• Journal of Power Electronics
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• 제12권6호
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• pp.878-885
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• 2012

A new sustainer with primary-side integration of DC/DC converters and energy recovery(SPIDER) circuits is proposed. The proposed circuit operates as a DC-DC converter during address period and energy recovery circuit during sustain period. Therefore, the conventional three electronic circuits composed of the power supply, X-driver, and Y-driver can be reduced to one circuit. As a result, it has desirable advantages such as a simple structure, less mass, fewer devices and cost reduction. Moreover, since the Zero Voltage Switching (ZVS) of all power switches can be guaranteed, a switching loss can be considerably decreased. To confirm the operation, validity, and features of the proposed circuit, experimental results from a prototype for 42-inch PDP are presented.

• 대한족부족관절학회지
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• 제16권2호
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• pp.94-100
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• 2012

Purpose: The purpose of this study is to analyze the clinical features of distal tibia fractures and to evaluate the treatment outcomes of minimally invasive plate osteosynthesis (MIPO). Materials and Methods: From January 2004 to December 2009, 84 cases of 81 patients treated with plate fixation for distal tibia fracture were enrolled in this retrospective review. We investigated age, sex, injury mechanism, fracture patterns, and complications, and the clinical features were analyzed. To evaluate the treatment outcomes of MIPO, we divided into two groups. MIPO group consisted of 55 patients were treated with MIPO technique and conventional group consisted of 18 patients were treated with open reduction and internal fixation with conventional anterolateral plating. The results were compared between two groups by assessing bony union time, operation time, amount of blood loss, range of ankle motion, clinical score by American Orthopaedic Foot and Ankle Society (AOFAS) score, and post-operative complications. Results: The mean age of 81 patients with distal tibia fracture was 54.8 years. According to AO classification, A1:2:3 were 16, 20, 16 patients, B1:2:3 were 2, 8, 7, C1:2:3 were 1, 3, 11 patients. According to injury mechanism, slip down injury was patients, traffic accident was 26, fall from height injury was 14 patients respectively. The type A fractures were lower energy trauma and more older patients. The type C fractures were higher energy trauma and younger patients. MIPO group was better than conventional group in operative time, blood loss, bony union time, and ankle joint motion. In complications, MIPO group showed no nonunion and infection, one malunion, one skin necrosis, nine skin irritations, and one screw breakage. Conventional group showed two nonunion, four infections, two skin necrosis, and one metal failure. Conclusion: Distal tibial fractures caused by low energy trauma were on the increase. Minimal invasive plate osteosynthesis was shorter bony union time and operation time, less blood loss, and larger ankle motions than conventional open reduction and plate fixation.

• 풍력에너지저널
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• 제13권3호
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• pp.43-52
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• 2022

Although wind turbines have obtained type certification according to international standards and are released to the market, they cannot be regarded as design evaluations that consider site characteristics. Therefore, it is necessary to study the site-specific load analysis method based on the meteorological data measured at the candidate site. In this study, site-specific load calculation was performed based on the meteorological data from the Jeju Haengwon mast. Analysis results were compared and analyzed with the results calculated by IEC design Class (IIA). For the fatigue loads at the blade root and tower base, the site-specific condition was lower than the IEC IIA, but in the case of the ultimate load, the site-specific condition showed higher results in some design load cases (DLCs). Selecting a wind turbine suitable for a site through load evaluation considering site conditions can prevent the reduction of operation and maintenance (O&M) costs and the power loss caused by downtime. Finally, it is expected to contribute to the project's levelized cost of energy (LCOE) reduction.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.205-210
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• 2009

Generally, the building's windows and ventilation for the purpose of mining and the vista and windows by emotional engineering design area is a growing trend. According to the flow of energy is lost from the building, will be achieved through the walls and roof and windows. Among these, the window through the loss of about 45% of the entire building is big enough to rate. In addition, the building regulation U-value Limitation of window is $3.3W/m^2$ K in southern regions, while U-value Limitation of wall is $0.35{\sim}0.58W/m^2$ K. It means that the energy loss through windows is six times more than it through wall. Therefore, the purpose of this study is to evaluate the environmental performance of the super window system by verification experiment. The results of this study are as follows; 1)Thermal performance of insulated Super Window measured as $1.44W/m^2$ $^{\circ}C$ 2)Required energy for heating was cut down about 5.3% from 266.99 $MJ/m^2$ yr to 252.85 $MJ/m^2$ yr 3)Super Window's reduction rates increased 4.1% from 31.48% to 35.58% when it is compared to normal windows. 4)Building energy efficiency rating elevated from 2nd rating to 1st rating.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.58-63
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• 2012

As the exterior of building has been considered one of th important parts, the use of glass that is suitable to express various appearances gets raised. However, windows have 6~7times lower insulating performance than insulated walls. Lately, highly efficient windows are required as the needs for reduction of energy consumption come to the force. Therefore, Nowadays more people use cooling systems in summer, more the use of Low-E glazing is increasing. Because it is good to block Solar Radiant Energy which can cause much of heat loss while cooling system is working. This study measures U-value of the double Low-E glazing window and commonly used single Low-E glazing window. And then the effect of each window on the efficiency rating has been analyzed applying to the certification system of the building energy efficiency rating which has implemented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권7호
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• pp.3064-3094
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• 2018

Currently, the Underwater Sensor Networks (UWSNs) is mainly an interesting area due to its ability to provide a technology to gather many valuable data from underwater environment such as tsunami monitoring sensor, military tactical application, environmental monitoring and many more. However, UWSNs is suffering from limited energy, high packet loss and the use of acoustic communication. In UWSNs most of the energy consumption is used during the forwarding of packet data from the source to the destination. Therefore, many researchers are eager to design energy efficient routing protocol to minimize energy consumption in UWSNs. As the opportunistic routing (OR) is the most promising method to be used in UWSNs, this paper focuses on the existing proposed energy efficient OR protocol in UWSNs. This paper reviews the existing proposed energy efficient OR protocol, classifying them into 3 categories namely sender-side-based, receiver-side-based and hybrid. Furthermore each of the protocols is reviewed in detail, and its advantages and disadvantages are discussed. Finally, we discuss potential future work research directions in UWSNs, especially for energy efficient OR protocol design.

• 한국지열·수열에너지학회논문집
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• 제19권2호
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• pp.1-7
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• 2023

In this study, in order to reduce the amount of infiltration generated from windows among the heat loss generated in the building, energy shutters were installed on the windows to conduct experiments on the change in internal temperature and amount of infiltration due to the pressure difference between the environmental chamber and the pressure box. As a result of the experiment, when the pressure difference was 0Pa, the initial temperature of the pressure box of window was higher than that of the pressure box of the energy shutter, but when the pressure difference occurred, the internal temperature of the pressure box of the energy shutter was higher. In addition, the amount of infiltration of the energy shutter was lower than that of the windows in all experimental conditions, and it was concluded that the reduction rate of the infiltration load (of the energy shutters) could be reduced by 53.3% compared to that of the windows.

• KIEAE Journal
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• 제17권2호
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• pp.29-34
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• 2017

Purpose: Recently, significant heat loss through the window takes place in buildings. Nevertheless, there exists little literature concerning the exterior horizontal shading devices and the design criteria are not clearly settled yet. Applying the exterior horizontal shading devices is more efficient as compared to the interior shading devices in that solar radiation can be directly blocked before passing through the window or the envelope. The purpose of this study is to reduce the internal load by designing the exterior horizontal shading devices and verify the degree of reduction in energy consumption. Method: This study aims to reduce energy consumption in cooling and heating through proposing proper length and shape of the exterior horizontal shading devices in public buildings. In the process, actual energy data and the Design Builder simulation program are utilized. In addition, economic aspect is considered to figure out the optimal length of the exterior horizontal shading devices that maximizes efficiency. Result: As a result, the proper length and shape of the exterior horizontal shading devices are provided as follows: 1) Energy consumption in cooling and heating is minimized when the exterior horizontal shading devices are designed as 0.5m*2. 2) Electricity bill is the lowest when the exterior horizontal shading devices are designed as 3.3m*2. The gap between maximum and minimum electricity bill is about 7.8~14%.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2042-2048
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• 2014

In medium voltage electrical distribution networks, reforming the loss reduction is important, and in line with this, the issue of system engineering and use of proper equipment Expansion of distribution systems results in higher system losses and poor voltage regulation. Therefore, an efficient and effective distribution system has become more important. So, proper selection of conductors in the distribution system is crucial as it determines the current density and the resistance of the line. Evaluation of aging conductors for losses and costs imposed in addition to the careful planning of technical and economic networks can be identified in the network design. In this paper the use of imperialist competitive algorithm; genetic algorithm; is proposed to optimal branch conductor selection and reconstruction in radial distribution systems planning. The objective is to minimize the overall cost of annual energy losses and depreciation on the cost of conductors to improve productivity given the maximum current carrying capacity and acceptable voltage levels. Simulations are carried out on 69-bus radial distribution network using genetic algorithm approaches to show the accuracy as well as the efficiency of the proposed solution technique.

• ETRI Journal
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• 제38권1호
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• pp.133-140
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• 2016

This paper presents a method of parasitic inductance reduction for high-speed switching and high-efficiency operation of a cascode structure with a low-voltage enhancement-mode silicon (Si) metal-oxide-semiconductor field-effect transistor (MOSFET) and a high-voltage depletion-mode gallium nitride (GaN) fielde-ffect transistor (FET). The method is proposed to add a bonding wire interconnected between the source electrode of the Si MOSFET and the gate electrode of the GaN FET in a conventional cascode structure package to reduce the most critical inductance, which provides the major switching loss for a high switching speed and high efficiency. From the measured results of the proposed and conventional GaN cascode FETs, the rising and falling times of the proposed GaN cascode FET were up to 3.4% and 8.0% faster than those of the conventional GaN cascode FET, respectively, under measurement conditions of 30 V and 5 A. During the rising and falling times, the energy losses of the proposed GaN cascode FET were up to 0.3% and 6.7% lower than those of the conventional GaN cascode FET, respectively.