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Performance Enhancement Study of a Final Clarifier by the Optimum Design of Inlet and Baffle Condition (유입구 및 정류벽 최적설계에 의한 최종 침전지 성능 개선 연구)

  • Kim, Hey-Suk;Shin, Mi-Soo;Jang, Dong-Soon;Jung, Sung-Hee;Gang, Dong-Hyo
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.2
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    • pp.177-183
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    • 2005
  • The effluent quality is directly affected by the separation of biological solids in a final clarifier because the majority of discharged $BOD_5$ and SS are virtually dependent on the results of biological solids in the sedimentation tank effluent. If a final clarifier is effectively designed and operated, the desired goal of clarification for wastewater can be achieved together with the cost reduction in the treatment of wastewater. To this end flow characteristics and the removal efficiency of SS are numerically investigated especially by the change of the inlet position and the installation of baffle to improve the performance of a rectangular final clarifier. The 2-D computer program developed in a rectangular coordinates has been successfully validated against experimental residence time distribution(RTD) curves obtained by tracing radio-isotope. The lowering of the inlet position weakens the density current and induces the settling of SS in the front zone of a clarifier. Thus the decreased traveling distance of the sludge increases the removal efficiency of SS in the effluent. The inlet baffle installed in the front region of clarifier prevents the short circuiting flow and induces to flow into the dense underflow, which eventually improves the effluent quality. In the case of lower inlet position, however, installation of baffle results in degradation of effluent quality. Consequently it is strongly recommended that in-depth numerical study be performed in advance for optimizing a clarifier design and retrofitting to improve effluent quality in a final clarifier.

A STUDY ON THE FRACTURE RESISTANCE AND CHARACTERISTICS OF TEETH IN CLASS II CAVITY RESTORATIONS (2급(級) 와동(窩洞) 수복시(修復時) 치아파괴(齒牙破壞) 저항성(抵抗性) 및 귀열양상(龜裂樣相)에 관(關)한 연구(硏究))

  • Joo, Ik-Nam;Park, Sang-Jin;Min, Byung-Soon;Choi, Ho-Young
    • Restorative Dentistry and Endodontics
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    • v.13 no.2
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    • pp.337-348
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    • 1988
  • The purpose of this study was to examine the fracture strength and characteristics of teeth with MOD cavity preparation. Freshly extracted sound maxillary premolars were cleaned and stored in normal saline solution $37^{\circ}C$ for 72 hours before experiments. The roots of teeth were embedded in a self-curing resin, and the exposed crown were maintained in a vertical position by a modelling wax in a brass ring. The MOD cavities were prepared with No. 57 carbide bur under high speed to a depth of 2.0mm and a width of 2.0mm(Fig.1). All the prepared teeth specimens were divided into 7 groups according to the mode of cavity form and restorative materials (Table 1, 2): Group I, unpreapred, intact teeth as control Group II, prepared cavity without restoration Group III, prepared teeth restored with amalgam Group IV, prepared teeth restored with composite resin (P-10) Group V, prepared teeth with beveled enamel margins restored with composite resin (P-10) Group VI, prepared teeth restored with light-cured composite resin (P-30) Group VII, prepard teeth with beveled enamel margins restored with light-cured composite resin (P-30) After placement of restorations, all of the specimens were stored in water at $37^{\circ}C$ for 72 hours before testing. All of the specimens were tested on the Instron Universal Testing machine (No. 6025) in order to evaluate the strength of fracture. One metal ball 5.0mm in diameter contacting the specimens parallel to the occlusal surface was used to in this study (Fig. 1). The fracture characteristics of the specimens were examined with naked eye and in the scanning electron microscope (JSM-20). The results obtained from this study were as follows: 1. The mean fracture strength was the highest in group VI and that in group II was the lowest. 2. The progress of crack of teeth propagated into the pulp cavity. 3. In case of the group of the restored teeth, the crack occurred to be accompanied with cuspal fracture. 4. The crack of restored teeth was initiated along the pulpo-axial line angle of the cavity.

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Free-Surface Effects on a Fin Attached to a Submerged Body (잠수체 벽에 부착된 핀의 자유표면 효과에 관한 실험적 연구)

  • Kim, S.M.;Lee, S.J.;Lee, C.M.
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.1
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    • pp.27-39
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    • 1996
  • The effects of free surface and a strut on the lifting characteristics on a fin attached at the mid-chord of the strut are investigated experimentally in a circulating water channel. Variation of lift force on the fin is investigated with respect to free stream velocity(V), angle of attack of the fin(${\alpha}$) and ratio of the submergence depth of the fin to the chord of the fin(H/C). Attentions are focused on the lifting characteristics of the fin at shallow depths of submergence. Visualization of the free surface deformation along the strut and of the streamline about the fin is made in order to examine the inflow angle to the fin. Lift force on the fin alone i.e. in absence of the strut is also measured to investigate the difference in lifting characteristics of the fin caused by the strut. The results show that lift forces over the fin are largely affected by a free surface in the case of small submergence ratios(HiC<3.0). For HiC>5.0, the effects of the free surface are negligibly small. The inflow angle to the fin is significantly influenced by the strut and flow speed at the shallow depths of submergence. The deformation of the free surface is largely governed by the waves generated by the strut. However, for small submergence depths, the effects of the fin are found also significant.

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An Analysis of the Course Fulfillment Change in Fisheries Business Administration Curriculum with Business Education Accreditation (경영교육인증에 따른 수산경영학 교과과정 및 학업이수의 변화 분석과 과제)

  • Lee, Dong-Ho
    • The Journal of Fisheries Business Administration
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    • v.45 no.2
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    • pp.39-59
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    • 2014
  • Recently the rapid changes of the social environment make both university and every each department should have to renovate and adjust all of the educational components. The most dominant and issuable change of business administration education is the Business Education Accreditation which was certified by the KABEA(Korean Association of Business Education Accreditation). And the only two department of fisheries business administration which in Gyeongsang National University and Pukyong National University has been accredited recently. Though The department of fisheries business administration in Korea has been influenced by that Accreditation, there is few research and analysis on educational change. So it is very important that research on the curricular constitution and change of the curriculum for considering the its own effect and influence. This paper aims to explore the curricular constitution, change and course fulfillment of fisheries business administration after the business education accreditation based on the case of the department of fisheries business administration in Gyeongsang National University. The analysis of fisheries business administration change will help develop sustainable curriculum and give more guideline for identifying the core of fisheries business administration. The method of analysing that in this research has adopt the social network analysis(SNA) and automated software tool which is the most dominant technique in contents analysis including the Krkwics and Pajek. The SNA is evaluated that most popular, rigorous and firm methodology for analyzing, examining and revising some concepts or objects in the context of semantics. The result of this study shows that the ratio of fisheries business administration class has been decreased but still the most fulfilled course. And English mediated class has been avoided though that sort of the class has been increased. In the view point of course fulfillment, it has been potential and inefficient problems that some classes that including financial related and accounting related class would not been accomplished appropriately. The findings of a graduate depth interview which has been done about 4 years for understanding that student show that there's some recognition gap of fisheries business administration in staffs of human resource management. And the level of job satisfaction in fisheries business still somewhat low and even worse the chance of recruitment also unsteady.

Performances and Limitations of the Health Community Organization Project in 148 Village, Gangbuk-gu (강북구 148 마을 건강주민운동사업의 성과와 한계)

  • Hong, Jong won;Park, Woong-Sub;Kim, Sang-A;Kim, Nam Jun
    • Journal of agricultural medicine and community health
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    • v.42 no.3
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    • pp.155-167
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    • 2017
  • Objectives: The purpose of this study was to examine the performances and limitations of health community building project of 148 village in Gangbuk-gu, Seoul on community health organization perspective. Methods: we conducted a qualitative study using both a systematic review of this project and in-depth interviews with the operators who had worked for the project from January 2012 to December 2012. Results: In this project, activists worked by gathering the opinions of the residents and focusing on their growth. The residents themselves established a community health care plan. Based on social determinants of health, they continued projects to solve residents' needs. A variety of programs were activated by providing a health cafe, which was an alternative public participation health promotion space that was not a clinic or a public health center. As the various entities gathered, there were difficulties related to interests and role sharing, and there were limitations such as the fact that the performance and limit of the pilot project could not be clearly predicted beforehand. Conclusions: This case suggested that new possibility of health and medical movement, approaching health issues by the way of community organization principle. Through the health community building project as community health organization perspective is expanded, health promotion effect will be created in the whole society.

A Study on the Career Development Path of Standard Expert for the 4th Industrial Revolution (제4차 산업혁명에 대응하는 표준전문가 경력경로 연구)

  • Hwang, Yunwon;Song, Yongchan
    • Journal of Digital Convergence
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    • v.15 no.12
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    • pp.101-109
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    • 2017
  • This study seeks the career development path for standard professional manpower training to respond to the $4^{th}$ industrial revolution based on the analysis of overseas professional manpower training from USA and EU. Based on the cases of USA & Europe and in-depth interview, this study suggested a professional manpower training system to cultivate both general expert and specialists at the same time. The study suggested that there is a need to train standard professional manpower with convergence professionalism that can combine the detailed fields in accordance with general and specific field. As for the program helping career development of professional manpower, job transfer/circulation system, career counseling, mentoring were suggested. Also, the study suggested that the training requires foundations such as various constructions of certification system of standard professional manpower, securing instructors with ability to conduct standard education wand professionalism, and empowerment through reeducation of current standard related manpower. This study is limited as it is a descriptive study based on domestic and overseas literature review and overseas case analysis in seeking career development path for professional manpower training. There is a need to diversify empirical research that could review the validity of the study result related to the $4^{th}$ industrial revolution and standard professional manpower.

Development of Jeju Local Food Tour Package and Economic Value Estimation based on Contingent Valuation Method (제주 향토음식을 활용한 음식관광상품 개발 및 CVM을 적용한 경제적 가치 평가)

  • Ahn, So-jung;Yoon, Ji-young
    • Journal of the East Asian Society of Dietary Life
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    • v.26 no.4
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    • pp.346-358
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    • 2016
  • Local food reflects the identity and image of a specific region. It is also a core element for determining tourists' experience of a region. The purpose of the present study was to develop a Jeju food tour package using local foods and estimate the economic value of the suggested tour package using Contingent Valuation Method (CVM). Five food tour packages were developed by researchers. In order to modify and measure the value of each package, an expert panel survey was conducted, and 'package 5' was selected as a food tour scenario for the tourist survey. A survey was conducted on 295 domestic tourists who visited Jeju within the past 10 years in order to evaluate the economic value and feasibility of the Jeju food tour package. A total fo 72.9% of respondents answered that they were willing to pay for the Jeju local food tour, and the willingness to pay (WTP) range was between ₩45,000 and ₩105,000. The primary factors correlated with WTP was food expenses, followed by leisure experience expenses, interest in local foods, education level, visit frequency and age. The WTP of the Jeju local food tour was calculated with the significantly affected factors using stepwise regression model. The result of the present study reveal that tourists' WTP increased with higher food expenses, education level, and age group. The average value of food expenses, education level, and age were substituted into the formula derived from the regression analysis, yielding 58,385.752 KRW as the WTP. The expected economic value created by exploiting the Jeju local food tour was shown to be 700 billion KRW per year, calculated by multiplying WTP of the food tour packages by the number of tourists. This study examined the feasibility and plan of the food tour package to increase the economic value of Jeju local food. In the case of the culinary tour program based on Jeju local food launching, the estimated economic effect was great. Therefore, in-depth research to merchandise the Jeju local food tour program is needed.

Trail Deterioration and Managerial Strategy on the Ridge of the Baekdudaegan : A Case of the Trail between Namdeogyusan and Sosagogae (백두대간 마루금 등산로의 훼손실태와 관리방향 :남덕유산-소사고개 구간을 대상으로)

  • 권태호;이준우;김동욱
    • Korean Journal of Environment and Ecology
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    • v.18 no.2
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    • pp.175-183
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    • 2004
  • They are raising the necessity to prepare the conservational management strategy for the trail on the ridge of the Baekdudaegan where deterioration of natural environment along the trail as the rapid increase of visitors to the Baekdudaegan. The purpose of this study, followed after the Kwon and Lee(2003), is to research the deterioration condition of the trail between Namdeogyusan and Sosagogae on the Baekdudaegan. To accomplish the purpose, not only trail condition such as altitude, entire width, bare width, maximum depth and slope of trail, but also deterioration types of trail were surveyed at the total 182 points for 32.3km in length. Furthermore, impact rating class, which could be effective means to check the step and extent of deterioration process, was judged on each points of trail. Results informs us that the deterioration condition of the trail between Namdeogyusan and Sosagogae is not reached the level of grave concern yet, but some points and sections of trail are in urgent need of the integrated and organized maintenance. And some managerial strategies of trail were proposed in connection with the maintenance for trail on the Baekdudaegan ridge.

The Analysis of Korean Fair Trade Commission's Judgemental Cases of Cartels in Telecommunications and Media Industry (통신 및 미디어 산업에서의 카르텔에 대한 심결사례 연구 행정지도, 카르텔유형, 경쟁제한성 판단, 카르텔 제재를 중심으로)

  • Oh, Jeong-Ho
    • Korean journal of communication and information
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    • v.46
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    • pp.627-670
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    • 2009
  • This study analyzed Korean Fair Trade Commission's judgemental cases of cartels in telecommunications and media industry and presented the following results. First, cartels were formed frequently in multi-channel broadcasting industry, telecommunications industry, movie industry, and newspaper industry. In addition, price-fixing were observed in almost all subfield of telecommunications and media industry. Second, administrative guidance facilitated more opportunities for collusion in the telecommunications industry than in the media industry. Third, the telecommunications and media industry, similar to overall domestic industries, had a high proportion of hard-core cartels. Fourth, the depth of judgemental case in evaluating agreements among competitors was generally low, even though detail evaluations were found in the cases of large fines. Fifth, the overall level of sanctions was relatively low.

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Changes of the surface hardness and the light transmittance of PET film by ion implantations (이온 주입에 의한 PET막의 표면경도변화 및 광 투과도 변화)

  • 박재원;이재형;이재상;장동욱;최병호;한준희
    • Journal of the Korean Vacuum Society
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    • v.10 no.2
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    • pp.241-246
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    • 2001
  • Single or dual ion implantations were performed onto the transparent polyethylene terephthalate(PET) sheet, and the surface hardness and the light transmittance in the visual-UV range were examined. Nanoindentation showed that the surface hardness was the highest at about 50 nm depth from the surface and was increased by about 3 times when nitrogen ions were implanted with energy and dose of 90 keV and $1\times10^{15}\textrm{/cm}^2$ respectively. When dual ions such as He+N and N+C ions were implanted into PET, the hardness was increased even more than the case only N ions were implanted. Especially, when PET were implanted with N+C dual ions, the surface hardness of PET increased 5 times more as compared to when implanted with N ions alone. The light at the 550 nm wavelength(visual range) transmitted more than 85%, which is close to that of as-received PET, and at the wavelength below 300 nm(UV range) the rays were absorbed more than 95% as traveling through the sheet. implying that there are processing parameters which the ion implanted PET maintains the transparency and absorbs the UV rays. It can be considered that the increase in the hardness of polymeric materials is attributed to not only cross linking but also forming hard inclusions such as hard C-N compounds, as evidenced by the formation of the highest hardness when both N and C ions are implanted onto PET.

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