• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.556-557
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• 2014

This paper presents an artificial intelligence - Deep Belief Network (DBN) gain-scheduling adaptive PI controller scheme for dual active bridge (DAB) converter. The PI gains are allowed to vary within a predetermined range and therefore eliminate the problems faced by the conventional PI controller. The performance of the proposed controller is simulated and compared with the conventional fixed PI controller under various conditions. The experimental prototype of the DAB converter is implemented using a digital signal processor of TMS320F28335 manufactured by Texas Instrument to examine and to evaluate the performance criteria of the proposed controller. Simulation and experimental results show improvements in transient as well as steady state responses of the proposed controller over the conventional fixed PI controller.

• 한국산업융합학회 논문집
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• 제26권4_1호
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• pp.545-551
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• 2023

In this paper, a robot automation methodology for chemical drum assembly in semiconductor industries are presented. Robot automation is essential to resolve safety issues in which operators are directly or indirectly exposed to chemicals or fumes in assembling dispense heads on chemical drums. However, the chemical drum assembling process involves complex and difficult tasks, such as mating male/female keycodes and fastening screws with large-diameter, which may be very difficult to be performed by a single-arm robot with a commercial rigid F/T sensor. In order to solve the problems, a method for assembling a chemical drum using dual-arm collaborative robot system, compliance F/T sensor, robot vision and gripper is presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.2903-2923
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• 2023

Knowledge recommendation is a type of recommendation system that recommends knowledge content to users in order to satisfy their needs. Although using graph neural networks to extract data features is an effective method for solving the recommendation problem, there is information loss when modeling real-world problems because an edge in a graph structure can only be associated with two nodes. Because one super-edge in the hypergraph structure can be connected with several nodes and the effectiveness of knowledge graph for knowledge expression, a dual-channel hypergraph convolutional neural network model (DCHC) based on hypergraph structure and knowledge graph is proposed. The model divides user data and knowledge data into user subhypergraph and knowledge subhypergraph, respectively, and extracts user data features by dual-channel hypergraph convolution and knowledge data features by combining with knowledge graph technology, and finally generates recommendation results based on the obtained user embedding and knowledge embedding. The performance of DCHC model is higher than the comparative model under AUC and F1 evaluation indicators, comparative experiments with the baseline also demonstrate the validity of DCHC model.

• 한국ITS학회 논문지
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• 제9권6호
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• pp.105-112
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• 2010

최근, 무선통신 시스템의 발전으로 다중대역을 위해 광대역에서 동작하는 회로들이 소개되었다. 하지만 광대역에서 동작하는 회로들은 필연적으로 크기가 증가하는 단점이 있다. 이중대역에서 동작하는 회로는 원하는 두 주파수에서만 동작하기 때문에 불필요한 소자들의 감소로 소형화가 가능하다. Wilkinson 전력 분배기는 무선통신시스템에서 전력분배를 위해 일반적으로 사용되는 소자로써, 이 또한 최근 이중대역이 요구되어지고 있다. 본 논문에서는 IEEE 802.11n WLAN을 위하여 2.45GHz와 5.2GHz에서 동작하는 소형화된 이중대역 Wilkinson 전력 분배기를 제안한다. 제안된 Wilkinson 전력 분배기는 일반적인 Wilkinson 전력분배기의 ${\lambda}$/4파장 부분을 ${\pi}$-형 병렬 스터브라인으로, 전기적 길이와 임피던스를 변환하여 수행되었다.

• Tribology and Lubricants
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• 제32권3호
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• pp.82-87
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• 2016

We performed an experimental research on lubricant oil in dual fuel medium-speed engines. It is important to select the appropriate lubricant oil because it could significantly affect engine lifetime and performance. We generally recommend the selection of the lubricant oil according to the fuel grades as contents in the project guide. However, it is a considerable challenge for shipyards to implement this concept because of the lack of space to install the complicated lubricating oil system for dual fuel engines. Therefore, we determine the adaptability of one-common lubricant oil for HiMSEN dual fuel engine through this experimental research. To check abnormality in gas mode operation and durability of engine components when a lubricating oil with high BN (base number) is used, overhaul inspections and lubricant oil analysis are carried out two times, and four times, respectively, during an operation of approximately 300 h. We investigated the variations in kinematic viscosity, base number, element quantity, pentane insoluble and sulfated ash in lubricant oil analysis. Moreover, we also investigated whether the deposit formation or wear occurred in various bearings, injectors, exhaust valves, intake valves, piston rings and so on through the overhaul inspections. There are no problems in the lubricant analysis and the overhaul inspections. Through the experimental research, we confirm that one-common lubricant oil should be selected according to the higher sulfur content of fuel oil in dual fuel engines.

• 대한수학회지
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• 제41권5호
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• pp.821-864
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• 2004

Both parametric and parameter-free necessary and sufficient optimality conditions are established for a class of nondiffer-entiable nonconvex optimal control problems with generalized fractional objective functions, linear dynamics, and nonlinear inequality constraints on both the state and control variables. Based on these optimality results, ten Wolfe-type parametric and parameter-free duality models are formulated and weak, strong, and strict converse duality theorems are proved. These duality results contain, as special cases, similar results for minmax fractional optimal control problems involving square roots of positive semi definite quadratic forms, and for optimal control problems with fractional, discrete max, and conventional objective functions, which are particular cases of the main problem considered in this paper. The duality models presented here contain various extensions of a number of existing duality formulations for convex control problems, and subsume continuous-time generalizations of a great variety of similar dual problems investigated previously in the area of finite-dimensional nonlinear programming.

• 실천공학교육논문지
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• 제5권2호
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• pp.139-149
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• 2013

본 논문에서는 한국기술교육대학교가 새롭게 제시하는 한국형 듀얼 시스템인 K-Dual 시스템의 개념과 세부모델들에 대해 제안하고 주요사항에 대해 논의한다. K-Dual 시스템은 기존의 우리나라에서 다양한 형태로 진행되어 오고 있는 일학습 병행관련 제도들의 문제점을 보완하고 이들을 하나의 시스템으로 통합 운영하기위해 한국의 실정에 맞게 대한민국 교육시스템에 적합하게 설계한 한국형 일학습 병행 모델로 크게 Academic 트랙과 Vocational 트랙의 2가지 트랙에 IPP, $W^3$ 및 기업대학형의 3가지 유형으로 정의된다. Academic 트랙의 경우에는 선진학 후취업 모델로 대학에 진학중인 학생들을 대상으로 현장실습교육을 강화함으로써 향후 취업 시 현장 적응력을 극대화시키고 취업과 연계하여 취업률 및 취업의 질/업무 만족도를 향상하고자 함에 그 목적이 있다. 반면 Vocational 트랙의 경우 기업체의 재직자를 대상으로 일정기간의 경력을 취득한 후 연계된 대학 또는 전문대학의 정규교과과정과 함께 일정한 산업체 현장실무/실습 교육(예, 기업체 멘토의 지도하에 진행되는 프로젝트 수행 등) 학점을 이수하면 대졸 또는 전문대졸 학위를 취득하는 형태(선취업 후진학 모형)로 교과과정은 대학과 기업체가 공동으로 설계 및 운영하게 된다. 본 논문에서 제안하는 K-Dual 시스템이 성공적으로 정착되어 운영되기 위해서는 무엇보다도 기업의 대학교육에 대한 적극적인 참여와 열린 마음가짐이 필요하며, 대학은 체계적인 학사시스템 설계 및 온/오프라인 교육센터 등 인프라 구축이 선행되어야 할 뿐만 아니라 정부도 참여기업 및 대학을 위한 제도적 재정적 지원을 아끼지 않아야 할 것이다.

• 상하수도학회지
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• 제18권5호
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• pp.608-618
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• 2004

Since polyelectrolytes have been used as conditioners, conventionally only a single polyelectrolyte has been added for sludge conditioning. However, the amount of polyelectrolyte needed for optimal conditioning of sludge is very critical. Overdosing reduces the sludge dewaterbility. In this experimental study, sludge conditioning with single or dual polyelectrolyte was conducted to avoid problems associated with overdosing. Single polyelectrolyte conditioning was conducted by one of cationic, nonionic, and anionic polyelectrolytes. The dual polyelectrolyte conditioning was performed by adding one polyelectrolyte and another one in sequence. The dewaterbility of sludges were measured by SRF(specific resistance to filtration), TTF(time to filter), CST(capillary suction time) respectively. Additionally, parameters such as turbidity, zeta potential, viscosity of conditioned sludges or supematant were measured to evaluate the changed characteristics of sludge by addition of polyelectrolytes. From the experiment results, it was concluded that single polyelectrolyte conditioning had a high probability of overdosing, whereas dual polyelectrolyte conditioning resulted in a better dewaterbility and less chance of overdosing. But, it was also found that dosing sequence in dual conditioning was very important according to the characteristics of sludge. Parameters such as viscosity, turbidity, zeta potential were found to be useful as a means of evaluating sludge dewaterbility.

• 한국항해항만학회지
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• 제41권2호
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• pp.63-70
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• 2017

Despite the remarkable continual growth of the world cruise industry, studies have yet to be attempted on many revenue management problems in cruise operations. This paper suggests two schemes that can be easily applied to cruise revenue management: optimal dual pricing and passenger safety level. In optimal dual pricing, a pair of higher and lower prices is applied to cabin reservation through market segmentation. This scheme can be executed with a linear price-response function for the current unreserved cabins. A cruise line could benefit from this scheme to maximize reservation revenue while attaining full occupancy. The dual pricing scheme is also devised to produce only integer demands to suit real management practices. The life boat capacity is an additional service capacity unique to the cruise industry, catering to passengers' safety. The concept of passenger safety level is defined and computed for any passenger life boat capacity of a cruise ship. It can be used to evaluate the passenger safety of a cruise ship in operation, as well as to determine the number of life boat seats required for a new cruise ship. Hypothetical examples are used to illustrate the operation of these two schemes.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2935-2944
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• 2009

중소 PCB 제조업체에서는 외부 생산 환경 변화, 복수개의 제약공정, 많은 공정수, 긴 리드타임, 동일공정 반복생산 등의 특징으로 인하여 효과적인 생산 스케쥴 작성에 많은 어려움을 겪고 있다. 최근 TOC 이론에서 제시하고 있는 DBR기법을 PCB 생산라인에 적용하고자 하는 시도는 진행되고 있으나, 제약공정을 1개만 설정하도록 하는 일반적인 DBR로서는 PCB 생산라인의 특성상 충분한 효과를 기대할 수 없는 현실이다. 따라서 본 논문에서는 PCB 생산라인에서 효과적인 생산스케줄링을 수립하기 위하여 TOC의 DBR기법을 발전시킨 복수 DBR기법을 제시하였다. 또, 실제로 국내 중소 PCB 제조업체에 복수 DBR을 적용하여 제조 리드타임을 20%이상 단축함을 확인하였다.