• Journal of dental hygiene science
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• v.5 no.1
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• pp.7-12
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• 2005

This study was conducted to compare and analyze 877 cases of health insurance claims from the first half of 1999 requested to the dental centers of local health centers in rural areas and 510 identical cases from the first half of 2003. It was purposed to understand the trend of rural residents' visits to local health centers and to use the collected data as the basis needed for the vitalization of local dental cares to efficiently improve Korean citizens' dental hygiene. The results were shown as below: 1. The sexes of the visitors were fairly evenly distributed for each year. 2. Among the total of 39 types of diseases treated, 1999 had 31.9% of visits for 'Gingivitis and periodontal diseases' with 25.4% from ages between 10 and 19, for statistically attentive results. On the other hand, 2003 had 46.5% of visits for 'Oral examination' with 52.9% from ages between 0 and 9, for statistically attentive results. 3. For the distribution of age groups, majority in 1999 made visits for dental caries, gingivitis and periodontal disease, whereas majority in 2003 were for oral examination, dental caries, gingivitis and periodontal disease.

• Journal of Life Science
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• v.23 no.4
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• pp.602-608
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• 2013

The multifaceted role of chronic inflammation in multistep carcinogenesis has been extensively investigated and well documented. Periodontal diseases are associated with multifactorial agents, including bacterial endotoxins and the generation of an inflammatory response, indicating that poor oral health is associated with a variety of systemic diseases. The association between poor oral health, chronic inflammation, smoking, and increased alcohol consumption as risk factors for tumorogenesis is well established. More recently, associations between oral health and tooth loss and gastric, lung, and pancreatic cancers have been explored, with some studies pointing to smoking and oral health as a common link with an increased risk for malignant disease. In addition, epidemiological studies consistently indicate increased risks of various cancers with periodontal disease or poor oral condition caused by oral bacteria, which may activate alcohol- and smoking-related carcinogens locally or act through chronic inflammation. Appropriate oral care is vital in preventing cancer, as well as many other diseases. Thus, research on the correlation between oral care and periodontal inflammation and cancer is required. This review highlights the association between oral health and the risk of certain malignancies, such as periodontal disease-associated chemoprevention of inflammation" in this sentence.

• Journal of Life Science
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• v.26 no.9
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• pp.999-1006
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• 2016

This paper studies an infection of norovirus and astrovirus in outbreaks in Korea. In March 2016, gastroenteritis outbreaks occurred in Busan. 522 students of three departments at university D had meeting at a restaurant near the university. Some of them had symptom such as diarrhea, vomiting. Epidemiological, laboratory and environmental investigations were performed to identify the agents of the outbreaks. Fecal specimens were collected from 35 students and 7 food handlers to identify causative viral agents. Norovirus genogroup GI and GII were detected from diarrhea patients. Astrovirus was also detected from some of them. In particular, these outbreaks were the first occurrence associated with astrovirus in Busan. Total of 42 samples were collected, and 24 samples resulted in positive to norovirus (16 cases) and astrovirus (8 cases). To identify the molecular genetic information of norovirus, we carried out sequences analysis of the detected strains. Norovirus genotypes were classified into GI.3, GI.4, GII.4, GII.13, GII.17 and GII.21. Astrovirus genotypes were seven astrovirus type 5 and one astrovirus type 2. We performed environmental investigation about water at the kitchen, but norovirus and astrovirus were not detected. The statistical analysis was conducted to evaluate the association between illness and risk factors. The results of this study may contribute to accumulate more the epidemiological data and develop the public health and hygiene.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.434-440
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• 2011

In order to establish the guidance of management and safe use hazard substance, trend analysis of hazard substance in/on agricultural products reported by press for 5 years (2005-2009) was performed. Data for the analysis collected from the articles about hazard substances from web portals, newspapers and so on. The mostly detected harmful factors in/on agricultural products were pesticides residue and heavy metals by the reports by press for last 5 years. The number of detected pesticides was slightly increased from 14 to 34 through the passage of time but the number of cases reported by press was not increased. On the other hand, the number of accidents and reports related to heavy metals were highly increased from 3 to 13 and 42 to 112, respectively. 65 pesticides including chlorpyrifos were detected in domestic agricultural products for the 5 years. Frequently detected pesticides were chlorpyrifos, endosulfan, carbendazim, azoxystrobin, and procymidone. Pesticide residues were repeatedly detected on green vegetables such as a green perilla leaf, a lettuce, a leek, and spinach among crops.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.2-2
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• 1999

금속재료의 표면 특성을 높이기 위해서 여러 표면처리 방법들이 사용되어져 오고 있다. 그 중 용사법에 의한 코팅방법이 최근의 현저한 기술적인 진보와 새로운 용사재료의 개발 등에 의해 여러 분야에 널리 응흉되고 있다. 일반적으로 이 용사법에 의한 코팅층은 다리, 선박 등의 대형 구조물에 대한 내식성 향상뿐만 아니라 자동차 및 항공기 부품, 핵 반응기 등의 코팅부에 널리 이용되고 였다. 특히 해수분위기에서 주로 사용되는 설비의 내식성을 향상시킬 목적으로 사용되 는 알루마늄 및 아연 합금의 용사 코팅층은 대부분의 경우 건조한 분위기보다는 수분이 많은 수용액 환경 하에서 사용되므로, 사용 환경 중에서 용사피막의 내식성을 조사하는 연구가 요구되고 있다. 사용되는 환경하에서의 침지시험에 의한 방법도 중요하지만, 가속화된 전기화학측정에 의한 방법 또한 이용된다. 열용사법에 의한 코팅층의 전기화학적 특성을 알아보기 위해서 3.5 % NaCI 수용액 내에서 AI 5 5083 모재와 Al-2%Zn 합금의 용사 코팅층 각각에 대한, 그리고 AI 5083 모재 위 AI-2%Zn 용사층이 코팅된 경우에 대한 분극거동과 침지시간에 따른 부식전위 및 분극저항성의 특성변화, 표면의 임피던스특성 변화 등을 측정하였다. 이 결과 모재에 대한 코팅층의 희생양극성올 판단할 수 있고, 모재/코팅 사스템의 분극거동은 혼성전위이론(mixed-potential theory)에 의해 결정되었다. 용사 코팅층이 박리되어 모재가 일부 드러난 경우를 모사한 시험편올 제작하고, 시험편 표면의 각 위치에 따라 부식전위 분포를 측정하였다. 그리고 측정 데이터를 기초로 표면의 상태변화를 모사하여 용사코팅에 의한 표면에서의 방식전위분포를 시율레이션하였다. 이와 같은 표면에서의 방식전위분포 해석을 통하여, 코팅층의 희생양극성에 의한 모재의 방식범위를 판단할 수 있다.의 비저 항을 갖는 철 박막에서도 99.9% 순도의 철을 타켓으로 하여 증착된 막은 일반 저탄소 강을 타켓으로 하여 증착된 막보다 훨씬 낮은 부식속도를 보였다.TEX>$He/O_2/Ar/N_2$의 gas를 사용 한 atmospheric pressure plasma cleaning 과 $Ar/O_2$의 gas를 사용한 ICP cleaning에서 이 차전자방출계수(SEEC)가 약 1.5~2.5배 증가된 것을 알 수 있었다. 저지능 등을 평가하여 각 실험결과를 비교분석하여 보았다. 수록 민감하여 304 의 IGSCC 와 매우 유사한 거동을 보인다. 본 강연에서는 304 와 600 의 고온 물에서 일어나는 IGSCC 민감도에 미치는 환경, 예민화처리, 합금원소의 영향을 고찰하고 이에 대한 최근의 연구 동향과 방식 방법을 다룬다.다.의 목적과 지식)보다 미학적 경험에 주는 영향이 큰 것으로 나타났으며, 모든 사람들에게 비슷한 미학적 경험을 발생시키는 것 이 밝혀졌다. 다시 말하면 모든 사람들은 그들의 문화적인 국적과 사회적 인 직업의 차이, 목적의 차이, 또한 환경의 의미의 차이에 상관없이 아름다 운 경관(High-beauty landscape)을 주거지나 나들이 장소로서 선호했으며, 아름답다고 평가했다. 반면에, 사람들이 갖고 있는 문화의 차이, 직업의 차 이, 목적의 차이, 그리고 환경의 의미의 차이에 따라 경관의 미학적 평가가 달라진 것으로 나타났다.corner$적 의도에 의한 경관구성의 일면을 확인할수 있지만 엄밀히 생각하여 보면 이러한 예의 경우도 최락의 총체적인 외형은 마찬가지로 $\ulcorner$순응$\lrcorner$의 범위를 벗어나지 않는다. 그렇기 때문에도 $\ulcorner$순응$\lrcorne

• Geophysics and Geophysical Exploration
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• v.23 no.2
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• pp.97-114
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• 2020

Recently, many studies have been actively conducted on the application of machine learning in all branches of science and engineering. Studies applying machine learning are also rapidly increasing in all sectors of seismic exploration, including interpretation, processing, and acquisition. Among them, fault detection is a critical technology in seismic interpretation and also the most suitable area for applying machine learning. In this study, we introduced various machine learning techniques, described techniques suitable for fault detection, and discussed the reasons for their suitability. We collected papers published in renowned international journals and abstracts presented at international conferences, summarized the current status of the research by year and field, and intensively analyzed studies on fault detection using machine learning. Based on the type of input data and machine learning model, fault detection techniques were divided into seismic attribute-, image-, and raw data-based technologies; their pros and cons were also discussed.

• Journal of The Korean Association of Information Education
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• v.16 no.3
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• pp.327-336
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• 2012

The Korea government has recently announced "A Master Plan for Smart Education", including application of digital textbooks and composition of education system using cloud computing. Our education system in future circumstance, over the conventional e-learning methods, needs the smart education solutions which enable students to study and communicate on various types of devices. The ongoing government project related with the digital textbook has been performed as mid- and long-term goals, whereas PDF-based e-textbook project, similar to e-book model and, has been already completed for the short-term goal. For the purpose of improved future smart education circumstance, however, a specific strategy is required in the following areas: flexibility of format conversion and independency of original text sources among the multiple device platforms. Therefore, in this paper, we propose a standardization scheme for e-textbook format based on e-book structure. To do this, we survey trends in e-book technologies, and research on standardization of e-book format for digitalization of textbooks, based on the analysis of existing textbooks. Moreover, we produce an example e-book content using our proposed standard method. As a result, our approach can be applied to the future smart education circumstance, and we may say that it will be efficiently applicable to the long-term digital textbook project.

• Korean Business Review
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• v.11
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• pp.217-239
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• 1998

The intial public offerings(IPO) issued by going public must be decided duly and seriously. In these sense, this paper reviewed and analysed synthetically the theories and the empirical studies on the IPO. The implications about the empirical studies on the IPO in korea stock exchanges(KSE) are as follows: First, evaluating the IPO's intrinsic value, the issued firm's characteristics(style, scale, age, reevaluation and goodwill etc.) and business environments(industry, economic states, regulations and the relation with government etc.) will be considered. Evaluating the IPO's relative value, the stock price of firms registered in KOSDAQ market will be appreciated. Second, the income smoothing of an IPO listed in KSE accrued in the first and second years. Accordingly if auditors audit the accounting reports of firms to list in KSE by going public, they should more concern to the income smoothing on the accounting reports. Third, the information accuracy of investment banks and the qualities of auditors negatively correlated with the underpricing of an IPO. It is need to promote the information accuracy of investment banks and the qualities of auditors. Regulatory organizations support to promote the information accuracy of investment banks and the qualities of auditors. Forth, the investors interested in the IPO are to recognize the follows. (1) Relations between the underpricing of an IPO and the ratio of public participation, the issue price, the offer size, the insider ownership, the net asset value per share, the price decision system of an IPO. (2) An entrepreneurs who decided to bring his firm public would like to issue the IPO when company's operating conditions are good.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.368-377
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• 2000

This study was conducted to examine the recent developments in timber certification schemes at global level such as FSC certification and ISO 14001 system and to analyze their potential impacts on the Korean forest products trade. Data and information on standards and procedure of timber certification and certified forest lands were collected from relevant papers, statistics and reports published by regional and international organizations. In order to analyze the impacts on the Korean forest products trade, questionnaire survey to the affected parties was conducted on acknowledge of key words relating to environment and trade and on the additional amount of willingness to pay for a labeled timber from environmentally sound and sustainably managed forests. Quantities of certified timbers supplied would continue to increase due to lots of timber certification schemes developed and implemented at national, regional and global levels and growing interests in certification from many countries. Demand for certified timbers, however, is far from clear at this stage. The deciding factor would be consumer reaction to the certified products. In the short run, the timber certification would have a little impacts on forest products imports into Korean markets since domestic purchasers do not have much interests in environment related trade measures and their willingness to pay price premiums for certified timbers is not high. However, it could be expected that timber certification has negative impacts on exports of forest products, such as flooring and plywood, to developed European markets where timber certification is used as a trade barrier.

• Resources Recycling
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• v.26 no.3
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• pp.79-91
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• 2017

The core of Hydrogen Fuel Cell Vehicles (FCV) is polymer solid fuel cell (PEFC), and the core material that generates electrochemical electricity in the cell is platinum catalyst. Platinum is localized in South Africa and Russia, and the world production of Pt is about 178 tons per year, which is expensive and recycled. At present, the amount of Pt used in PEFC is $0.2{\sim}0.1mg/cm^2$. In order to reduce the price of the battery and increase the FCV supply, the target is to reduce the amount of Pt used to $0.05{\sim}0.03mg/cm^2$. $Pt-Pd/Al_2O_3$, Pt/C, Pt/GCB, Pt/Au/C, PtCo/C, PtPd/C, etc. by using polyol method using nano Pt, improved Cu-UPD/Pt substitution method and nano-capsule method, Have been researched and developed, and there have been reported techniques for improving the activity of Pt catalysts and stabilizing them. This paper investigates the production technology of nano-Pt and nano-Pt catalysts, recycling of spent Pt catalysts and application trends of Pt catalysts.