• International Journal of Highway Engineering
• /
• v.15 no.1
• /
• pp.143-154
• /
• 2013

PURPOSES: Design of approach roads of rest areas in highway has many drawbacks such as geometric design elements. There has been traffic accidents occured in these approach roads of rest areas. Thus, design criteria is required in order to protect accidents from being occurred. In case of Korea, geometric structure design criteria of entry facilities, such as toll-gate, interchange, junction etc was established. However there are no presence in a detailed standards for geometric structure of the rest area which affiliated road facilities. METHODS: In this study, analytic on accidents was carried out in regards to the entry of geometric structure of resting areas by utilizing a sight survey and an investigation research of traffic accidents. The survey was targeting 135 general service areas. Collisions with physical channelization and safety facilities occurred due to speeding, rapid entry, and etc at the entrance nose section. At the entrance connector roads, accidents caused by speeding, negligence, over-operation of handle of drivers were main reason of accidents. Discriminant analysis were conducted about geometric elements to distinguish influencing factors for traffic accidents. the lengths and access angles of the entrance connector roads were regarded as to have the high relation with traffic accidents. RESULTS: After classifying the design section of resting areas' entry as well as derive design elements on each section, a speed measurement by targeting entry of rest areas and car behavior surveys were performed, then each element's minimum standard was derived through the analyses. According to the speeds at the starting/end point of entrance connector road, the range of the junction setting angle of the entrance connector road is defined as $12^{\circ}{\sim}17^{\circ}$ and the connector length model was suggested. CONCLUSIONS: Suggest improvement plans for existing rest areas that can be applied realistically. This should be corresponded to the standards of entry and exit of developed rest areas.

• Journal of Environmental Health Sciences
• /
• v.48 no.2
• /
• pp.86-95
• /
• 2022

Background: As high concentrations of uranium and radon have been detected in some areas in Korea, it is considered necessary to investigate natural radioactive materials in the Gwangju area. Objectives: This study aimed to identify the hydrochemical characteristics of groundwater in Gwangju and investigate the distribution characteristics of uranium and radon, which are naturally radioactive substances. Methods: To determine the uranium and radon concentrations in groundwater according to the geology of the Gwangju area, we measured 62 groundwater wells. A geological distribution map of uranium and radon content was prepared for this study. Results: The groundwater type, defined using a Piper diagram, was mainly Ca-HCO₃. The concentration of uranium in the groundwater ranged from 0 to 29.3 ㎍/L, with a mean of 3.3 ㎍/L and a median of 0.9 ㎍/L. The median concentration of uranium in groundwater was highest in alluvium, granitic gneiss, and biotite granite (classified by geological unit), in that order. The concentration of radon in the groundwater ranged from 4.8 to 313.2 Bq/L, with a mean of 75.6 Bq/L and a median of 59.6 Bq/L. The median concentration of radon in groundwater was highest in biotite granite, alluvium, and granitic gneiss, in that order. As a result of the correlation analysis of groundwater in the study area, there was no significant correlation between uranium and radon. Conclusions: In this study area, uranium was shown to be far below the concentrations allowed by drinking water quality standards, but radon concentrations exceeded drinking water quality monitoring standards in 11% of the samples. It was judged that appropriate measures, such as the installation of radon reduction facilities, will be required after a thorough review of high-concentration radon detection sites of in the research area.

• Progress in Superconductivity
• /
• v.6 no.1
• /
• pp.56-63
• /
• 2004

We consider design factors for a SQUID sensor array to construct a 52-channel magnetocardiogram (MCG) system that can be used to measure tangential components of the cardiac magnetic fields. Nowadays, full-size multichannel MCG systems, which cover the whole signal area of a heart, are developed to improve the clinical analysis with high accuracy and to provide patients with comfort in the course of measurement. To design the full-size MCG system, we have to make a compromise between cost and performance. The cost is involved with the number of sensors, the number of the electronics, the size of a cooling dewar, the consumption of refrigerants for maintenance, and etc. The performance is the capability of covering the whole heart volume at once and of localizing current sources with a small error. In this study, we design the cost-effective arrangement of sensors for MCG by considering an adequate sensor interval and the confidence region of a tolerable localization error, which covers the heart. In order to fit the detector array on the cylindrical dewar economically, we removed the detectors that were located at the corners of the array square. Through simulations using the confidence region method, we verified that our design of the detector array was good enough to obtain whole information from the heart at a time. A result of the simulation also suggested that tangential-component MCG measurement could localize deeper current dipoles than normal-component MCG measurement with the same confidence volume; therefore, we conclude that measurement of the tangential component is more suitable to an MCG system than measurement of the normal component.

• Journal of Korean Home Economics Education Association
• /
• v.30 no.1
• /
• pp.65-77
• /
• 2018

The purpose of this study is to investigate how to strengthen the formation of relationship competence through the lesson in the housing of the 2015 revised Technology Home Economics curriculum. In order to achieve this goal, we analyzed curriculum documents, achievement standards of curriculum, achievement standards of assessment, and assessment standards of the 2015 revised Technology Home Economics curriculum. Then, we analyzed whether or not the curriculum could be truly reflected in the school site by comparing and analyzing verbs of the assessment standards and curriculum content system. In addition, we suggested the plan to ensure that 2015 revised curriculum can be implemented well by proposing a method of teaching-learning and assessment standards to cultivate the formation of relationship competence among the housing lessons. The results of the study are as follows. First, the 2015 revised Technology Home Economics curriculum are categorized into three subject competences according to the content, but eventually show the content is not mutually exclusive with the three subject competences. It can be said to demonstrate the characteristics of human ability development, that is, one learning can't be related only to one competency. Second, it is difficult to reflect the assessing subject competencies system in school education, where evaluation is carried out based on the assessment standards. This is because the skills of the 2015 revised curriculum documents are partially reflected in the assessment standards. Therefore, this study shows that teachers need to cultivate various subject competencies. In order to overcome the fundamental limitations of the competency-centered curriculum, it is necessary to retrain the teachers as well as to improve teaching and learning methods for operating the curriculum.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.4B
• /
• pp.261-266
• /
• 2012

In this study, soil environmental impact assessment using risk-based approach was compared with that using concentration-based approach. For this, heavy metal contaminant exposure was characterized in an abandoned mine area. According to the estimated carcinogenic and non-carcinogenic risks, soil ingestion was identified as the most dominant exposure pathway. When contaminant concentrations exceeded the Korean Soil Contamination Warning Standards, their corresponding risk values also exceeded the Total Soil Risk Standard. Even the cases of satisfying the Korean Soil Contamination Warning Standards mostly showed higher risk levels than the Total Soil Risk Standard, re-confirming a more sensitivity of the risk-based assessment than concentration-based assessment. However, the in-depth analysis of the estimated non-carcinogenic risk values revealed a few cases for soil contact pathway showing contaminant concentrations higher than the Korean Soil Contamination Warning Standards although their non-carcinogenic risk values satisfied the level of Hazard Index Standard. The findings from this study support a necessity of shifting policy paradigm from concentration-based approach into risk-based approach for reliable risk assessment in abandoned mine areas, and also suggest a necessity of further fundamental studies regarding risk factors and standards.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.37 no.2
• /
• pp.99-105
• /
• 2017

Many composite materials are used in the aerospace industry because of their excellent mechanical properties. However, the nature of aviation exposes these materials to high temperature and high moisture conditions depending on climate, location, and altitude. Therefore, the molecular arrangement chemical properties, and mechanical properties of composite materials can be changed under these conditions. As a result, surface disruptions and cracks can be created. Consequently, moisture-impregnating defects can be induced due to the crack and delamination of composite materials as they are repeatedly exposed to moisture absorption moisture release, fatigue environment, temperature changes, and fluid pressure changes. This study evaluates the possibility of detecting the moisture-impregnating defects of CFRP and GFRP honeycomb structure sandwich composite materials, which are the composite materials in the aircraft structure, by using an active infrared thermography technology among non-destructive testing methods. In all experiments, it was possible to distinguish the area and a number of CFRP composite materials more clearly than those of GFRP composite material. The highest detection rate was observed in the heating duration of 50 mHz and the low detection rate was at the heating duration of over 500 mHz. The reflection method showed a higher detection rate than the transmission method.

• The Mathematical Education
• /
• v.44 no.2 s.109
• /
• pp.281-295
• /
• 2005

To evaluate students properly in mathematics, it is essential to clarify and specify the object of study. Proper assessment tools are also needed coupled with an effective assessment method. The assessment tools have to be reasonable and trustworthy. Conducting the assessment should always produce fair and positive results and effectiveness. Establishing standards for the student evaluation competence of mathematics teachers should satisfy such objectives. Referring to the previous study suggested by Korea Institute' of Curriculum & Evaluation(KICE), this study classified the elements of capacity for evaluation competence into the general assessment, the assessment content understanding, and the assessment conduct & application areas. The specific elements of each area are established as standards. At last, 13 standards were suggested and summarized. to describe the math teachers' student evaluation competence.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.4
• /
• pp.349-354
• /
• 2013

The non-destructive testing using infrared thermography is extended to a variety of industries and non-destructive testing of welds using infrared thermography is also in progress in various ways. Currently, a non-destructive testing of electrical resistance spot welds which is mainly used is Radiography Testing. This study detected area of spot welds nugget using optical-infrared thermography. In the results, it is possible for detecting defects of nugget in a short period of time using pulse-infrared thermography.

• Journal of the Korean Society of Safety
• /
• v.33 no.1
• /
• pp.62-65
• /
• 2018

The rapid progress toward the 4th industrial society has led to possibilities of fire increase. It is pointed out that, though initial fire suppression is emphasized, the current legal systems do not sufficiently recognize the importance of initial fire suppression. In order to resolve this, problems of the current legal systems and regulations, as well as fire-fighting facilities to be equipped according to the size of specific fire-fighting objects, were diagnosed. Also, suggestions for improvement were provided through comparative analysis with relevant laws and technical regulations of Korea and other countries. According to fire safety standards such as NFPA, IMO, ISO, and Russian standards, automatic fire extinguishers are to be installed as per the adaptability criteria of fire extinguishers and automatic fire extinguishers. In Korea, the "Act on Fire Prevention and Installation, Maintenance, and Safety Control of Fire-fighting Systems" cover the types and scope of fire fighting facilities that include specific fire protection objects, such as electric room, power room, and substation room. This study has identified that, in case of a place with a floor area of less than $300m^2$, the installation requirement is not clearly specified. Therefore, in this study, fire extinguishing equipment and automatic fire extinguishing equipment to be added for each sub-use application are proved to have fire extinguishing performance of Class A, Class B, and Class C, respectively. In view of the fact that, in overseas standards, all space except containing such materials as Deep fire, metal fire and peroxide, can be installed with fire fighting equipment, a legal system for specifying the capacity units of fire fighting apparatus by application is, in this study, proposed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.6
• /
• pp.1253-1259
• /
• 2005

This paper dealt with the development of surge protection devices (SPDs) that can protect high speed computer network devices from overvoltages caused by switching operations or lightning surges. The designed SPD is a form of hybrid circuit which is composed of a gas tube having large current diverting capability, high response bi-directional avalanche diodes, and fast recovery diodes to reduce insertion loss on high frequency domain. Surge protection and signal transmission characteristics of the fabricated SPD was tested according to the international standards, IEC 61000-4-5 and IEC 61643-21. From the test results, the SPD is satisfied with the international standards and the high cut-off frequency was 204 MHz. Also, the SPD showed a good performance without an insertion loss on a field test of 100 Mbps class Local Area Network.