharge and optical emission spectroscopy monitoring system for measuring optical emission. This work demonstrates that chamber state can be monitored with SPOES and this technique can potentially help maintenance in production lines.

• Journal of the military operations research society of Korea
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• v.4 no.1
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• pp.113-123
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• 1978

Consider a series system of two units, named 1 and 2, respectively. Two units are observed at the beginning of discrete time periods t=0,1,2, $cdots$ and classified as being in one of a countable number of states. Let (i, r) be a state of the system at time t, when the state of unit 1 is i and state of unit 2 is r at time t, Under some conditions, the opportunistic replacement policy that minimizes the expected total discounted cost or the average cost of maintenance is shown to be characterized by the control limits $i^{*}(r)$ (a function of r) and $r^{*}(i)$ (a function of i) : (a) in observed state (i, r), the optimal policy for unit 1 is to replace if $i{\ge}i^{*}(r)$ and no action otherwise; (b) in observed state (i, r), the optimal policy for unit 2 is to replace if $r{\ge}r^{*}(i)$ and no action otherwise. In addition, this paper also develops optimal policy in the finite time horizon case, where time horizon is fixed or a finite integer valued r.v. with known pmf.

• International Journal of Knowledge Content Development & Technology
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• v.14 no.4
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• pp.85-99
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• 2024

The study examined perception of library personnel towards social media utilization for information service delivery in kwara state university library. It adopted the descriptive survey design with population consisting of 27 professional librarians in three selected university libraries in kwara State. Total enumerative sampling techniques were used because the population of the study is manageable by the researcher. Percentage and mean were used in analyzing the data. Primary data solicited would be cleaned, coded and entered into the Statistical Package for Social Sciences (SPSS) version 20 software for quantitative analysis. The findings of the study revealed the services rendered by library professional in university libraries in Kwara State, are Current Awareness Services (CAS), Photocopying services, Technical Services, Circulation/borrowing services, Internet services, and Bibliographic verification services. Majority of the respondent indicated Myspace, Google plus, Flickr, Telegram, Twitter, WhatsApp and Facebook are the social media platforms used for service delivery by librarians. Also, majority of the respondents in university libraries indicated Google plus, LinkedIn, Myspace, Skype, WhatsApp, Flickr, WeChat, Twitter and Facebook as social media space use for information service delivery effectively and Bandwidth problem, Limited fund, Lack of maintenance culture, Lack of Awareness, Copyright Issue, Technophobia are the major challenges inhibiting the use of social media for service delivery by the library staff. Lastly, the study concluded with recommendations.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1367-1379
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• 2015

A hybrid HVDC system that is composed of line commutated converter (LCC) at the rectifier side and voltage source converter (VSC) in series with LCC at the inverter side is studied in this paper. The start-up strategy, DC fault ride-through capability, and fault recovery strategy for the hybrid HVDC system are proposed. The steady state and dynamic performances under start-up, AC fault, and DC fault scenarios are analyzed based on a bipolar hybrid HVDC system. Furthermore, the immunity of the LCC inverter in hybrid HVDC to commutation failure is investigated. The simulation results in PSCAD/EMTDC show that the hybrid HVDC system exhibits favorable steady state and dynamic performances, in particular, low susceptibility to commutation failure, excellent DC fault ride-through, and fast fault recovery capability. Results also indicate that the hybrid HVDC system can be a good alternative for large-capacity power transmission over a long distance byoverhead line.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2007.10b
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• pp.118-126
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• 2007

Seoul has been the former capital from Joseon founded in 1932 by this time for 600 years. Seoul populated by some 10,290,000 people is the largest city in Korea. There are lots of cultural inheritance such as the castle town and 5 palaces including Gyeongbokgung in Seoul. Especially neungs(royal tombs) from 27 generations of king and queen in the Joseon dynasty during 518 years are very important cultural inheritance. The royal tombs were built from the castle town to the radius outside 4km within 40km pivoting on Seoul. Joseon royal tombs might have significant cultural value, which are representative Korean people's spirits for ancestor worship. After the 1945 Liberation of Korea those are having been managed by Office of Cultural Properties after Ministry of Education. This paper tried to find the changing process of the conservation and maintenance, the location of royal tomb area, the changing process of royal tomb, the area changing clue of modernization process, and in the historical city, Seoul. The royal tombs in the Joseon dynasty of the radius outside 4km within 40km pivoting on Seoul have been contributed to providing the metropolitan, Seoul population with the cultural and green spaces for 600 years. In the Joseon dynasty the royal tombs had been taken charge of thoroughly by the Royal Household with Neungchamboing system from Confucian background for ancestor worship. There after they had been damaged somewhat by the Japanese Imperialism period, the Korean War, and the pressure of urbanization. But the original state has been preserved well by state management. The royal tombs in the Joseon dynasty has been kept the culture of royal tomb's and memorial services with stone sculptures for 518 years. Also there are lots of documentary records of royal tombs. The memorial services of the tombs are held by Jongyakwon of Jeonju Lee family every year. The royal tombs somewhat damaged are needed to the original state of the transferred right of managing agency by the related national bodies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.1-10
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• 2022

For the composite section of corrugated steel sheet and concrete, which is often used in soil structures, a conservative design method based on the ultimate strength state is still applied due to the difficulty of the analysis of compatibility condition. In this study, plastic analysis was performed on the flexural and axial strength of the composite section using two limit state design methods, LRFD and LSD. As a result of the analysis of the experimental results, the LRFD analysis value was interpreted as a conservative results for compressive strength, and it was analyzed that the effect of the concrete compressive strength was greater than the steel ratio of the steel plate. The flexural strength was analyzed to be in good agreement with the experimental results by the LSD analysis. From the parametric analysis on the design variables, the hogging moment, which is affected by the tensile strength of the steel plate, slightly decreased the increasing rate of the strength due to the influence of the bolts connection, but the sagging moment linearly increased according to the increment of steel reinforcement ratio.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.47-53
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• 2014

The paper investigates the limit state of deflection for short and medium span steel girder bridges. Deflection depends on stiffness of steel girders and integrity of the reinforced concrete slab (composite action). Load and resistance parameters are treated as random variables. A probabilistic model is developed for prediction of the deflection. The structural performance can be affected by deterioration of components, in particular corrosion of steel girders. In addition, the creep of concrete can greatly influence the deflection of composite structures. Therefore, the statistical models for creep and corrosion of structural steel are incorporated in the model. Structures designed according to the AASHTO LRFD Code are considered. Load and resistance models are developed to account for time-variability of the parameters. Monte Carlo simulations are used to estimate the deflections and probabilities of serviceability failure. Different span lengths and girder spacing are considered for structures designed as moment-controlled and deflection-controlled. A summary of obtained results is presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.1-10
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• 2013

Probabilistic nonlinear first ply failure loads of flat composite panels and nonlinear buckling loads of curved composite panels with cutouts are estimated to provide the more reliable main load carrying structure in the renewable energy industry and offshore structures. The response surface method approximates limit state surface to a second order polynomial form of random variables with the results of deterministic finite element analyses at given sampling design points. Furthermore, the iterative linear interpolation scheme is used to obtain a more accurate approximation of the limit state surface near the most probable failure point (MPFP). The advanced first order second moment method and the Monte Carlo method are performed on an approximated limit state surface to evaluate the probability of failure. Finally, the sensitivity of the reliability index with respect to transformed random variables is investigated to figure out the main random variables that have an effect on failures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.55-63
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• 2012

This paper presents materials and processing technique to manufacture low viscous strain-hardening cementitious composite which is suitable for structures requiring low viscosity of materials. The micromechanics and fracture mechanics tools coupled with processing techniques were adopted to achieve low viscosity of composites as well as high tensile strain capacity. Optimal volume and length of fibers and interfacial properties between fibers and matrix for composites with tensile strength of 2~3MPa were determined on the basis of the micromechanical analysis and the steady-state cracking theory. Then six mixtures were determined and the experiment was carried out to evaluate the viscosity and uniaxial tensile performance of those. From the test results, it is verified that the strain-hardening cementitious composite with low viscosity suitable for grouting applications in fresh state as well as high ductility over 1.5% in hardened state can be feasible.

• Journal of Korean Academy of Nursing
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• v.24 no.1
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• pp.70-84
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• 1994

People experience health behaviors for themselves and theses have diversity according to each culture and people and further there is an inherent meaning in health behavior The purpose of this study was to explore the health cconcept of Korean people and their pattern of health behavior The research method was a questionaire including open questions and the subjests were 164 adults age from 21 to 61. The result of this study are as follows : 1. Perceived health concepts by adults were “possibility”, “responsibility”, “being free”, “happiness”, “brightness”, “power”, “life”, “importance”, “mental rest”, “state of nnonilliness”, “death” 2. Health behaviors carried out by Korean adults were “maintance of psychological comfort”, “exercise”, “work”, “maintance of balanced diet”, “having a hobby”, “eating health food”, “health check up”, “prevention of hazards”, “eating natural food”, “maintenance of personal relationships”, “rest”, “having religion”, “making contract with nature”, “relaxation”, “limit one’s tastes”. 3. The perceived purposes of health behavior by Koran adults were maintenance of a joyful life, health maintenance, health restoration, prevention of illness, achievement of reponsibility, haying a hobby, longevity, peaceful death. Korean health concepts in this study showed a trend that reflects the rule of family and forcused harmony and eating habits. Korean health behavior in this study showed a trend that forcuses on emotional comfort which reflects oriental thinking. The result of this study will contribute to build a theory of health behavior and to derive strategies of health behavior to promote health.