• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.2
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• pp.153-169
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• 2018

A submarine has a pressure hull that can withstand high hydraulic pressure and therefore, requires the use of highly advanced shipbuilding technology. When producing a pressure hull, periodic inspection, repair, and maintenance are conducted to maintain its soundness. Of the maintenance methods, Non-Destructive Testing (NDT) is the most effective, because it does not damage the target but sustains its original form and function while inspecting internal and external defects. The NDT process to detect defects in the welded parts of the submarine is applied through Magnetic particle Testing (MT) to detect surface defects and Ultrasonic Testing (UT) and Radiography Testing (RT) to detect internal defects. In comparison with RT, UT encounters difficulties in distinguishing the types of defects, can yield different results depending on the skills of the inspector, and stores no inspection record. At the same time, the use of RT gives rise to issues related to worker safety due to radiation exposure. RT is also difficult to apply from the perspectives of the manufacturing of the submarine and economic feasibility. Therefore, in this study, the Phased Array Ultrasonic Testing (PAUT) method was applied to propose an inspection method that can address the above disadvantages by designing a probe to enhance the precision of detection of hull defects and the reliability of calculations of defect size.

• Journal of the Korean society of biological therapies in psychiatry
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• v.24 no.3
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• pp.230-238
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• 2018

Objectives : Among adolescents, the proportion of daily smoking tends to increase with age, and does not return to the previous level. Therefore, we examined the factors associated with smoking frequency in a nationwide sample of Korean adolescents to help prevent the progression of smoking. Methods : Among 127,804 adolescents who participated in the 2016 and 2017 Korean Youth Risk Behavior Web-Based Survey, data from 7,781 adolescents who replied that they currently smoked were analyzed. According to the frequency of cigarette smoking, participants were classified into daily and non-daily smokers. Participants' socio-demographic characteristics, smoking behavior, and psychological problems including perceived stress, depressive mood, and suicidality were assessed. Results : There were 3,627(47.4%) daily smokers and 4,154(52.6%) non-daily smokers. Low parental educational level, and early smoking experience were positively associated with daily smoking. High academic achievement, and high socio-economic status were negatively associated with daily smoking. Daily smoking was positively associated with lower happiness, lower sleep satisfaction, and severe stress during the past 12 months. Factors affecting suicide attempts of smokers were sex, residential type, socioeconomic status, and early smoking experience. Conclusion : The results indicated that socially disadvantaged families, and smoking experience with young age influenced daily smoking among Korean adolescents. Daily smoking was associated with psychological problems including lower happiness, lower sleep satisfaction, and severe stress. Early smoking experience influenced suicidal attempts among Korean adolescent smokers. Early intervention for smoking cessation in this high-risk group may contribute to prevention of these psychiatric complications of smoking.

• Smart Structures and Systems
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• v.31 no.2
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• pp.101-111
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• 2023

Structural health monitoring (SHM) covers a range of damage detection strategies for buildings. In real-time, SHM provides a basis for rapid decision making to optimise the speed and economic efficiency of post-event response. Previous work introduced an SHM method based on identifying structural nonlinear hysteretic parameters and their evolution from structural force-deformation hysteresis loops in real-time. This research extends and generalises this method to investigate the impact of a wide range of flag-shaped or pinching shape nonlinear hysteretic response and its impact on the SHM accuracy. A particular focus is plastic stiffness (K_p), where accurate identification of this parameter enables accurate identification of net and total plastic deformation and plastic energy dissipated, all of which are directly related to damage and infrequently assessed in SHM. A sensitivity study using a realistic seismic case study with known ground truth values investigates the impact of hysteresis loop shape, as well as added noise, on SHM accuracy using a suite of 20 ground motions from the PEER database. Monte Carlo analysis over 22,000 simulations with different hysteresis loops and added noise resulted in absolute percentage identification error (median, (IQR)) in K_p of 1.88% (0.79, 4.94)%. Errors were larger where five events (Earthquakes #1, 6, 9, 14) have very large errors over 100% for resulted K_p as an almost entirely linear response yielded only negligible plastic response, increasing identification error. The sensitivity analysis shows accuracy is reduces to within 3% when plastic drift is induced. This method shows clear potential to provide accurate, real-time metrics of non-linear stiffness and deformation to assist rapid damage assessment and decision making, utilising algorithms significantly simpler than previous non-linear structural model-based parameter identification SHM methods.

• Journal of Korean society of Dental Hygiene
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• v.12 no.6
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• pp.1090-1100
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• 2012

Objectives : The purpose of this study is to investigate satisfaction in major and job esteem of college students in dental hygiene and nursing department according to volunteering. Methods : This study was used on a descriptive research design. participants of this study were 378 college students in some region from April 30th to May 21th. The collected data were analyzed by SPSS Program(version 20.0) using descriptive statistics. Results : Volunteering experience subjects was 24.3%, the subjects did not experience volunteering was 75.7% and volunteering related to major was 59.8% and it was 40.2% of unrelated volunteering. Volunteering experience by general characteristics was influenced significantly by grade(p= .000), major(p= .000), economic status(p= .007). Volunteering experience by major relevant characteristics of subjects was not influenced significantly. The major satisfaction by volunteering was a little higher on volunteering experience subjects than non-experienced subjects. and was not influenced difference significantly(p= .786). The job esteem by volunteering was higher volunteering experience subjects than non-experienced subjects and was influenced significantly(p=.005). Conclusions : College students majoring in the department of dental hygiene and nursing is somewhat lower the volunteering experience. The major satisfaction and job esteem of college students was influenced by volunteering. therefore, the need to plan ways to increase participation and provide information and opportunities is to invigorate the function of the volunteering service which is also considered as one of the functions of the university.

• Journal of Society of Preventive Korean Medicine
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• v.9 no.1
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• pp.65-75
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• 2005

This study aims to explore the difference in life satisfaction and daily activities of elderly solitaries through a survey conducted from May to June 2004 to 152 who hare moi the criteria set forth for this study. Used for the survey were such tools as 11 items of questions concerning characters of the subjects, Life Satisfaction and Daily activities(K-ADL). The outcomes could be summarized as follows: 1. The majority of 152 subjects are females, aged $70{\sim}79$, living in the urban areas, non-educated with miscellaneous religions(including non-believers), jobless, self-dependent (or living expenses, without leisure, with disease, suffering from sickness despite of treatment and, thus not self-confident in health. 2. The Life Satisfaction and K-ADL of all subjects appear in general to be good with $20.03{\pm}9.74$ and $8.25{\pm}2.74$, respectively. 3. The difference in Life Satisfaction by characters of the subjects is found significantly high in those who are females, living in rural area, educated, with religions and jobs, have diseases treated and currently confident in health. 4. The difference in K-ADL by characters of the subjects is significantly high for those who are older than 80, Buddhists, jobless, affordable with living expenses by themselves, sick currently and not confident in health. Thus, it is thought vastly important to help the elderly solitaries to realize quality of life by social (including family) assistance, economic self-reliance and health promotion and prevention. Measures drawn from the analysis into issues of the elderly solitaries from various aspects may definitely contribute to avoiding and complimenting the causes of various issues relating to the elderly people and to assisting them to cope with the problems in the highly geriatric society to come.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.611-631
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• 1999

Enviromental geochemisty and heary metal contamination at the Kongjueil mine creek were underaken on the basis of physicohemical properties and mineralogy for various kinds of water (surface, mine and ground water),soil, precipitate and sediment collected of April and December in 1998. Hydrgeochemical composition of the water samples are characterized by relatively significant enricant of Ca+Na, alkiali ions $NO_3$ and Cl inground and surfore water, wheras the mine waters are relatively eneripheral water of the mining creek have the characteristics of the (Ca+Mg)-$(HCO_3+SO_4)$type. The pH of the mine water is high acidity (3.24)and high EC (613$\mu$S/cm)compared with those of surface and ground water. The range of $\delta$D and $\delta^{18}O$ values (relative to SMOW) in the waters are shpwn in -50.2 to -61.6% and -7.0 to -8.6$\textperthousand$(d value=5.8 to 8.7). Using computer program, saturation index of albite, calcite, dolomite in mine water are nearly saturated. The gibbiste, kaolinite and smectite are superaturated in the surface and ground water, respectively. Calculated water-mineral reaction and stabilities suggest that weathing of silicate minerals may be stable kaolinite owing to the continuous water-rock reaction. Geochemical modeling showed that mostly toxic heavy metals may exist larfely in the from of metal-sulfate $(MSO_4\;^2)$and free metal $(M^{2+})$ in nmine water. These metals in the ground and surface water could be formed of $CO_3$ and OH complex ions. The average enrichment indices of water samples are 2.72 of the groundwater, 2.26 of the surface water and 14.15 of the acid mine water, normalizing by surface water composition at the non-mining creek, repectively. Characteristics of some major, minor and rate earth elements (Al/Na, K/Na, V/Ni, Cr/V, Ni/Co, La/Ce, Th/Yb, $La_N/Yb_N$, Co/Th, La/Sc and Sc/Th) in soil and sediment are revealed a narrow range and homogeneous compositions may be explained by acidic to intermediate igneous rocks. And these suggested that sediment source of host granitic gneiss colud be due to rocks of high grade metamorphism originated by sedimentary rocks. Maximum concentrations of environmentally toxic elements in sediment and soil are Fe=53.80 wt.% As=660, Cd=4, Cr=175, Cu=158, Mn=1010, Pb=2933, Sb=4 and Zn=3740 ppm, and extremely high concentrations are found are found in the subsurface soil near the ore dump and precipitates. Normalizing by composition of host granitic gneiss, the average enerichment indices are 3.72 of the sediments, 3.48 of the soils, 10.40 of the precipitates of acid mine drainage and 6.25 of the soils near the main adit. The level of enerichment was very severe in mining drainage sediments, while it was not so great in the soils. mineral composition of soil and sediment near the mining area were partly variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. reddish variable being composed of quartz, mica, feldspar, chlorite, vermiculite, bethierin and clay minerals. Reddish brown precipitation mineral in the acid mine drainage identifies by schwertmanite. From the separated mineralgy, soil and sediment are composed of some pyrite, arsenopyite, chalcopyrite, sphalerite, galena, malachite, goethite and various kinds of hydroxied minerals.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2533-2540
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• 2013

Background: Although screening is necessary where gastric cancer is particularly common in Asia, the performance outcomes of mass screening programs have remained unclear. This study was conducted to evaluate cost-effectiveness outcomes of the national cancer screening program (NCSP) for gastric cancer in South Korea. Materials and Methods: People aged 40 years or over during 2002-2003 (baseline) were the target population. Screening recipients and patients diagnosed with gastric cancers were identified using the NCSP and Korea Central Cancer Registry databases. Clinical outcomes were measured in terms of mortality and life-years saved (LYS) of gastric cancer patients during 7 years based on merged data from the Korean National Health Insurance Corporation and National Statistical Office. We considered direct, indirect, and productivity-loss costs associated with screening attendance. Incremental cost-effectiveness ratio (ICER) estimates were produced according to screening method, sex, and age group compared to non-screening. Results: The age-adjusted ICER for survival was 260,201,000-371,011,000 Korean Won (KW; 1USD=1,088 KW) for the upper-gastrointestinal (UGI) tract over non-screening. Endoscopy ICERs were lower (119,099,000-178,700,000 KW/survival) than UGI. To increase 1 life-year, additional costs of approximately 14,466,000-15,014,000 KW and 8,817,000-9,755,000 KW were required for UGI and endoscopy, respectively. Endoscopy was the most cost-effective strategy for males and females. With regard to sensitivity analyses varying based on the upper age limit, endoscopy NCSP was dominant for both males and females. For males, an upper limit of age 75 or 80 years could be considered. ICER estimates for LYS indicate that the gastric cancer screening program in Korea is cost-effective. Conclusion: Endoscopy should be recommended as a first-line method in Korea because it is beneficial among the Korean population.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.6
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• pp.227-237
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• 2015

From January 2013 to October 2015, weed invasion control techniques was tested in the test road of Jungbunaeryuk expressway so as to collect preliminary data for the management methods of the upper exterior banking of expressway shoulders. Then, monitoring was conducted and its results are as follows. Mat (sheet), solidifying agent, and mulching (wood chips) were applied for the test and their initial effects of preventing weed invasion were all excellent. It was found that the homogeneity of the wood chip mulching method needs to improve. In the mat method and the mulching method were found to have the most excellent economic feasibility and aesthetics, respectively. The covering degree was found to be the highest at 80% in the control site, followed by the wood chip site at 20% and the solidifying agent site and the non-woven fabric site at 5% each. As for species diversity, the control had the largest variety of species. Two years after the construction, many different species of plants invaded and were growing. Plants including weed didn't tend to invade the slopes applied with non-woven fabric. In addition, weed didn't invade the solidifying agent site and the aesthetics of the upper exterior banking of expressway shoulders was found to be excellent. The wood chip site was found to require consistent management for preventing weed invasion. The mat (sheet) site, the solidifying agent site, and the wood chip mulching site were found to have excellent weed prevention effects. As time passed, the mat (sheet) site and the solidifying agent site showed better weed prevention effects. However, they need consistent monitoring for further application.

• Journal of the Korean Professional Engineers Association
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• v.14 no.2
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• pp.52-61
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• 1981

In Korea Small-medium Companies Constitutes 96.5% of all of the mining and manufacturing industries, about 35.7% of the total production of value added business, an average of 35% of the actual export of industrial goods and 47.6% of employment since present at the end of 1979. Now then Small-medium Industry Companies organization style constitutes 78.6% of a form of private company and 81.2% of the total on an small scale under 50 persons inregular employee. Specially, the trouble of business management of the mining and manufacturing Companies in Korea are constituted average 28.3% of production management ill the worst trouble of business management from 1973 to 1979 and small-medium industry Companies are the same of about more than 30% of production management in the trouble of business management. In this cases, the status of production management is effected by small-medium industry companies are the style of non-system and non-organization, but then 13parts in production management operations have the many trouble problems. In this circumstances a change for the better of production management operations in small medium industry companies are suggested the application effects and achievement points of production management, it is suggested a kind of variety and a small quantity, production management system of small-medium industry Company. And then Industrial Engineering technics is applied systematic route and the company grow more than better its physical condition for the improve productivity applied system approach for production management. There for the chapter 4-5 of this paper treats of a rational production management system approach, it make a emphatic major point of high level of economic growth of small medium Industry enterprise.

• Korea Journal of Hospital Management
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• v.19 no.4
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• pp.57-68
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• 2014

Since the introduction of National Health Insurance(NHI) in 1977, it has grown rapidly and contributed to extend patient's access to the health care services. However, limited coverage for health care services of NHI has been ongoing challenge and private health insurance(PHI) has been rising as an alternative source of enhancing coverage and saving out-of-pocket(OOP) expenditure for patients. In this study, after controlling for socio-demographic, economic, health related variables, we identified the patients' healthcare utilization and subsequent OOP expenditure depending on their PHI enrollment and their enrollment types(fixed benefit, indemnity, fixed benefit plus indemnity). Data were collected from the 2010 Korean Health Panel. The unit of analysis was a member of household(n=13,324). Of the 13,324 cases, 70.7% of patients held PHI, in detail, fixed benefit(47.0%), indemnity(3.6%), fixed benefit plus indemnity(20.1%). Major findings showd that patients who enrolled in PHI used more outpatient services(outpatient visit, number of physician visit, number of examination) and spent more OOP expenditure than non-PHI patients. There were also differences of healthcare utilization and OOP expenditure among the types of PHI. In addition, PHI patients used more inpatient services(inpatient use, number of hospitalization, LOS), but there was no significant difference between PHI and non-PHI patients with regard to the OOP expenditure. Thus, we could not find any distinct relationship between the types of PHI and patients' tertiary hospital use. Policy-makers should need careful political deliberation for monitoring the effect of PHI on health care utilization and subsequent expenditure not only to improve patients' coverage but also to save their OOP expenditures.