• Structural Engineering and Mechanics
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• 제65권3호
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• pp.349-357
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• 2018

An extensive research was undertaken to study the vibration serviceability of a long-span and light-weight floor subjected to human loading experimentally and numerically. Specifically, heel-drop test was first conducted to capture the floor's natural frequencies and damping ratios, followed by jumping and running tests to obtain the acceleration responses. In addition, numerical simulations considering walking excitation were performed to further evaluate the vibration performance of a multi-panel floor under different loading cases and walking rates. The floor is found to have a high frequency (11.67 Hz) and a low damping ratio (2.32%). The comparison of the test results with the published data from the 1997 AISC Design Guide 11 indicates that the floor exhibits satisfactory vibration perceptibility overall. The study results show that the peak acceleration is affected by the walking path, walking rate, and adjacent structure. A simpler loading case may be considered in design in place of a more complex one.

• 대한전기학회논문지:전력기술부문A
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• 제55권12호
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• pp.561-569
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• 2006

Because of the trend of deregulation, power industry is going through an unprecedented transformation in North America and Europe, and there are a host of acquisitions and mergers by the private sector to position themselves to take advantage of new business opportunities. Deregulation has accelerated the development of smaller generators and fuel cells will gradually become more attractive to mainstream electricity users as they improve in capability and decrease in cost. Fuel Cell technology is surveyed and the potential of using fuel cell as a distributed generation source is presented. This paper recommends the fuel cell power plants as alternative energy sources for distributed generation in Jeju Island, Korea. This will help in increasing fuel efficiency, at least double the current thermal plants', increasing the reliability of power supply, reducing the dependency on the HVDC link, providing quality power to the growing infrastructure, and maintaining clean air in meeting the free-trade international island.

• Environmental Engineering Research
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• 제17권2호
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• pp.111-116
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• 2012

This study investigates the complete removal of nitrate and the recovery of valuable ammonium salt by the combination of nanoscale zero-valent iron (NZVI) and a membrane contactor system. The NZVI used for the experiments was prepared by chemical reduction without a stabilizing agent. The main end-product of nitrate reduction by NZVI was ammonia, and the solution pH was stably maintained around 10.5. Effective removal of ammonia was possible with the polytetrafluoroethylene membrane contactor system in all tested conditions. Among the various operation parameters including influent pH, concentration, temperature, and contact time, contact time and solution pH showed significant effects on the ammonia removal mechanism. Also, the osmotic distillation phenomena that deteriorate the mass transfer efficiency could be minimized by pre-heating the influent wastewater. The ammonia removal rate could be maximized by optimizing operation conditions and changing the membrane configuration. The combination of NZVI and the membrane contactor system could be a solution for nitrate removal and the recovery of valuable products.

• 융합신호처리학회논문지
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• 제10권4호
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• pp.289-293
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• 2009

This study proposes a novel double-base log encoder (DBLE) for flash Analog-to-Digital converters (ADCs). Analog inputs of flash ADCs are represented in logarithmic number systems with bases of 2 and 3 at the outputs of DBLE. A look up table stores the sets of exponents of base 2 and 3 values. This algorithm improves the performance of a DSP (Digital Signal Processor) system that takes outputs of a flash ADC, since the double-base log number representation does multiplication operation easily within negligible error range in ADC. We have designed and implemented 6 bits DBLE implemented with ROM (Read-Only Memory) architecture in a $0.18\;{\mu}m$ CMOS technology. The power consumption and speed of DBLE are better than the FAT tree and binary ROM encoders at the cost of more chip area. The DBLE can be implemented into SoC architecture with DSP to improve the processing speed.

• 공학교육연구
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• 제10권1호
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• pp.5-19
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• 2007

공과대학은 다른 인문, 사회 계열과는 달리 교양교육과정이 전공과정과 뚜렷하게 구분되기 때문에 어떤 형태와 내용으로 구성되어 있느냐에 따라 학생의 학습 성과(outcomes)에 많은 영향을 미칠 수 있다. 또한 한국의 공과대학에서는 공학교육인증(ABEEK) 시행에 따라 그 기준에 부합하는 교양교육과정을 구성하는 방법상의 문제에 많은 혼란이 있어 왔다. 따라서 본 연구에서는 미국의 우수한 공과대학으로 꼽히고 있는 스탠포드대학교(Stanford University), 메사추세스공과대학(Massachusetts Institute of Technology), 로즈헐맨공과대학(Rose-hulman Institute of technology)과 프린스턴대학교(Princeton University)와 미시간대학교(Michigan University-Ann Arbor) 그리고 펜실베이니아 주립대학교(Pennsylvania State University)와 캔자스주립대학교(kansas state University)의 교양교육과정을 비교하여 한국 공과대학 교양교육과정 구성에 시사점을 찾기 위해 구현방식과 학문적 영역상의 특성을 분석하여 제시하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1901-1904
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• 2003

MPC or model predictive control is representative of control methods which are able to handle physical constraints. Closed-loop stability can therefore be ensured only locally in the presence of constraints of this type. However, if the system is neutrally stable, and if the constraints are imposed only on the input, global aymptotic stability can be obtained; until recently, use of infinite horizons was thought to be inevitable in this case. A globally stabilizing finite-horizon MPC has lately been suggested for neutrally stable continuous-time systems using a non-quadratic terminal cost which consists of cubic as well as quadratic functions of the state. The idea originates from the so-called small gain control, where the global stability is proven using a non-quadratic Lyapunov function. The newly developed finite-horizon MPC employs the same form of Lyapunov function as the terminal cost, thereby leading to global asymptotic stability. A discrete-time version of this finite-horizon MPC is presented here. The proposed MPC algorithm is also coded using an SQP (Sequential Quadratic Programming) algorithm, and simulation results are given to show the effectiveness of the method.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.709-717
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• 2017

Mucosal tissues are the initial site through which most pathogens invade. As such, vaccines and adjuvants that modulate mucosal immune functions have emerged as important agents for disease prevention. Herein, we investigated the immunomodulatory mechanisms of the B subunit of Escherichia coli heat-labile enterotoxin type IIa ($LT-IIa-B_5$), a potent non-toxic mucosal adjuvant. Alternations in gene expression in response to $LT-IIa-B_5$ were identified using a genome-wide transcriptional microarray that focused on dendritic cells (DC), a type of cell that broadly orchestrates adaptive and innate immune responses. We found that $LT-IIa-B_5$ enhanced the homing capacity of DC into the lymph nodes and selectively regulated transcription of pro-inflammatory cytokines, chemokines, and cytokine receptors. These data are consistent with a model in which directional activation and differentiation of immune cells by $LT-IIa-B_5$ serve as a critical mechanism whereby this potent adjuvant amplifies mucosal immunity to co-administered antigens.

• 대한안전경영과학회지
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• 제17권1호
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• pp.193-201
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• 2015

The history of Korea Qualification system began after the Korea War. The Qualification was recognized to it's value with economic growth until the 2000. But the value of qualifications has to be re-evaluated under the current global environments. Almost Previous research has not to work for the value of qualifications all of Korea. So, This study presents a evaluation structure frame to work and some evaluation factors for the qualification value. In addition, the methodology proposed to obtain results using the AHP weights based on the evaluation methodology and questionnaire. The analysis results are used as a basis for selecting the future policy direction of the national qualification.

• 한국해양공학회지
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• 제24권4호
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• pp.86-93
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• 2010

RFID has been used as an identification tool that substitutes for bar codes. Its areas of application are increasing due to its suitability in ubiquitous environment. In this paper, first, we review various aspects of RFID, including standards, characteristics, and relationships with wireless sensor networks. Then, we review the technical aspects of RFID and its areas of application, e.g., supply chain management (SCM) and manufacturing since 2005. SCM, in which RFIDs can shorten lead time and ensure the quality of products, is one of the most active application areas. Manufacturing is a relatively new area for RFID applications, but it is believed that it can enhance the productivity and the reliability of the products. Also, the authors suggest research issues and limitations of RFID, as well as possible application areas related to marine engineering.

• 한국지역사회생활과학회지
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• 제27권1호
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• pp.83-93
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• 2016

The purpose of this study was to examine the status of coffee intake in South Korea by analyzing the 4th Korea National Health and Nutrition Examination Survey. The results showed that 52.3% of Koreans consumed coffee at least once a day. Males consumed coffee more frequently than females and those aged 20-39 years and 40-59 years consumed coffee most frequently. Coffee drinkers consumed coffee two times a day and 138 mL each time on average. Coffee was mainly consumed either at home (44.8%) or in the workplace (36.1%); males drank coffee most frequently in the workplace and females did so at home. Milk coffee including coffee from vending machines and coffee mix (73.8%) was the most common type of coffee consumed. The results of this study would extend the understanding of the general status of coffee intake in South Korea, which has shown steady growth but remains a relatively overlooked research area.