• Journal of the Korean Ceramic Society
• /
• v.55 no.3
• /
• pp.185-202
• /
• 2018

Photoelectrochemical (PEC) cells can convert solar energy, the largest potential source of renewable energy, into hydrogen fuel which can be stored, transported, and used on demand. In terms of cost competitiveness compared with fossil fuels, however, both photocatalytic efficiency and cost-effectiveness must be achieved simultaneously. Improvement of cost-effective, scalable, versatile, and eco-friendly fabrication methods has emerged as an urgent mission for PEC cells, and solution-based fabrication methods could be capable of meeting these demands. Herein, we review recent challenges for various nanostructured oxide photoelectrodes fabricated by solution-based processes. Hematite, tungsten oxide, bismuth vanadate, titanium oxide, and copper oxides are the main oxides focused on, and various strategies have been attempted with respect to these photocatalyst materials. The effects of nanostructuring, heterojunctions, and co-catalyst loading on the surface are discussed. Our review introduces notable solution-based processes for water splitting photoelectrodes and gives an outlook on eco-friendly and cost-effective approaches to solar fuel generation and innovative artificial photosynthesis technologies.

• Journal of Power Electronics
• /
• v.18 no.4
• /
• pp.1245-1254
• /
• 2018

The stability of a grid-connected system (GCS) has become a critical issue with the increasing utilization of renewable energy sources. Under grid faults, however, a grid-connected inverter cannot work efficiently by using only the traditional droop control. In addition, the unbalance factor of voltage/current at the common coupling point (PCC) may increase significantly. To ensure the stable operation of a GCS under grid faults, the capability to compensate for grid imbalance should be integrated. To solve the aforementioned problem, an improved voltage-type grid-connected control strategy is proposed in this study. A negative sequence conductance compensation loop based on a positive sequence power droop control is added to maintain PCC voltage balance and reduce grid current imbalance, thereby meeting PCC power quality requirements. Moreover, a stable analysis is presented based on the small signal model. Simulation and experimental results verify the aforementioned expectations, and consequently, the effectiveness of the proposed control scheme.

• Journal of Korean Library and Information Science Society
• /
• v.36 no.3
• /
• pp.109-136
• /
• 2005

This paper describes the major components of ISO/IEC 11179 metadata registry (MDR) standard designed to promote data interoperability between systems, explains and discusses semantic web technology and Web ontology languages initiated by W3C that can be employed to further enhance data interoperability, and finally proposes a framework for a new RDF/OWL-based MDR to convert from the current human-readable MDR to machine-readable MDR. If the new MDR is successful, we might be able to offer a better customized information service to users. The future research will be concerned with evaluating objectively the effectiveness of machine-readable MDR in meeting the needs of real users.

• Journal of Preventive Medicine and Public Health
• /
• v.42 no.5
• /
• pp.293-297
• /
• 2009

Objectives : To evaluate the impact of the workplace smoking ban in South Korea, where the male smoking rate is high (57%), on smoking behavior and secondhand smoke exposure. Methods : A workplace smoking ban legislation implemented in April 2003 requires offices, meeting rooms, and lobbies located in larger than 3,000 square meter buildings (or 2,000 square meter multipurpose buildings) should be smoke free. A representative cross-sectional survey, the third wave (2005) of health supplements in the National Health Nutrition Survey of South Korea, was used to measure the impact of the 2003 workplace smoking ban implementation on smoking behavior. It contained 3,122 observations of adults 20 to 65 years old (excluding selfemployed and non-working populations). A multivariate statistical model was used. The self-reported workplace smoking ban policy (full workplace ban, partial workplace ban, and no workplace ban) was used as the key measure. Results : A full workplace smoking ban reduced the current smoking rate by 6.4 percentage points among all workers and also decreased the average daily consumption among smokers by 3.7 cigarettes relative to no smoking ban. Secondhand smoke showed a dramatic decrease of 86 percent (= -1.74/2.03)from the sample mean for full workplace ban. However, public anti-smoking campaign did not show any significant impact on smoking behavior. Conclusions : The full workplace ban policy is effective in South Korea. Male group showed bigger impact of smoking ban policy than female group. The public antismoking campaign did not show any effectiveness.

• Journal of Preventive Medicine and Public Health
• /
• v.17 no.1
• /
• pp.85-93
• /
• 1984

In order to develop some indicies for the evaluation of village health worker's activities and to find out personal characteristics and other factors that affect the activities, an interview survey was conducted to thirty seven village health workers (VHW) in Sunwon, Naega and Bulun townships in Kangwha county, where the Community Health Project of Yonsei University, College of Medicine, has been implemented for the past ten years. In addition, daily activity records of the VHW's were also analyzed. The results are summarized below: First, meeting attendance rates, number of regular family visits, number of antenatal care visits and number of family planning visits were identified as the most meaningful criterion for the evaluation of the village health worker's activities. Second, personal factors that significantly affect the village health worker's activities were identified as age, educational background, living with in-laws, religion, presence of preschool child in the family, holding leader's position of village woman's association concurrently, and duration serving as a VHW. The more aged and the more educated VHWs were the more effective. Those VHWs who were living with in-laws, without preschool child in the family, holding the leader's position of the village woman's association, and the longer service duration were the more effective. Other factors that affect the VHW's activities were the number of households in the target village and the number of natural villages in the target villages. It showed that the smaller the size of number of households and natural villages, the higher the degrees of the effectiveness of the VHW.

• Journal of Korean Physical Therapy Science
• /
• v.27 no.2
• /
• pp.63-79
• /
• 2020

Background: A physical therapy is required to restore motor function of stroke patients, especially gait function improvement is very important to them. Design: Systemic review. Methods: The purpose of this study is to provide objective evidence for the effectiveness of the treadmill training method applied to stroke patients. The literature search for a systematic review was performed on domestic data published from 2010 to 2020 at KISS, RISS, and DBpia. Results: 40 papers meeting the inclusion/exclusion criteria were finally selected. Data analysis was performed according to the research type, intervention method and process, measurement variables, and the risk of bias assessment was conducted as quality evaluation. Conclusion: Various training methods have been suggested and proved that treadmill intervention is an effective method for improving gait and balance. As the goal of rehabilitation for stroke patients is to improve walking and balance, we expect continuous clinical research to continue to establish a more systematic training program and present a new paradigm.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.11
• /
• pp.867-875
• /
• 2020

Quality internal audit (IA) plays a crucial role in accountability, transparency and preserving public properties. This paper gives a brief background of the IA system in Yemen and examines its impact with regards to financial performance in Yemeni commercial banks based on five factors: (i) independence of IAs, (ii) adherence to IA standards, (iii) governance principles implementation, (iv) size of the IA, and (v) frequency of internal audits committees' meetings. The primary data for the study were collected through a questionnaire prepared for this purpose. Fifty questionnaires were distributed out of which forty-two were retrieved and valid in the analysis process. For the empirical analysis, descriptive analysis and T-test were used for verification of the research hypotheses. Results revealed that sticking to standards internal audit, internal auditors' independence and quality governance have significant impact on banks' financial performance, while the size of internal audits committees, as well as their meeting, frequently has insignificant positive impact on banks' performance. Moreover, the country results show that the use of automated internal audit in banks has an impact on improving financial performance. This article provides avenues for further studies, mainly in developing countries, including Yemen, in quality internal audit and financial performance.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.2
• /
• pp.367-372
• /
• 2006

The revision of SOLAS, Chapter V, which entered into force on 1 July 2002, has firmly established the electronic navigational chart as part of the international maritime safety system. Its possible recognition as a paper chart equivalent confirms the considerable safety benefits provided by the official Electronic Chart Display and Information Systems (ECDIS). Elaborated by the Author IAMU Model Course on operational use of ECDIS aims to provide answers to some of the most commonly asked questions regarding various types of electronic charts (ENC, RNC, DNC) and electronic chart systems (ECDIS, RCDS, ECS). Following the earlier adoption of the International Convention STCW 78/95 and IMO model training courses, e.g. IMO Model Course on ECDIS [2], to assist in the implementation of the Convention and the associated IMO Assembly resolutions, a number of IAMU Member Universities had suggested that IAMU should develop model training courses on higher academic level to assist in achieving a more rapid transfer of information and skills regarding new developments in marine technology. The provision of model courses could help instructors improve the quality of their existing courses and enhance their effectiveness in meeting the requirements of the IAMU. In this paper the Author presents the results of two IAMU research projects sponsored by Nippon Foundation, titled 'IAMU Model Course on Training in Operational Use of ECDIS' and 'IAMU Handbook on ECDIS'.

• Environmental Engineering Research
• /
• v.17 no.4
• /
• pp.191-196
• /
• 2012

Analysis of hydrological safety as well as the determination of many substance concentrations are necessary when bioreactor systems are introduced to landfill operations. Therefore, hydrological and substance balance model was developed since it can be applied to various bioreactor landfill operation systems. For the final evaluation of the model's effectiveness, four different methods of injections (leachate alone, leachate and organic waste water, leachate and reverse osmosis concentrate, and all the above three combination) was applied to 1st landfill site of Sudokwon landfill. As a result, the water content of the hypothetical cases for four different systematic bioreactors is projected to be increased up to 35.5% in next 10 years, and this indicated that there will be no problems in meeting the hydrological safety. Also, the final $Cl^-$ concentration after 10-yr time period was projected to be between from minimum 126 to maximum 3,238 mg/L, which could be still a decrease from the original value of 3,278 mg/L. According to the proposed model, whether the substance concentration becomes increased or decreased largely depends on the ratio of initial quantity of inner landfill leachate and the rate of injection.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.7
• /
• pp.1161-1168
• /
• 2016

Battery energy storage system(BESS) attract the attention of the power system operators with its fast response to a disturbance in spite of its limited energy capacity. This paper proposes the operating method of BESS for following the Automatic Generation Control(AGC) frequency control which is centrally distributed by a system operator. As BESS needs to just meet the control requirement from the system operator, it should be able to properly manage the state of charge(SOC) of BESS to be available to control signal. For doing these, the proposed method distributes the control requirement to available batteries in proportion to its SOC. In addition, unavailable batteries are controlled to recover the SOC to an appropriate range, and the recovering power is supplied by available batteries meeting the control requirement. Moreover, the proposed method manages the efficiency of power conversion system (PCS) by limiting the number of PCS to be assigned for the low control requirement. Finally, the case studies are carried out to verify the effectiveness of proposed strategy.