• Architectural research
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• 제14권3호
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• pp.99-108
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• 2012

An innovative multi-story Semi-Active Tuned Mass Damper (SATMD) building system is proposed to control seismic response of existing structures. The application of adding new stories as large tuned mass and semi-active (SA) resettable actuators as central features of the control scheme is derived. For the effective control of the structures, the optimal tuning parameters are considered for the large mass ratio, for which a previously proposed equation is used and the practical optimal stiffness is allocated to the actuator stiffness and rubber bearing stiffness. A two-degree-of freedom (2-DOF) model is adopted to verify the principal efficiency of the suggested structural control concept. The simulations for this study utilizes the three ground motions, from SAC project, having probability of exceedance of 50% in 50 years, 10% in 50 years, and 2% in 50 years for the Los Angeles region. 12-story moment resisting frames, which are modified as '12+2' and '12+4' story structures, are investigated to assess the viability and effectiveness of the system that aims to reduce the response of the buildings to earthquakes. The control ability of the SATMD scheme is compared to that of an uncontrolled and an ideal Passive Tuned Mass Damper (PTMD) building system. From the performance results of suggested '12+2' and '12+4' story retrofitting case studies, SATMD systems shows significant promise for application of structural control where extra stories might be added.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.946-951
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• 2009

The research aims to study a new, optimum and renewable energy application method that can cover the minimum energy and operation costs within a range of school budgets. By deriving the optimum application method, it is expected to maximize the cooling/heating and water heating energy saving efficiencies for educational facilities. Therefore, this research carried out a study on the new/renewable energy utilization technique diffusion expansion method and the optimum method. As a result, the first optimum plan was introduced with the multi-type geothermal heat pump 174kW + solar heat collector $94\;m^2$ + highly efficient electronic cooling/heating device (EHP) 249.4kW. On the other hand, the second optimum plan was induced as the multi-type geothermal heat pump 255.2kW + highly efficient electronic cooling/heating device (EHP) 168.2kW.

• 설비공학논문집
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• 제21권10호
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• pp.564-574
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• 2009

The study is conducted to study a new, optimum and new and renewable energy application method that can cover the minimum energy and operation costs within a range of school budgets. By deriving the optimum application method, it is expected to maximize the cooling/heating and hot water supply energy saving efficiencies for educational facilities. Therefore, this research implemented a study on the new and renewable energy utilization technique diffusion expansion method and the optimum method. As a result, the first optimum plan was introduced with the multi-type geothermal heat pump 475.6 kW+highly efficient electronic cooling/heating device(EHP) 545.2 kW. On the other hand, the second optimum plan was induced as the multi-type geothermal heat pump 261kW+solar heat collector $240\;m^2$+highly efficient electronic cooling/heating device(EHP) 759.8 kW.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.117-123
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• 2011

The low electric power and high efficiency chips are required because of the appearance of smart phones. Also, high-capacity memory chips are needed. e-MMC(embedded Multi-Media Card) for this is defined by JEDEC(Joint Electron Device Engineering Council). The e-MMC memory for research and development is a memory mulit-chip module of 64GB using 16-multilayers of 4GB NAND-flash memory. And it has simplified the chip by using SIP technique. But mulit-chip module generates high heat by higher integration. According to the result of study, whenever semiconductor chip is about 10 $^{\circ}C$ higher than the design temperature it makes the life of the chip shorten more than 50%. Therefore, it is required that we solve the problem of heating value and make the efficiency of e-MMC improved. In this study, geometry of 16-multilayered structure is compared the temperature distribution of four different geometries along the numerical analysis. As a result, it is con finned that a multilayer structure of stair type is more efficient than a multilayer structure of vertical type because a multi-layer structure of stair type is about 9 $^{\circ}C$ lower than a multilayer structure of vertical type.

• 센서학회지
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• 제16권5호
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• pp.377-383
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• 2007

We describe the fabrication and characterization of a doubly clamped multi-walled carbon nanotube (MWNT). The device was assembled by an application of electric field in solution. The MWNT was clamped on end of metal trench electrodes in solution and deposited with additional platinum (Pt) on edge of electrode for firmly suspending the MWNT by focused ion beam (FIB). The MWNTs range of diameter and length were 100 to 150 nm and 1.5 to $2{\mu}m$, respectively. Electrical characteristics of fabricated devices were measured by I-V curve and impedance analysis. The mechanical deformation was observed by resistivity in high air pressure. Resonant frequency around 6.8 MHz was detected and resistivity was linearly varied according to the magnitude of air pressure. This device could have potential applications in nanoelectronics and various sensors.

• 설비공학논문집
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• 제18권12호
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• pp.984-991
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• 2006

The applications of multi air-conditioners into multiplex and high-rise buildings have been increased by replacing central air-conditioning systems. The pipe length and altitude difference between the indoor and outdoor units can be increased based on installation conditions, which may increase the possibility of flash gas generation at the expansion device inlet. The flash gas generation causes rapid reduction of refrigerant flow rate passing through the expansion device, yielding lower system efficiency. Accumulator heat exchangers have been widely used in multi air-conditioners in order to minimize flash gas generation and obtain system reliability. However, the studies on the heat transfer characteristics and pressure drops of accumulator heat exchangers are very limited in open literature. In this study, the heat transfer rates and pressure drops of accumulator heat exchangers were measured with refrigerant flow rate and operating conditions by using R-22. The heat transfer rate increased with the increase of refrigerant flow rate, while subcooling decreased. The heat transfer rate enhanced with the reduction of inlet superheat and subcooling due to the increased temperature difference between the accumulator and inner heat exchanger.

• 전기학회논문지
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• 제65권8호
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• pp.1369-1375
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• 2016

A rapid progress of the next-generation non-volatile memory device has been made in recent years. Metal/insulator/Metal multi-layer structure resistive RAM(ReRAM) has attracted a great deal of attention because it has advantages of simple fabrication, low cost, low power consumption, and low operating voltage. This paper describes the working principle of the ReRAM device, a review of fabrication techniques, and characteristics of flexible ReRAM devices using graphene oxide as an insulating layer and ReRAM devices using multi-layered insulator. The switching characteristics of the above ReRAM devices have been compared. The oxidized graphene could be employed as an insulator of next generation ReRAM devices.

• Nuclear Engineering and Technology
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• 제39권4호
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• pp.299-312
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• 2007

The program on thermal-hydraulic evaluation by testing and analysis (THETA) for the development and licensing of the new design features in the APR1400 (Advanced Power Reactor-1400) is briefly introduced with a presentation on the research motivation and typical results of the separate effect tests and analyses of the major design features. The first part deals with multi-dimensional phenomena related to the safety analysis of the APR1400. One research area is related to the multidimensional behavior of the safety injection (SI) water in a reactor pressure vessel downcomer that uses a direct vessel injection type of SI system. The other area is associated with the condensation of steam jets and the resultant thermal mixing in a water pool; these phenomena are relevant to the depressurization of a reactor coolant system (RCS). The second part describes our efforts to develop new components for safety enhancements, such as a fluidic device as a passive SI flow controller and a sparger to depressurize the RCS. This work contributes to an understanding of the new thermal-hydraulic phenomena that are relevant to advanced reactor system designs; it also improves the prediction capabilities of analysis tools for multi-dimensional flow behavior, especially in complicated geometries.

• 한국전자통신학회논문지
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• 제16권6호
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• pp.1053-1058
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• 2021

본 논문은 능동소자에 인가되는 게이트 바이어스 전압을 가변하여 X-, K- 및 Ka-대역 신호를 선택적으로 변환할 수 있는 다중대역 혼합기를 제안하였다. 제안한 다중대역 혼합기는 LO 전력 +6 dBm으로 구동하였고 X-대역의 경우, 게이트 바이어스 전압 -0.8 V에서 변환손실 -10 dB 특성, K-대역에서 게이트 바이어스 전압 -0.3 V에서 변환손실 -9 dB 특성, Ka-대역에서는 게이트 바이어스 전압 -0.2 V에서 변환손실 -7.0 dB 특성을 나타내었다. 모든 대역에서 1-dB 압축점 (P1dB)은 +0.5 dBm 특성을 나타내었다.

• 한국전자통신학회논문지
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• 제18권1호
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• pp.1-10
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• 2023

본 논문에서는 기존 유선기반 CCTV 감시시스템과 IP 카메라 시스템에 국산 무선통신기술을 활용한 고화질 영상의 원거리 무선 전송 기술에 대해 설계 및 구현에 대해 성능 평가을 하였다. 무선 다중 IP 카메라 전송 단말장치및 무선통신 RF 모듈간 연동시험과 무선 다중 IP 카메라 기반 영상전송시스템 통합 연동시험으로 영상 전송 시 모듈 연동 적합성을 확인한다.