• Journal of the Korean Data and Information Science Society
• /
• v.22 no.2
• /
• pp.137-148
• /
• 2011

In this paper, we systematically investigate regional differences of the dead due to injuries in cities, towns and counties about transportation accidents, suicides and fall accidents, which have recently been an important issue of health problems in Korea, The data are from the Annual Report on the Cause of Death Statistics in Korea in 2008. They include the deaths over the age 19 from transportation accidents, suicides and fall accidents with the criterion of the International Statistical Classification of Diseases. Poisson HGLM is applied to estimate the mortality rate under the assumption that the number of deaths follow a Poisson distribution, by considering regions as random effects and by adjusting age, sex and standardized residence tax as fixed effects. Using the results of random effects prediction, the regional differences in cities, counties and towns are marked in disease mapping. The results showed that there were significant regional differences of mortality rates for transportation accidents and suicides, but no significant differences for fall accidents.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.1159-1160
• /
• 2006

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, this has raised potential problems of network protection on electrical power system. One of the numerous problems is an Island phenomenon. There has been an argument that because the probability of islanding is extremely low it may be a non-issue in practice. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an island can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficient to cause a trip, plus the time required to execute the trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. And, third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an island. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. So the verification of anti-islanding performance is strongly needed. In this paper, the authors propose the improved RPV method through considering power quality and anti-islanding capacity of grid-connected three-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"). And the simulation and experimental results are verified.

• Journal of Convergence Society for SMB
• /
• v.5 no.4
• /
• pp.5-10
• /
• 2015

With the advance of ICT, understanding the condition of network and analysing network monitoring have become an important issue. On the TCP/IP network, SNMP is the typical protocol that catches the condition of network by using polling method. If polling method is implemented for a long period, to catch the change of the condition of the network is not easy. On the other hand, in case of short-term polling, even if it could catch the condition of the network in real time, responsive messages to results of the polling cause the increase of traffic and therefore burden the network. There have been studies to control the overhead of responsive messages by controlling the polling period. However, not considering the characteristics of an agent, and running randomly, they cannot decrease the overhead although they would have an instant effect. This paper suggests an efficient polling method that decreases the traffic overhead of polling and catches the condition of the network in real time. Proposed method an polling for a short period and gave weight based on the characteristics of agents to catch the network condition, and a manager decided polling differentially based on the weight so that it decreased the overhead of polling traffic.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2007.09a
• /
• pp.118-127
• /
• 2007

SAW(Submerged Arc Welding) process is generally applied to a wide range of welding area in the fabrication of steel structure. This process has a good characteristic properties such as the high quality of welds and the high deposition rates, but in case of welding on a thick steel plate, it also has higher cold crack susceptibility than that of a thin steel plate. The purpose of this research is to find the main factor of crack generation and clarify the countermeasure for crack prevention, and then establish the optimum welding condition in a heavy thick steel plate. The results of this study are as follows, 1. The cause of crack generation is found the diffusible hydrogen penetrated into weld metal by decomposition of the remained moisture in SAW flux during welding. 2. For the removal of diffusible hydrogen, the raw materials of SAW flux are to be dehydrated at the high temperature in the initial manufacturing stage. 3. Mechanical properties of weld metal welded with the dehydrated SAW flux were evaluated very excellent, furthermore the weld metal has been proved to have low diffusible hydrogen content with 3.1ml /100g. 4. The weldability and quality welded with thick steel plates were improved by establishing the new optimum welding condition.

• Journal of the Korean Society for Railway
• /
• v.12 no.5
• /
• pp.793-799
• /
• 2009

Using transportations like railway, aviations and roads have been increasing continuously. Traffic accidents have been increasing as well. To prevent or lessen these accidents become a big issue to solve. Therefore, more enforced safety levels are being required to meet. In railway field, continuous efforts of railway safety are being executed to prevent traffic accidents. In present, railway accidents have been decreasing since subway accident happened in Daegu Subway in 2003. However, safety levels in railway field have not yet achieved as much as in advanced countries. Basic concept for enforced safety level in railway system is to prevent or minimize accidents by managing systems like related facilities, management method, organization, education. This is the same concept to minimize error rate in six sigma theory. In this paper, we are to apply six sigma techniques used in manufacturing industry to railway safety and go through ways to make more efficient railway safety system.

• Journal of KIISE
• /
• v.42 no.2
• /
• pp.145-154
• /
• 2015

This paper proposes an enhanced projection candidate selection algorithm to improve the performance of the existing path prediction algorithm. Various user path prediction algorithms have previously been developed, but those algorithms are inappropriate for a real-time and close user path prediction environment. To resolve this issue, a new prediction algorithm has been proposed, but several problems still remain. In particular, this algorithm should be enhanced to provide much faster processing performance. The major cause of the high processing time of the previous path prediction algorithm is the high time complexity of its projection candidate selection. Therefore, this paper proposes a new path fragment management structure and an improved projection candidate selection algorithm to improve the processing speed of the existing projection candidate selection algorithm. This paper also shows the effectiveness of the algorithm herein proposed through a comparative performance evaluation.

• Journal of the Korean Magnetics Society
• /
• v.22 no.6
• /
• pp.221-227
• /
• 2012

High performance permanent magnets have become the subject of considerable attention because of the potential applications in the traction motors of hybrid and electric vehicles and wind generators. Nd-Fe-B magnets have attracted considerable interest due to a large maximum energy product. However, Nd-Fe-B magnet cannot be used in high temperature (${\sim}200^{\circ}C$) applications due to the thermal degradation of coercivity. Therefore, the development of high coercivity Nd-Fe-B permanent magnet is a challenging issue. In case of high coercivity Nd-Fe-B permanent magnet, an increment in the intrinsic coercivity can be easily achieved by substituting Nd atoms with Dy or Tb atoms. However, these heavy rare-earth elements are known to cause a decrease in remanence due to the antiferromagnetic coupling between Dy and Fe atoms. In addition, Dy is relatively expensive and being limited in quantity. Hence, a new technology that can increase the coercivity of Nd-Fe-B sintered magnet using only a small amount, or even, no amount of heavy rare-earth elements is being investigated. This article describes the research trend in reducing the heavy rare-earth elements in Nd-Fe-B magnets.

• The Journal of Korean Medicine
• /
• v.36 no.1
• /
• pp.33-44
• /
• 2015

Objectives: The aim of this study was to understand the characteristics of herbal-drug-associated adverse events (AEs) reported in the internet newspaper articles and to take a countermeasure against the safety issue of herbal drugs. Methods: We searched the internet newspaper articles published from 2010 to 2014 in the 3 major portal sites in Korea, NAVER, DAUM, and GOOGLE. Search terms were the Korean words equivalent of 'herbal drug' and 'side effects'. Informations on the type and characteristics of suspected herbal drugs, AEs, and the patient records were extracted from the articles reporting the herbal-drug-associated AE occurred in Korea. Results: From 8,806 articles, a total of 36 AEs were found. The most frequently reported age group was 20s, and women outnumbered men. Obesity was the most common cause of administration. Doctors of Korean medicine clinic were the most commonly referred prescribers and purchasing route (11 cases). The most frequently mentioned medicinal herb was Ephedra sinica (7 cases) and the most commonly reported AEs were abdominal pain (8 cases), dizziness (6 cases), diarrhea (5 cases), and vomiting (5 cases) were followed in order. Ten cases were judged as serious AEs, and the others were not. Conclusions: Current customers demand health care providers to offer them sufficient information on the safety of herbal drugs. To satisfy their requirements, physicians of Korean medicine should be able to explain, predict, prepare, recognize, and deal with the herbal-drug-associated AEs. We propose an establishment of pharmacovigilance system for herbal medicine, in which doctors of Korean medicine are participated as important personnel, to collect and analyze the related AEs and offer credible information on the safety of herbal drug.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.6 no.2
• /
• pp.28-33
• /
• 2010

As a part of license renewal for the continued operation of Wolsong unit 1, the periodic safety review report was submitted near the end of design lifetime, 2012, and now is under reviewing. Major components of primary system such as pressure tubes, feeder pipes and so on are being replaced and many components of secondary system are also being repaired. So the license renewal of Wolsong unit 1 is expected to be acquired without significant issues. But on the other hand, steam generators of Wolsong unit 1 had the good performance and therefore the replacement and repair for the steam generator are not needed. Recently it is reported that some cracks were detected in a few of european steam generator with Alloy 800 tubes and the cause of cracks was the outer diameter stress corrosion cracking(ODSCC) due to the concentration of chemical impurities on the outer surface of tube. Accordingly the overall review on this issue was performed. The long-term operation is likely to results to form the concentration mechanism for the tube corrosion as the sludge build-up in the secondary side of steam generator and the crack in the crevice between tube and tube-sheet and expansion transitions is apt to be occurred. In this paper, the history of steam generator inspection and operation of Wolsong unit 1 are reviewed and the reliability of steam generator tube is evaluated and the steam generator aging management program for Wolsong unit 1 is introduced.

• The Journal of the Korea Contents Association
• /
• v.13 no.7
• /
• pp.311-321
• /
• 2013

Health is an essential element of human living and participation in society. Due to its significance, government tries to maintain the healthy life of tis people by providing health care and enhancement systems that focus on health welfare. Despite such efforts, there is still a loophole in the public system. The health problem in socially disadvantaged people, especially single mothers, becomes the cause of poverty, and the poverty again results in the poor health conditions. That is why the private sector became interested in this health issue. In this case study about the participants in the healthcare support programs for single mothers in the private sector, their experience and change related on participation in the programs were investigated in depth. As results, the following significance and quantitative performance in supporting the health right for single mothers were explored. Since single mothers could not have cared for their health because their duty for not only parenting but also family's living, th participants thought that they attained good fortunes and their own social networks. Moreover, their life attitude changed to active and their family relationship was also improved as they got out of ambiguous anxiety of health and attained self confidence.