• Journal of the Korean Operations Research and Management Science Society
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• v.42 no.2
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• pp.19-34
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• 2017

In this study, we develop an optimal sourcing strategy considering compensation orders to mitigate the supply chain disruption risks. We considered two-echelon supply chain consisting of a single buyer and multiple suppliers who have fixed transaction cost and probabilistic disruption risks. Under this setting, we provide the joint optimization method to determine the number of suppliers and the order quantities. Through numerical examples, we provide managerial implications on the sourcing strategy by investigating changes in the order quantities and the number of suppliers due to the degree of supply chain disruption risks.

• Electronics and Telecommunications Trends
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• v.35 no.4
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• pp.149-157
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• 2020

Security threats in supply-chains can be targeted at all the users who use products related to these supply-chains as well as at single equipment or individuals. This implies that these security threats can cause nationwide economic and social damages. In particular, it is true that hardware security threat analysis technology in supply-chains has significant technical barriers due to the lack of software knowledge as well as the need to study and understand undisclosed hardware designs. In this paper, we discuss the future direction of studies by introducing basic concepts and attack cases, along with domestic and foreign technology trends related to supply-chain security technology.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1227-1234
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• 2015

The efficient electric power demand management in electric power supply industry is currently being changed by distributed generation. Meanwhile, small-scale distributed generation systems using renewable energy are being constructed worldwide. Several small-scale renewable distributed generation systems, which can supply electricity to the grid at peak load of the grid as per policy such as demand response programs, could help in the stability of the electric power demand management. In this case, the power quality of the small-scale renewable distributed generation system is more significant. Low prices of power semiconductors and multilevel inverters with high power quality have been recently investigated. However, the conventional multilevel inverter topology is unsuitable for the small-scale renewable distributed generation system, because the number of devices of such topology increases with increasing output voltage level. In this paper, a single-phase multilevel inverter based on H-bridge, with DC_Link divided by bi-directional switches, is proposed. The proposed topology has almost half the number of devices of the conventional multilevel inverter topology when these inverters have the same output voltage level. Double Fourier series solution is mainly used when comparing PWM output harmonic components of various inverter topologies. Harmonic components of the proposed multilevel inverter, which have been analyzed by double Fourier series, are compared with those of the conventional multilevel inverter. An inverter prototype is then developed to verify the validity of the theoretical analysis.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.83-97
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• 2012

In this paper, we consider a single-manufacturer single-buyer supply chain problem where a single manufacturer purchases and processes raw materials into a family of items in order to deliver a family of items to a single buyer at a fixed interval of time for effective implementation of Just-In-Time Purchasing. An integrated multi-item lot-splitting model of facilitating multiple shipments in small lots between buyer and manufacturer is developed in a JIT Purchasing environment. Previous research on the integrated model assumed that the manufacturer orders raw materials m (integer) times for every production run (lot multiplier policy for the raw material). In this paper, we consider a generalized policy in the replenishment of raw materials, allowing lot multiplier policy and lot splitting policy. An iterative solution procedure is developed to find the order interval for finished goods and raw materials, and number of shipments between buyer and manufacturer. We show by numerical example that when the integrated policy is adopted by both buyer and manufacturer in a cooperative manner, both parties can benefit.

• Smart Structures and Systems
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• v.28 no.6
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• pp.811-825
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• 2021

High-voltage isolating switches play a paramount role in ensuring the safety of power supply systems. However, their exposure to outdoor environmental conditions may cause serious physical defects, which may result in great risk to power supply systems and society. Image processing-based methods have been used for anomaly detection. However, their accuracy is affected by numerous uncertainties due to manually extracted features, which makes the anomaly detection of isolating switches still challenging. In this paper, a vision-based anomaly detection method for isolating switches, which uses the rotational angle of the switch system for more accurate and direct anomaly detection with the help of deep learning (DL) and image processing methods (Single Shot Multibox Detector (SSD), improved frame differencing method, and Hough transform), is proposed. The SSD is a deep learning method for object classification and localization. In addition, an improved frame differencing method is introduced for better feature extraction and a hough transform method is adopted for rotational angle calculation. A number of experiments are conducted for anomaly detection of single and multiple switches using video frames. The results of the experiments demonstrate that the SSD outperforms the You-Only-Look-Once network. The effectiveness and robustness of the proposed method have been proven under various conditions, such as different illumination and camera locations using 96 videos from the experiments.

• Journal of Power Electronics
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• v.16 no.2
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• pp.464-472
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• 2016

This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a single-phase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.

• The Journal of Information Systems
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• v.19 no.1
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• pp.79-96
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• 2010

The organizations in the competitive business environment are under pressure of handling internal management processes as well as external supply chain issues. In addition, the paradigm of supply chain management (SCM) has been shifted from static to dynamic problems. For the efficient SCM, organizations should be a RTE (Real Time Enterprises) that views entire supply chains as a single entity. In this paper, the agent system that makes RTE and dynamic supply chains possible is developed. Then, the developed agent system is verified in the TAC SCM(Trading Agent Competition Supply Chain Management) experimental environment and a dashboard is also developed for monitoring management activities of supply chains. The contributions of this paper are as followings. First, unlike the previous agent systems, the suggested agent system in this paper provides autonomy and scalability using SOA. Second, this suggested model for dynamic environment can be applied for the development of software supporting a SCM.

• Journal of The Korea Institute of Healthcare Architecture
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• v.29 no.4
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• pp.57-67
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• 2023

Purpose: Recently, the operating unit remodeling compititon has been increasing rapidly in Korea, but there are no design infomation for spatial planning of sterile supply storage. Therefore, the propose of this study is to present area composition of the operating unit after remodeling. Methods: For literature review, the 6 studies and guidelines of operating unit(guidelines in the U.S, Australia, UK and Korea and 2 studies in Korea) conducted surveys and analysis. Room and space composition and zone of operating unit are redefined for this study. For obtaining area, to conduct masuring and calcuating of document of operating unit before and after remodeling in 3 cases. There are some patterns of plan in operaing unit by sterile supply storage. This study derived data for attributes of area composition of sterile supply storage. Results: The results of this study are as follows: First, Reviewing previous studies and Guidelines, for this study the suggested model was 5 zones(Operating zone, Support zone, Patient zone, Staff zone, Circulation zone) and redefined each room and space. Second, For infection control, sterile supply storage was provided to directly accessible to the operating room. Third, According to ralation of operting room and sterile supply storage, there are two types : 'double loaded type' and 'single loded type'. Sterile supply storage shall increase area of ciculation zone. Implications: This study can be used as primary data on remodeling of operating unit. In addition, it suggests that for infect control sterile supply storage is functional area.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.2
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• pp.116-127
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• 1989

Research on reheating cooling cycle and its practical application have been made to prevent unequalized distribution of temperature and humidity of room due to lack of supply air volume and dewdrops on supply diffusers to be taken place as a result of lower temperature of supply air than that of dew point of room air in cooling cycle of constant air volume, single duct, single zone and draw-through fan type. In view of the fact that human body is insensitive to humidity, it is possible not only to construct the complete non-reheating cooling cycle by increasing the humidity point allowable with the deduction of occupant's sense of pleasantness minimizing, but also to get cooling cycle decreasing the reheating quantity if the humidity exceeds the point allowable. In addition, it is possible to save maximum 8% in electric energy for cooling in cooling system by constructing non-reheating cooling cycle instead of reheating cooling cycle and by increasing the relative humidity of room from 50% to 65% in case efficiency and air pressure of cooling system are low. It is also possible to get an optimum cooling cycle by determining the room humidity in consideration of pleasantness of occupants and conservation rate of electric energy if the cooling capacity, efficiency and total pressure of cooling equipment are fixed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.685-688
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• 2006

A single-phase uninterruptible power supply system suitable for a SMES unit is proposed to achieve a simple circuit configuration and higher system reliability. It reduces the number of switching devices by applying a common-arm scheme. Operational principles to normal, stored-energy, and bypass mode are discussed in detail. Eliminating some of the switches or substituting passive components for active switches generally increases the sophistication and reduces degree of freedom in control strategy. However, the high-performance digital controller ran execute the complicated control task with no additional cost. The validity of the proposed UPS system will be verified by a computer-aided simulation.