• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.4
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• pp.401-409
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• 2012

Ultrasonic testing are far superior to other nondestructive tests for detecting the disbond interface which occurred in adhesive interface. However, a solid rocket motor consisting of a steel case, rubber insulation, liner, and propellant poses many difficulties for analyzing ultrasonic waves because of the superposition of reflected waves and large differences in acoustic impedance of various materials. Therefore, ultrasonic tests for detecting the disbond interface in solid rocket motor have been applied in very limited areas between the steel case and rubber insulation using an automatic C-scan system. The existing ultrasonic test cannot detect the disbond interface between the liner and propellant of a solid rocket motor because most of the ultrasonic waves are absorbed in the rubber material which has low acoustic impedance. This problem could be overcome by analyzing the resonance frequency from the frequency spectrum using the ultrasonic resonance method. In this paper, a new technique to detect the disbond interface between the liner and propellant using ultrasonic resonance characteristics is discussed in detail.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.182-194
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• 2009

This study was conducted to evaluate health status and to propose health protection measures of irregular plant construction workers in Yoesu National Industrial Complex (YNIC). The status of safety and health management was examined in five areas including safety and health education, work environment monitoring, health examination, health management record, and personal protective equipment (PPE) for plant construction workers. The safety training rate for plant construction workers was reached high at 91%, The training was mostly consisted of safety accident related things, but training on hazardous materials was found to be insufficient. Workplace monitoring results showed that the compliance rate for work environment for irregular construction workers was 54% and workplace monitoring during turnaround (TA) period with high risk of exposure to hazardous agents has not been implemented. While 61.4% of irregular workers received the general health examination but only 36.8% received the special health examination. The special health examination was found to be conducted only upon welders from 2-3 years ago. The issue of health management record upon irregular construction workers was not being implemented. In case of PPE, basic safety protective equipments such as safety shoes, safety belt, safety helmet were being supplied well while the supply rate of respirator for organic vapor was relatively low at 40%. Based on this study, two suggestions to maximize the utilization of the current safety and health program were made while boosting its effectiveness in protecting workers' health. First, the role of owners (petrochemical plant) related to safety and health should be strengthened. Second, in consideration of the characteristics of construction workers who usually engage in short term employment and frequent movement, community based health management organization is suggested that can overcome such structural problem and carry out the implementation of health examination and sustained health management.

• Toxicological Research
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• v.24 no.4
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• pp.253-261
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• 2008

Allergic asthma is a worldwide public health problem and a major socioeconomic burden disease. It is a chronic inflammatory disease marked by airway eosinophilia and goblet cell hyperplasia with mucus hypersecretion. Mouse models have proven as a valuable tool for studying human asthma. In the present report we describe a comparison of mouse asthma models. The experiments were designed as follows: Group I was injected with ovalbumin (OVA, i.p.) on day 1 and challenged with 1% OVA (aerosol exposure) on days $14{\sim}21$. Group II was injected on day 1, 14 and aerosol-immunized on days $14{\sim}21$. Group III was injected on day 1, 14 and immunized by 1% OVA aerosol on days $18{\sim}21$. We assessed asthma induction by determining the total number of white blood cells (WBC) and eosinophils as well as by measuring cytokine levels in bronchoalveolar lavage fluid (BALF). In addition, we evaluated the histopathological changes of the lungs and determined the concentration of immunoglobulin E (IgE) in serum. Total WBC, eosinophils, Th2 cytokines (IL-4, IL-13) and IgE were significantly increased in group I relative to the other groups. Moreover, histopathological studies show that group I mice show an increase in the infiltration of inflammatory cell-in peribronchial and perivascular areas as well as an overall increase in the number of mucus-containing goblet cells relative to other groups. These data suggest that group I can be a useful model for the study of human asthma pathobiology and the evaluation of existing and novel therapeutic agents.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.71-80
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• 2011

Almost all Drivers who are not familiar with local areas usually rely on road signs equipped along the roadways. The road signs in Korea present the name of the city along the driver’s direction. The consistency of guided name on the road-signs is important for drivers. The discordances among road signs frustrate drivers particularly when the drivers are confused with whether or not they are in the right direction. There are several studies focusing on the continuity of information on the road signs. Most of the researches, however, do not suggest the objective way but diagnose present problem. Applying the Analytic Hierarchy Process (AHP), we evaluate the impact of information on road signs and select the candidate information considering the score and limited number of information. We also suggest the reasonable spatial influence area of road sign information using geo-spatial analysis. From this study, we expect that the director in charge of selecting information can make decision reasonably without difficulties of choosing information.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1107-1108
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• 2006

As expanding municipal and industrial areas since started the economic development plan in earnest in 1970's, the water resource, mainly river surface water has been seriously polluted. Nevertheless, being upgraded in their treatment technologies for the drinking water, the safety has been issued one of crucially social problem in Korea. The water authorities has tried to improve the quality such as amending the drinking water quality standard to be monitored; hazardous chemicals and microorganis have been added and now 55 items, before 47 items, since in 2002. The Water Authorities of Seoul, the capital city of Korea, planned to assess the safty of drinking water quality after amended the standard. This study was conducted to assess the risk due to polluted chemicals including 21 heavy metals, VOCs, pesticides, PAHs, DBPs and organic chemicals among the regulated items. The risk assessment were undertaken hazard identification, exposure assessment, dose-response assessment and risk characterization. For the exposoure assessment, tap water, bottled water and purified water were sampled and analyzed in February, 2004. Risk characterization of detected chemicals was categorized into carcinogenecity and noncarcinogenecity, and estimated the excess of carcinogens and compapared with the reference dose (RfD) of noncarcinogenns. The excess risk of carcinogens from samples were considered comparatively in the acceptable levels; $10^{-6}$ for cancer risk and hazard quotient (HQ) 1.0 for noncancer risk. The deteced levels were estimated in $10^{-5}{\sim}10^{-6}$ of cancer risk and below 1.0 of HQ of noncancer risk. While three kinds of water were determined within the acceptal levels, DBPs were detected in tap water and purified were and some undesireable chemicals such as more fluoride detected rather than the quality stanadard. For the drinking water safety, it shoud be continuously monitored, assessed and managed as well risk communiction between the authoritis and public.

• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.577-596
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• 2018

ASEAN countries consist of vast coastal areas and thousands of islands that are vulnerable to the effects of climate change on sea level rise. It is believed that this will play an important role in reducing greenhouse gas emissions globally in order to minimize the damage suffered by ASEAN countries. To overcome this issue, biofuels have been used to minimize the impact on the environment by replacing fossil fuels and to reduce greenhouse gas emissions. In those cases of United States, Brazil and Europe, where biofuels are highly utilized, research, development and investment in this field have been actively conducted in the past. In ASEAN countries, however, it has not been a long time since the biofuel policies were established. To overcome this problem, we investigated the renewable fuel policy in the United States, Brazil and the European Union. Based on this, we suggested the utilization plan and prospect of biofuel policy in ASEAN countries.

• Journal of agricultural medicine and community health
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• v.16 no.1
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• pp.40-47
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• 1991

Musculoskeletal disorders are a major cause of occupational disabilities. Approximately thirty percent state that the major reason for an inability to work is a musculoskeletal problem. A farm work is associated with increased stress and trauma to joints. Chronic overuse injuries are a result of stresses that exceed the body's adaptive or healing capabilities. They can occur in bone, tendons and muscle-tendon-bone junctions. The aim of the investigation was to the study the frequency of pain, ache, and discomfort in the musculoskeletal system among farmers, to find possible correlations between these symptoms and various working positions and different working actions. A questionnaire was answered by 138 farmers. Of those who answered the questionnaire 82% had pain and discomfort from back, shoulders, arms in orders, The result showed that musculoskeletal pain predominate in the farming seasons, and of those who had pain and discomfort 89% thought that farm works had a correlation with the pain and discomfort of musculoskeletal system. But only 17% of quationnaire were put to periodic medical examinations, and 50% of those who had pain and discomfort consulted a doctor. Education in effective pain treatment should therefore be intensifide to ascertain that farmers in rural areas have satisfactory knowledge of the musculoskeletal pain as a chronic overuse syndrome.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.10 no.1
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• pp.47-56
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• 2003

Purpose: This study was done to provide information about issues of clinical competency from the perspective of new graduate nurses and to make suggestions for improving undergraduate education programmes. It was also done to clarify learning experiences between fundamentals of nursing and the other major areas of nursing. Method: For this study, 7 new graduates and 8 experienced nurses participated. The data were collected through in-depth interviews and analysed in terms of Strauss and Corbin's grounded theory methodology. Result: Core category and main categories, were delineated. Clinical nursing competency was found to be a dynamic process with each participant actively engaged in acquiring problem solving ability in diverse clinical settings. These findings have value in understanding the embedded meaning of clinical nursing competency. Conclusion: Therefore, the educational programs reflecting the experience of new nursing staff should be developed.

• Convergence Security Journal
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• v.14 no.3_2
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• pp.93-98
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• 2014

In a recent survey conducted among Seoul citizens, the demand for crime prevention in addition to settlement of environmental problem and traffic system improvement turned out to be the highest. In particular, the demand for prevention of crimes in residential areas was higher than any other items. The crime rates are especially high in deteriorated residential districts, which indicates the relation between crimes and physical environmental factors. In other words, proper measures for surroundings can prevent crimes. While there may be various ways to keep the residents from crimes safely, CPTED, a crime preventive method in a way of improving the physical surroundings is one of the most noteworthy solutions. The principles of CPTED involves the basic principles such as Natural Surveillance, access control, and securing of territoriality and additional principles of strengthening of Activity Support and Maintenance & Management. This study aims to present a method to lower and prevent crime occurrences by applying the principles of CPTED in deteriorated Apartment Housing in the middle of a city.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.1
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• pp.60-70
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• 2007

Statement of problem: The cement-type abutment would be needed for the reduction of its body in order to correct the axis and to assure occlusal clearance. In the case of intraoral preparation, there is a potential risk that generated heat could be transmitted into the bone-implant interface, where it can cause deterioration of tissues around the implant and failed osseointegration. Purpose: The purpose of this study was to assess the difference of the heat transmitting effect on external and internal connection implant types under various conditions. Material and method: For evaluating the effects of alternating temperature, the thermocoupling wires were attached on 3 areas of the implant fixture surface corresponding to the cervical, middle, and apex. The abutments were removed 1mm in depth horizontally with diamond burs and were polished for 30 seconds at low speed with silicone points using pressure as applied in routine clinical practice. Obtained data were analyzed using Mann-Whitney rank-sum test and Wilcoxon / Kruskal-Wallis Tests. Result: Increased temperature on bone-implant interface was evident without air-water spray coolant both at high speed reduction and low speed polishing (p<.05). But, the difference between connection types was not shown. Conclusion: The reduction procedure of abutment without using proper coolant leads to serious damage of oral tissues around the implant irrespective of external and internal connection type.