• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.662-669
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• 2014

Mineral oil has been widely used as dielectric insulating fluid in transformers due to its excellent performance in-service. However, there are few issues with mineral oil such as it has poor biodegradability and could contaminate the environment if a spillage occurs. With the increasing tight regulation on safety and environment, alternative fluids for mineral oil are currently being investigated and among the suitable candidate is the vegetable oil. There are different types of vegetable oils and one of them is the palm based oil. At the moment, extensive research works are carried out to examine its feasibility to be applied in transformers. This paper will review the previous research works that were carried out to examine the suitability of palm based oil as dielectric insulating fluid in transformers. The physical and chemical properties of palm based oil are studied based on viscosity, acidity, oxidation stability and flash point. Next, the electrical characteristics of palm based oil are examined based on AC breakdown voltage, relative permittivity, dissipation factor and partial discharge.

• 지식경영연구
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• 제20권2호
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• pp.105-135
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• 2019

This study investigates cognitive and emotional changes in individuals to clarify the principle between artistic stimulation and business innovation idea generation based on phenomenological research methodology. We conducted in-depth interviews with six participants who participated in the artistic creation program of business art, and derived meanings from their experience. As a result, we presented 4 essential categories, 8 main subjects, and 20 sub-subjects; 1) Optimizing rational and creative thinking, 2) Projecting oneself to the artist, finding balance, 3) Having room in mind to view the surroundings, finding insight into the world, 4) Eureka moment, crossing the boundary between business and art. We also found out participants of the program 1) Gradually expanded the criteria, 2) In chaotic directions, and 3) Leaded business creativity through from a non-form to reality throughout the project experience, The attempt to identify business phenomena by using phenomenological qualitative research methods had an academic significance regarding the unfamiliarity of the method in the business administration area. Moreover, this study broadened the possibility of promoting creativity by art in business areas. The study verified the categories and subjects of the business art, paving the way towards application in the real business situation.

• Structural Engineering and Mechanics
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• 제69권1호
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• pp.1-10
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• 2019

In the construction of flat plate slabs, which are widely used for tall buildings but have relatively low flexural stiffness, serviceability problems such as excessive deflections and cracks are of great concern. To prevent excessive deflections at service load levels, current design codes require the minimum slab thickness, but the requirement could be unconservative because it is independent on loading and elastic modulus of concrete, both of which have significant effects on slab deflections. In the present study, to investigate the effects of the construction load of shored slabs, reduced flexural stiffness and moment distribution of early-age slabs, and creep and shrinkage of concrete on immediate and time-dependent deflections, numerical analysis was performed using the previously developed numerical models. A parametric study was performed for various design and construction conditions of practical ranges, and a new minimum permissible thickness of flat plate slabs was proposed satisfying the serviceability requirement for deflection. The proposed minimum slab thickness was compared with current design code provisions and numerical analysis results, and it agreed well with the numerical analysis results.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.668-669
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• 2016

상용차에 장착된 리타더(retarder)는 상용 브레이크를 보조하는 유압식 브레이크 시스템으로써 운전자의 자동모드 및 수동모드 선택에 의해 작동된다. 리타더 작동에 의해 발생된 열은 리타더 오일에 전달되며 리타더의 냉각기와 차량의 냉각시스템에 의해 열교환이 일어난다. 이때 리타더의 ECU는 자동모드와 수동모드, 리타더 오일/냉각수 온도, 엔진 냉각수 온도, 차량속도 등을 고려하여 제동토크를 조정하는 기능을 수행한다. 본 논문에서는 냉각 시스템 관련 리타더 제어로직 설계와 리타더 제동성능에 따른 시험결과를 제시하고자 한다.

• 한국해양공학회지
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• 제33권2호
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• pp.196-202
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• 2019

In this study, the excessive noise and vibration phenomena of a high-speed Ro/Ro passenger ship were analyzed, and a countermeasure was taken based on them. This ship was granted a comfort class notation by the classification society, which was COMFORT-VIBRATION-II and COMFORT-NOISE-CREW-II. However, unfortunately, excessive noise and vibration in the aft part of the ship were delivered from the twin shaft propellers, and therefore the Class Requirement was not satisfied before delivery. In order to obtain the class notation, all of the concerned parties came to an agreement to reduce the noise and vibration level during operation after delivery because a seasonal ferry service was already scheduled and the cabin was fully booked. The root cause of the massive amount of noise and vibration was mainly the propeller-induced excitation pulse and beating that occurred from the mismatch of the rotating speeds of the two shaft lines. A 1st order vibrating force and beating phenomena existed in the propeller. Thus, a reduction of the excitation force, elimination of the beating phenomena, and decrease of the noise level at the aft area cabins and public spaces were required. In addition, structural reinforcements were conducted using pillars and additional girders at the aft part of the decks.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.297-307
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• 2021

In the vibrant environment, documentation and managing systems are maintained autonomously through education foundations, book materials and libraries at the same time as information are not voluntarily accessible in a centralized location. At the moment Libraries are providing online resources and services for education activities. Moreover, libraries are applying outlets of social media such as Facebook as well as Instagrams to preview their services and procedures. Librarians with the assistance of promising tools and technology like analytics software are capable to accumulate more online information, analyse them for incorporating worth to their services. Thus Libraries can employ big data to construct enhanced decisions concerning collection developments, updating public spaces and tracking the purpose of library book materials. Big data is being produced due to library digitations and this has forced restrictions to academicians, researchers and policy creator's efforts in enhancing the quality and effectiveness. Accordingly, helping the library clients with research articles and book materials that are in line with the users interest is a big challenge and dispute based on Taibah university in Saudi Arabia. The issues of this domain brings the numerous sources of data from various institutions and sources into single place in real time which can be time consuming. The most important aim is to reduce the time that lapses among the authentic book reading and searching the specific study material.

• The Journal of Advanced Prosthodontics
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• 제13권3호
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• pp.172-179
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• 2021

Purpose. This intra-patient retrospective study of up to 10 years evaluated the clinical success and risk factors of 6- and 8-mm long implants and their respective prostheses. Materials and Methods. The sample consisted of patients treated at a Military Polyclinic dental service, who received both 6- and 8-mm long tissue level implants in the posterior region of the same arch. Data were collected from the dental charts, clinical and radiographic exams, self-report of sleep bruxism, measurement of maximum occlusal force, and clinical crown-to-implant (C/I) ratio. Data were analyzed by descriptive and inferential statistics with univariate and hierarchical multivariate models, at the 0.05 significance level. Results. The 30 patients (27 women) had 85 implants and 83 prostheses. Two implants were lost before prosthesis installation (implant survival: 97.6%). Ten events of prosthetic complication (screw tightening loss) occurred in five patients (success rate: 87.9%) in a single moment. Only the variable C/I ratio had a significant effect for repairable prosthesis complication (P<.05). Conclusion. The results suggest that 6- and 8-mm long implants have similar long-term clinical success for implants and prostheses.

• 대한건축학회논문집:계획계
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• 제35권4호
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• pp.15-24
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• 2019

Currently, museums and architectural heritage provide augmented user experiences by incorporating various media technologies. They still, however, suffer from the limitation of entertainment-based and the provision of location-based simple and repetitive contents. In addition, while acting as a key medium of experience for architectural heritage, the concept of space is not properly reflected in current services. The purpose of this study is to design user space experience considering such characteristics of architectural heritage. The spatial experience content and content production platform are defined. This software platform creates content that enhances the experience of the place by giving a context-based digital data associated with space and objects. The spatial experience content is designed as a series of experience sequences. The composition of the sequence borrows the method of film and narrative which segment and connect consecutive experiences on a scene basis considering user's detailed spatial experience. Therefore, content components can be combined and reproduced in various types. Augmented contents were extracted by using rule-based reasoning function of ontology at the moment. As a practical example of architectural heritage, the Seokjojeon Hall is used to reveal a spatial experience scenario.

• 융합보안논문지
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• 제20권5호
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• pp.75-80
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• 2020

지난해에 이어 랜섬웨어로 인한 피해가 계속 증가되고 있으나 군내 사이버작전 수행지침에 별도의 랜섬웨어 유형 분류없이 사이버 작전 상황을 관리하고 있는 실정이다. 그러나 랜섬웨어는 다른 악성코드와 달리 조치내용과 파급력을 고려할 때, 한 순간 모든 국방업무를 마비시킬 수 있는 위협요소로 군은 랜섬웨어를 재평가하고 이에 따른 대비책을 강구해야 한다. 이에 따라 본 논문에서는 정보보안 위험관리 기반의 국방정보화 관련 자산, 취약점, 위협 등을 분석하고, 랜섬웨어 위협으로부터 국방업무의 연속성을 확보하기 위한 대안을 제시하고자 한다.

• Structural Monitoring and Maintenance
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• 제10권3호
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• pp.221-242
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• 2023

Internal and external corrosion are common in pressure pipes used in a variety of industries, often resulting in defects that compromise their integrity. This economically and industrially significant problem calls for both preventive and curative technical solutions to guarantee the reliability of these structures. With this in mind, our study focuses on the influence of composite and metallic patch repairs on the limit loads of pipes, particularly elbows, the critical component of piping systems. To this end, we used the nonlinear extended finite element method (X-FEM) to study elbows, a priori corroded on the internal surface of the extrados section, then repaired with composite and metallic patches. In addition, the effect of the geometry of composite materials and metal patches was examined, in particular the effect of their thickness and material on the increase in limit loads of repaired structures. The results obtained provide information on the effectiveness and optimization of patch repair of corroded elbows, with the aim of increasing their service life.