• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.376-383
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• 2008

Generally a return current plane(RCP) of high speed digital and analog part is partitioned. This is achieved in order to decrease the noise interference between subsystem in PCBs(Printed Circuit Boards). However, when the connected signal line exists between each subsystem, this partition will cause unwanted effects. In a EMI(Electromagnetic Interference) point of view, the partition of the return current plane becomes a primary factor to increase the radiated emission. Component bridge(CB) is used for the way of maintaining radiated emission, still specific user's guide doesn't give sufficient principle. In a view point of EMI, design principle of multi-CB using method will be analyzed by measurement. And design principle of noise mitigation will be provided. Generally interval of multi-CB is ${\lambda}/20$ ferrite bead. In this study, When multi-CB connection is applied, design principle of ferrite bead and chip resistor is proved by measurement. Multi-connected chip resistance$(0{\Omega})$ is proved to be more effective design method in the point of EMI.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.366-375
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• 2008

Generally a return current plane(RCP) of high speed digital and analog part is partitioned. This is achieved in order to decrease the noise interference between subsystem in PCBs(Printed Circuit Boards). However, when the connected signal line exists between each sub system, this partition will cause unwanted effects. In a circuital point of view, RCP partition has a bad influence upon signal integrity. In a EMI(Electromagnetic Interference) point of view, the partition of the return current plane becomes a primary factor to increase the radiated emission. Component bridge(CB) is usecl for the way of maintaining signal integrity, still specific user's guide doesn't give sufficient principle. In a view point of signal integrity, design principle of multi-CB using method will be analyzed by measurement and simulation. And design principle of noise mitigation will be provided. Generally interval of CB is ${\lambda}/20$ ferrite bead. In this study. When multi-CB connection is applied, design principle of ferrite bead and chip resistor is proved by measurement and simulation. Multi-connected chip resistance$(0{\Omega})$ is proved to be more effective design method in the point of signal integrity.

• Communications of Mathematical Education
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• v.32 no.3
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• pp.363-383
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• 2018

The subject of 'Mathematical Task Inquiry' was introduced newly in the curriculum revised in 2015. The subject is dealt with after completing the subject of 'mathematics' to be dealt with in the tenth grade. Its main content is comprised of the understanding and learning of the purpose and procedure of inquiry task and of study ethics, and its educational goal is to enforce the prior mathematical knowledge and to obtain the ability to select interesting topics that combine mathematics with other subjects. However the textbook of the subject does not exist, and teachers should handle with the subject with responsibility for their own ways. Because of this reason, this study is to develop an instruction model on project(task) inquiry model and materials. Namely, according to the model, students is guided to select and decide the subject of the task, and develop the task for themselves, solve it with peers in cooperation, and announce the solution and their feelings. During those students' exploration and activities, the role of teachers is to guide students to complete their work. By the way, in order to develop more creative tasks that is appropriate to their academic and cognitive level, this study conducted the experimentation for the subject of 9 students (6 girls and 3 boys), who are scheduled to advance to the 11 grade of J high school located in G domestic. The experimentation was consisted of three class and after the third class, the semi-structured interview was conducted immediately for the students.

• The Journal of the Korea Contents Association
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• v.8 no.4
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• pp.285-293
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• 2008

Internet addiction is currently regarded as a problem for its negative function in the information-oriented society. Particularly in cases of elementary schoolchildren in their growth period, it is very important to grasp the schoolchildren's conditions in advance and guide them on a systematic basis before they get into the habit of addiction to the Internet. For this purpose, several research papers have already discussed the seriousness of Internet addiction. This research is aimed at conducting a positive research work on to what extent such academic research results had affected educational fields, and also at what level the seriousness of Internet addiction is staying at the present moment. For this, this research conducted a survey of the Internet addiction level for fourth, fifth, and sixth graders totalling in 448 from one elementary school located within the jurisdiction of Gyeongsangbuk-do through the on-line system and questionnaires from March 31 to April 3, 2008. And also looked into the level of perception on Internet addiction for 29 teachers within the surveyed school. The results of this study show that 90.1 percent(408 children) of the surveyed children were a member of a general user group. Such aspects are thought to have resulted from some factors that functioned in a positive way, such as teachers' proper perception on Internet addiction and their proper guidance against this, and plenty of conversation at the children's homes, and the children's smooth relationship between their friends and teachers.

• The Korean Society of Law and Medicine
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• v.18 no.2
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• pp.47-73
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• 2017

Medical certificate is a document to demonstrate a patient's health status, made up and signed by a physician, dentist, or oriental physician who attended the patient. It serves as an evidence in many official process including civil or criminal law suit, especially for one's personal injury. The Korean legal system also acknowledges and protects the evidentiary function of medical certificate by mandating physicians etc. to issue medical certificate in good faith and only when they personally attended the patient, and by criminally punishing them when they do not comply with these legal requirements. There are some reasons, however, that medical certificates often do not reflect the true health status of the patient: When physicians attend the patient and collect information regarding the health status of the patient, their priority is and should be the most cost-effective way to meet the health needs of the patient. It does not necessarily correspond to the accurate examination of the health status of the patient. Even when the patient's report on the history of the illness or the injury seems suspicious, physicians might have to avoid disproving it because that kind of attitude might harm the rapport between the physician and the patient. All these can distort the perception of the physicians and this distortion can be reproduced in the medical certificate they made up. Some of these problems might be resolved or at least enhanced by introducing new form of medical certificate which would guide physicians to reveal the nature, factual and theoretical grounds, and the limit of their findings more accurately. Others, however, would not be able to address, because it stems from the conflict between the physician's primary duty, duty to be loyal to the patient's life and health, and his secondary duty to serve as a public or neutral witness on the health status of the patient, and when both values or duties conflict with each other, they should choose the duty to the patient sacrificing the duty to the public or the court.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.74-81
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• 2016

Because most of the passengers are not accustomed with onboard environments, it is very important to analyze and predict the behaviors' characteristics of passengers under disasters' conditions, and apply those results for making countermeasures. On this view point, this study focused on the walking characteristics of onboard-novices are tested and analyzed under blackout condition that has high possibility to happen. As a result, comparing to under normal lighting conditions, the waking times under blackout conditions are 155.8~247.1 % longer on full path, 56.9~331.7 % on corridors, 75.3~152.9 % on stairs, respectively. And under the same blackout conditions, walking times in cases of the exit guidance marks being attached on top side of walls saved times, like 21.6~24.0 % on full path, 37.7~58.9 % on corridors, 18.7~19.2 % on stairs, comparing to the cases of exit guidance marks being not attached. On the other hand, after tests under without exit guidance marks, 60.7% among respondents answered that internal structures like wall/stair (35.7 %) and handrail (25 %) are very helpful to decide way findings, and 28.6 % selected personal instincts is important. But 50 % responded that exit guide marks are effective to find ways, after the tests under with exit guidance marks.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.168-178
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• 2017

In order to prevent major and chemical accidents, some of the plants which would like to install and operate hazard chemicals handling facilities must submit Off-site Consequence Analysis due to recent arisen leak accidents since 2015. A lot of chemical industrials choose gas detectors as mitigation equipment to early detect gas vapor. The way of placement of gas detectors has two methods; Code-based Design(CBD) and Performance-based Design. The CBD has principles for gas detectors to be installed with consideration for the place that is expected to accumulate gas, and the leak locations according to legal standards and technical guidelines, and has a possibility to be unable to detect by these rules to locate gas detectors by vapor density information. The PBD has two methods; a Geographic Method and Scenario based Method. The Scenario-based Method has been suggested to make up for the Geographic Coverage Method. This Scenario-based Method draw the best optimum placement of gas detectors by considering leak locations, leak speed information, leak directions and etc. However, the domestic placement guidelines just refers to the CBD. Therefore, this study is to compare existing placement location of gas detectors by the domestic CBD with placement locations, coverages and the number of gas detectors in accordance with the Scenario-based Method. Also this study has measures for early detecting interest of Vapor Cloud and suitable placement of gas detectors to prevent chemical accidents. The Phast software was selected to simulate vapor cloud dispersion to predict the consequence. There are two cases; an accident hole size of leak(8 mm) from API which is the highst accident hole size less than 24.5 mm, and a normal leak hole size from KOSHA Guide (1.8 mm). Detect3D was also selected to locate gas detectors efficiently and compare CBD results and PBD results. Currently, domestic methods of gas detectors do not consider any risk, but just depend on domestic code methods which lead to placement of gas detectors not to make personnels recognize tolerable or intolerable risks. The results of the Scenario-based Method, however, analyze the leak estimated range by simulating leak dispersion, and then it is able to tell tolerable risks. Thus it is considered that individuals will be able to place gas detectors reasonably by making objectives and roles flexibly according to situations in a specific plant.

• Journal of the Korean School Mathematics Society
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• v.17 no.3
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• pp.359-384
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• 2014

The purpose of this study is inquire the reaction and adaptability of the mathematically gifted student, in the case of introduce learning materials based on GeoGebra in real class. The study program using GeoGebra consist of 'construction of fundamental figures', 'making animation with using slider tools' (graph of a function, trace of a figure, definite integral, fixed point, and draw a parametric curve), make up the group report after class. In detail, 1st to 15th classes are mainly problem-solving, and topic-exploring classes. To analyze the application effects of developed learning materials, divide students in four groups and lead them to make out their own creative products. In detail, guide students to make out their own report about mathematical themes that based on given learning materials. Concretely, build up the program to make up group report about their own topics in six weeks, after learning on various topics. Expert panel concluded that developed learning materials are successfully stimulate student's creativity in various way, after analyze of the student's activities. Moreover, those learning programs also contributed to the develop of the mathematical ability to thinking that necessary to writing a report. As well, four creative products are assessed as connote mathematically gifted student's creative thinking and meaningful elements in mathematical aspects.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.632-638
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• 2014

Nowadays, as part of an effort to increase the efficiency of propulsion shafting system, the revolution of the main diesel engine in CMCR(Contract Maximum Continuous Rating) is reduced whereas the stiffness of hull structure supporting the main diesel engine is relatively flexible. However, vibration problems related with resonant response of main diesel engine are increasing although top bracing is installed between the main diesel engine and the hull structures to increase natural frequency of engine body above CMCR to avoid resonant phenomenon. In this study, the dynamic characteristic of top bracing is reviewed by analyzing measuring results of general cargo ships which apply the hydraulic type instead of the friction type to control the natural frequency and the vibration of the engine body. Moreover, considering the vibration characteristic of the engine body and the hydraulic type of the top bracing by varying the number of top bracing, authors suggest the more effective way to control the vibration of the engine body despite of lower stiffness of the hull structure than in the past when the hydraulic type of top bracing is used.

• Journal of Environmental Impact Assessment
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• v.22 no.5
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• pp.455-466
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• 2013

The aim of this study is to seek application plans of National Ecosystem Survey database based on comparison and examination of feasible analysis methods for distribution characteristics of alien plants. In order to set up a correlation analysis method between alien plants and environmental factors, we had reviewed the 3rd National Ecosystem Survey guide book and consequently, two kinds of analysis method were tested. One was 1/25,000 scale map boundary based analysis and the other was representative mountain area based analysis. In this study we restricted the research area to select reliable surveyed database from whole "2011 National Ecosystem Survey flora database" according to two major criteria. First, an area defined by 1/25,000 scale map boundary and representative mountain area where the number of surveyed flora records should be within top 20%. Second, land cover map should also be built up inside that area. As a result, 25 map boundaries and 25 representative mountain areas were extracted to be analyzed. To limit a boundary for every representative mountain area we had analyzed distribution of environmental factors around that area by manual inspection with SPOT-5 remote sensed satellite image then designated 3km buffer zone from each alien plant location in that area. After then, naturalized index (NI) and urbanized index (UI) was calculated and correlations analysis was carried out. With the result of correlation analysis by map boundary only agricultural land area showed significant value of r (0.4~0.6, correlated) and the rest of factors did not. In the case of representative mountain area, the result showed that agricultural land, road and forest area showed significant value of r (0.6~0.8, highly correlated) which was corresponding to existing researches. Therefore, representative mountain area based method is preferable when using the alien plants database of National Ecosystem Survey for species distribution analysis. And also, considering the way of database utilization is strongly suggested at the first stage of survey planning for promoting active use of national ecosystem survey database.