• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.86-95
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• 1993

To investigate perception and attitude toward Group Health Management and Service System for Small and Medium Industries, a survey using self-administered questionnaire was conducted to a part of industries in Inchon, at October 1992. Major dependent variables were perception, attitude, and practice related with Group Health Management and Service System; these variables were measured by 3-point Likert like scale consisted of 7, 5, and 5 items, respectively. Data were collected in 149 industries,72.7% out of 205. Perception nab slightly high, 1.25; attitude was some positive, 1.46; and practice was some passive,0.94. Major determinants of perception, attitude, and practice were sex and age of industry's health manager; perception influenced upon attitude, and perception and attitude had positive effect upon practice. To activate Group Health Management and Service System, it is necessary to develop education and promotion programs for industry's health managers of small and medium industries.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.365-368
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• 2002

본 논문에서는 SANtopiaVM의 데이터 가용성 및 성능을 고려한 에러 핸들링 정책을 제안한다. 제안하는 에러 핸들링 정책은 RAID1과 RAID5에 대한 정책으로 추분하며 에러 발생시의 복구를 위하여 RAID1에서는 FBB(Failed Block Bitmap)라는 비트맵을 추가하여 데이터의 일관성을 유지하고 디스크의 복구 시에는 저기 연산에 대한 부하 분산 및 복구 비용을 감소시키는 쓰기 연산을 제안함으로서 에러 핸들링 시에 입출력 비용을 줄인다. RAID5에서는 추가적인 여분 디스크를 사용한 Sparing Disk 기법을 제안함으로서 디스크 에러 모드에서도 정상 모드의 성능에 근접하는 입출력 성능을 보장하며 빠른 디스크 복구를 지원한다. 제안하는 에러 핸들링 정책은 SANtopiaVM RAID의 오류 발생시, 시스템 성능의 급격한 저하를 완화할 수 있으며 에러로부터 빠른 복구를 지원함으로서 데이터에 대한 효율적인 고 가용성의 특징을 제공한다.

• Membrane and Water Treatment
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• v.6 no.6
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• pp.451-476
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• 2015

Membrane distillation (MD), which can utilize low-grade thermal energy, has been extensively studied for desalination. By incorporating solar thermal energy, the solar membrane distillation desalination system (SMDDS) is a potential technology for resolving the energy and water resource problems. Small-scale SMDDS (s-SMDDS) is an attractive and viable option for the production of fresh water for small communities in remote arid areas. The minimum-cost design and operation of s-SMDDS are determined by a systematic method, which involves a pseudo steady state approach for equipment sizing and the dynamic optimization using overall system mathematical models. The s-SMDDS employing three MD configurations, including the air gap (AGMD), direct contact (DCMD) and vacuum (VMD) types, are optimized. The membrane area of each system is $11.5m^2$. The AGMD system operated for 500 kg/day water production rate gives the lowest unit cost of $5.92/m^3$. The performance ratio and recovery ratio are 0.85 and 4.07%, respectively. For the commercial membrane employed in this study, the increase of membrane mass transfer coefficient up to two times is beneficial for cost reduction and the reduction of membrane heat transfer coefficient only affects the cost of the DCMD system.

• Journal of Ocean Engineering and Technology
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• v.26 no.5
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• pp.11-17
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• 2012

In this study, a damage detection method that uses sensitivity-based finite (FE) element model updating with the natural frequency and zero frequency was proposed. The stiffness matrix for a structure was modified using the sensitivity-based FE model updating method. A sensitivity analysis was used to update the FE model, and the natural frequencies and zero frequencies were considered as target parameters to supplement the information on the vibration characteristics. The locations and values of the damages were estimated from the modified stiffness matrix. Several numerical examples were considered to verify the performance of the proposed method.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.299-306
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• 2010

This paper proposes a new doubly-fed induction generator (DFIG) system using a matrix converter controlled by direct duty ratio pulse-width modulation (DDPWM) scheme. DDPWM is a recently proposed carrier based modulation strategy for matrix converters which employs a triangular carrier and voltage references in a voltage source inverter. By using DDPWM, the matrix converter can directly and effectively generate rotor voltages following the voltage references within the closed control loop. The operation of the proposed DFIG system was verified through computer simulation and experimental works with a hardware simulator of a wind power turbine, which was built using a motor-generator set with vector drive. The simulation and experimental results confirm that a matrix converter with a DDPWM modulation scheme can be effectively applied for a DFIG wind power system.

• Journal of Sensor Science and Technology
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• v.18 no.5
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• pp.385-392
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• 2009

This paper describes the algorithm development of a new body pressure detection sensor for occupant classification system. U.S. Government has required that advanced airbag system should be installed to every automobiles after 2006 according to FMVSS 208 regulation. Therefore, Occupant Classification System should be provided the passenger with safety in order to protect the infants or children that sit in the front passenger seat. When an occupant sits on the chair of the vehicle, deployment of the airbag depends on passenger's weigh distribution and postures. Authors have been developed a new pattern recognition of passenger and weight distribution at the same time by Force Sensing Resistor for the safety.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1501-1510
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• 2014

Low voltage direct current (LVDC) distribution system is a suitable techno-economic candidate which can create an innovative solution for distribution network development with respect to rural electrification. This research focuses on the use of LVDC distribution system to replace some of KEPCO's existing traditional medium voltage alternating current (MVAC) distribution network for rural electrification in South Korea. Considering the technical and economic risks and benefits involved in such project, a comparative techno-economic analysis on the LVDC and the MVAC distribution networks is conducted using economic assessment method such as the net present value (NPV) on a discounted cash flow (DCF) basis as well as the sensitivity analysis technique. Each would play a role in an economic performance indicator and a measure of uncertainty and risk involved in the project. In this work, a simulation model and a computational tool are concurrently developed and employed to aid the techno-economic analysis, evaluation, and estimation of the various systems efficiency and/or performance.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.49-51
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• 2003

가입자망과 메트로 광 가입자망에서 광범위한 적용범위에 대해 광 기술을 선도하는 기존의 WDM은 증가하는 사용자 수를 수용하는 데 어려움을 가지며 WDM은 채널간의 잡음에 의한 제한과 유효 채널의 최대가 WDM 채널에서 광 증폭기 이득의 균일성에 의해 제한받는다. 따라서 사용자 수를 증가시키고 데이터량을 확장시킬 수 있는 CDMA 기술 도입이 하나의 대안으로 요구된다. 본 논문에서는 SMF에서 수십 km 거리를 갖는 가입자망에서 Prime sequence code를 사용한 2.5Gb/s 광 COMA 신호의 색분산 패널티에 대해 연구하였다. 시스템 모델에서, 색분산 패널티, 파형과 디코드된 신호의 아이 다이어그램(eye diagram)이 결과로써 보여지며, prime sequence code 수의 증가에 대해 Chirp 파라미터를 갖는 코드화된 신호의 색분산 패널티를 보인다. 이러한 접근은 pseudo-orthogonality를 가지는 비동기식 광 CDMA의 디자인에 특히 적합할 것이다.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.5
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• pp.751-756
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• 2010

The rapid growth of IT technology has enabled ship automation systems to gain better functionality and safety with reduced costs and crew numbers. Nowadays, the remote maintenance services for the systems are required because a ship may be located in a very remote area. To provide the remote maintenance services, some issues such as how to collect the ship automation systems data, how to monitor a ship's data from onshore offices, how to get support from experts while sailing, and how to reduce the maintenance costs, should be addressed. In this paper, we propose a remote ship maintenance system for remote monitoring and diagnostics of ship automation systems, which is based on both a ship area network to integrate separate system networks and a ship-shore communication infrastructure to support a remote access using satellite communications. Finally, we present the function test to verify the applicability of the proposed system.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.