• Title/Summary/Keyword: Direct Problem

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Surface characteristics and stability of implants treated with alkali and heat (알칼리와 열처리에 의한 임플란트의 표면 특성 및 골유착 안정성에 관한 연구)

  • Song, Yun-Seok;Cho, In-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.46 no.5
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    • pp.490-499
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    • 2008
  • Statement of problem: Bioactive materials must have the ability to spontaneously form a bone like apatite layer on their surface and induce direct biochemical bonding to bone. A simple chemical treatment via alkali and heat has been revealed to induce bioactivity in titanium. Purpose: The purpose of this study was to evaluate the surface characteristics and stability of alkali and heat treated implants. Material and methods: Specimens were divided into three groups; group 1 was the control group with machined surface implants, groups 2 and 3 were treated with alkali solutions and heat treated in the atmosphere and vacuum conditions respectively. The surface characteristics were observed with FESEM, XPS, TF-XRD and AFM. Stability was evaluated with the resonance frequency analysis, periotest and removal torque values. One-way ANOVA and Duncan test were used for statistical analysis. Results: 1. Groups treated with alkali and heat showed similar characteristics. Groups 2 and 3 showed high compositions of Na ions on the surface with sub-micron sized pores compared to group 1. Group 2 showed mixed compositions of anatase and rutile with superior contents of rutile. 2. Resonance frequency analysis : The ISQ of group 2 showed significantly higher values than that of groups 1 and 3 at 12 weeks. The ISQ of groups 1 and 2 showed significant increase after 4 weeks, and the ISQ of group 3 increased significantly after 2 and 4 weeks respectively (P < .05). 3. Periotest: The PTV of groups 1 and 2 showed significant decrease after 4 weeks, and the PTV of group 3 showed significant decrease after 2 and 4 weeks respectively (P < .05). 4. Removal torque analysis: The removal torque value of group 2 was significantly higher than those of groups 1 and 3 at 2, 4 and 8 weeks. The removal torque values of groups 1 and 3 showed increase at 4 and 12 weeks, but the removal torque value of group 2 showed increase after 4 weeks (P < .05). Conclusion: An oxide layer with appropriate crystal structure and amorphous sodium titanate layer can be obtained on titanium implants through alkali and heat treatment in the atmosphere, and even alkali and heat treatment in vacuum conditions, provided a bioactive surface containing sodium. These surface layers can be considered to be effective for enhancement of osseointegration and reduction of healing period for implant treatment.

Study on Public Awareness of establishing Marine Protected Areas - Case Study of Guimaras Province, Philippines using Contingent Valuation Method (해양보호구역의 설정에 대한 대중인식도 연구 - 조건부 가치측정법을 이용한 필리핀 기마라스주의 사례)

  • Kim, Tae-Goun
    • Journal of Navigation and Port Research
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    • v.38 no.6
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    • pp.663-672
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    • 2014
  • In Korea and the Philippines, as well as all over the world, with the recognition of the importance of marine ecological resources, the marine protected areas(MPA) have been established and managed to protect and preserve these resources. While the number of marine protected areas for marine ecological resources protection has been increased, there is main problem that the most of MPAs do not achieve their intended management objectives. the effective management. Because of the positive and negative impacts on local communities and fishermen as direct stockholders, there has been ongoing debate on the pros and cons of implementing MPAs. Accordingly, this research conducted a case study of establishing Marine Protected Areas in Guimaras, Philippines because Philippines fisheries code of 1998 (Republic Act 8550), which is enacted to manage, conserve and protect fishery resources, obliged local governments to designate no less than 15% of jurisdictional municipal water as fisheries resource protection areas for a long time. To do this, a dichotomous-choice contingent-valuation survey was conducted in the two municipalities of Guimaras, Philippines to investigate public opinion in debates over MPAs and to estimate willingness to pay (WTP) for MPAs to protect and conserve marine habitats for fishery resources. Because of the expected economic costs by prohibiting fishing activities within the establishing newMPA, 58.7% of respondents thought the costs should be compensated, but 91.4% respondents voted in favor of increasing MPAs for fisheries resources as a protective measure. Finally, with Contingent Valuation Method(CVM), the aggregate mean WTP (375.5ha) of San Lorenzo and Sibunag residents in Guimaras Province, Philippines for establishing the additional MPA in their municipality waters was estimated to $1,046,791. Therefore, these findings could be used as a valuable data for establishing effective management plan of MPAs in Korea.

What happens after IT adoption?: Role of habits, confirmation, and computer self-efficacy formed by the experiences of use (정보기술 수용 후 주관적 지각 형성: 사용 경험에서 형성된 습관, 기대일치, 자기효능감의 역할)

  • Kim, Yong-Young;Oh, Sang-Jo;Ahn, Joong-Ho;Jahng, Jung-Joo
    • Asia pacific journal of information systems
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    • v.18 no.1
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    • pp.25-51
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    • 2008
  • Researchers have been continuously interested in the adoption of information technology (IT) since it is of great importance to the information systems success and it is also an important stage to the success. Adoption alone, however, does not ensure information systems success because it does not necessarily lead to achieving organizational or individual objectives. When an organization or an individual decide to adopt certain information technologies, they have objectives to accomplish by using those technologies. Adoption itself is not the ultimate goal. The period after adoption is when users continue to use IT and intended objectives can be accomplished. Therefore, continued IT use in the post-adoption period accounts more for the accomplishment of the objectives and thus information systems success. Previous studies also suggest that continued IT use in the post-adoption period is one of the important factors to improve long-term productivity. Despite the importance there are few empirical studies focusing on the user behavior of continued IT use in the post-adoption period. User behavior in the post-adoption period is different from that in the pre-adoption period. According to the technology acceptance model, which explains well about the IT adoption, users decide to adopt IT assessing the usefulness and the ease of use. After adoption, users are exposed to new experiences and they shape new beliefs different from the thoughts they had before. Users come to make decisions based on their experiences of IT use whether they will continue to use it or not. Most theories about the user behaviors in the pre-adoption period are limited in describing them after adoption since they do not consider user's experiences of using the adopted IT and the beliefs formed by those experiences. Therefore, in this study, we explore user's experiences and beliefs in the post-adoption period and examine how they affect user's intention to continue to use IT. Through deep literature reviews on the construction of subjective beliefs by experiences, we draw three meaningful constructs which theoretically have great impacts on the continued use of IT: perceived habit, confirmation, and computer self-efficacy. Then, we examine the role of the subjective beliefs on the cognitive/affective attitudes and intention to continue to use that IT. We set up a research model and conducted survey research. Since IT use implies interactions among a user, IT, and a task, we carefully selected the sample of users using same/similar IT to perform same/similar tasks, to exclude unwanted influences of other factors than subjective beliefs on the IT use. We also considered that the sample of users were able to make decisions to continue to use IT volitionally or at least quasi-volitionally. For each construct, we used measurement items recognized for reliability and widely used in the previous research. We slightly modified some items proper to the research context and a pilot test was carried out for forty users of a portal service in a university. We performed a full-scale survey after verifying the reliability of the measurement. The results show that the intention to continue to use IT is strongly influenced by cognitive/affective attitudes, perceived habits, and computer self-efficacy. Confirmation affects the intention to continue indirectly through cognitive/affective attitudes. All the constructs representing the subjective beliefs built by the experiences of IT use have direct and/or indirect impacts on the intention of users. The results also show that the attitudes in the post-adoption period are formed, at least partly, by the experiences of IT use and newly shaped beliefs after adoption. The findings suggest that subjective beliefs built by the experiences have deep impacts on the continued use. The results of the study signify that while experiencing IT in the post-adoption period users form new beliefs, attitudes, and intentions which may be different from those of the pre-adoption period. The results of this study partly demonstrate that the beliefs shaped by the behaviors, those are the experiences of IT use, influence users' attitudes and intention. The results also suggest that behaviors (experiences) also change attitudes while attitudes shape behaviors. If we combine the findings of this study with the results of the previous research on IT adoption, we can propose a cycle of IT adoption and use where behavior shapes attitude, the attitude forms new behavior, and that behavior shapes new attitude. Different from the previous research, the study focused on the user experience after IT adoption and empirically demonstrated the strong influence of the subjective beliefs formed in the post-adoption period on the continued use. This partly confirms the differences between attitudes in the pre-adoption and in the post-adoption period. Users continuously change their attitudes and intentions while experiencing (using) IT. Therefore, to make users adopt IT and to make them use IT after adoption is a different problem. To encourage users to use IT after adoption, experiential variables such as perceived habit, confirmation, and computer self-efficacy should be managed properly.

A Study on Qian Yi(錢乙)'s Medical Though (전을(錢乙)의 의학사상(醫學思想)에 관(關)한 연구(硏究))

  • Oh, Jun Hwan;Kim, Ki Wook;Park, Hyun Kook
    • The Journal of Korean Medical History
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    • v.14 no.2
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    • pp.109-152
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    • 2001
  • Throughout this paper, I adjusted the study of 'Qian Yi'(錢乙)'s Medical Thought, and the following is the summary. 1. 'Qian Yi' wrote 'Xiao Er Yao Zheng Zhi Jue'("小兒藥證直訣", edited by 誾季忠), and there were 'Shang Han Lun Zhi Wei'("傷寒論指微"), 'Ying Ru Lun', however those are loss of the record. 2. Qian Yi's 'Zhi Jue'("直訣") was influenced by 'Lu Xin Jing', yet if we compare the quality of 'Sheng Li, Byeng Li, Bang Jae'(生理, 病理, 方劑), 'Lu Xin Jing' cannot be the foundation of 'Zhi Jue'. He took over 'Nei Jing, Shang Han Lun, Jin Gui Yao Lue, Shen Long Ben Cao Jing, Tai Ping Sheng Hui Fang'("內經", "傷寒論", "金?要略", "神膿本草經", "太平聖惠方") and put them together to the direct clinical experiences of pediatrics. 3. There is no reference regarding the difficulties of pediatric diagnosis and diseases in 'Huang Di Nei Jing'("黃帝內經") Before 'Bei Song'(北宋), regardless of the lack of data related to pediatric diseases, 'Qian Yi' established the pediatric system in 'Xiao Er Yao Zheng Zhi Jue' for the first time. 4. In his diagnosis of the pediatric diseases, he 'Si Zhen He Can'(四診合參), also considered in the eye exam seriously. In addition, he closely combined 'Wu Zang Bian Zheng'(五臟辨證), and diagnosis the pediatric diseases. 5. 'Wu Zang Bian Zheng', what Qian established method was based on 'Zheng Ti Guan'(整體觀) in 'Huang Di Nei Jing'. It was based on clinical experiences and established the perspectives of 'Tian Ren Xiang Ying'(天人相應). First of all, he pinpointed 'Zhu Zheng'(主證) clearly. Secondly, he pinpointed the relationships to symptoms and then, he distinguished a generic character of 'Xu, Shi, Han, Re'(虛, 實, 寒, 熱). Finally, he made an induction from genealogical pediatric physiology. 6. 'Qian Yi' took a serious view of 'Ban Zhen'(斑疹), the inadequate field in those days. At that time, he criticized on the habituation of the misuse of medication. He treated separately which 'Ji Jing'(急驚) as 'Liang Xie'(凉瀉) and 'Man Jing'(慢驚) as 'Wen Bu'(溫補). He proposed 'Cong Gan Zhu Feng, Xin Zhu Jing'(從肝主風, 心主驚) theory and formulated 'Jing Feng'(驚風) theory as well. 7. As an opponent of a tendency to misusage of medicine, 'Qian Yi' made out a prescription with pliant medicine. He emphasized on the treatment to 'Gong Bu Shang Zheng, Bu Bu Zhi Xie, Xiao Bu Jian Shi'(攻不傷正, 補不滯邪, 消補兼施) because he had so lucid demonstration to 'Xu Shi Han Re'(虛實寒熱) of the five viscera in the field of 'Bang Yak'(方藥). 8. There were no pediatrics schools at that time, however, the pediatrics was being made up gradually by 'Jin Yuan Si Da Jia'(金元四大家) who was influenced by 'Qian Yi'. He raised an objection to medical treatment using pliant medicine. 'Qian Yi' applied 'Qu Xia'(驅下) treatment using 'Han Liang'(寒凉) medicine. 'Han Liang Pai'(寒凉派) is greatly influenced by Qian. 'Chen Wen Zhong'(陳文中) had a great impact on 'Han Liang Pai' who used a 'Zao Shu Wen Bu'(燥熟溫補) medicine for treatment. Since 'Song Jin'(宋金), he had a tremendous influence on pediatrics treating patients in both 'Han Wen'(寒溫) ways. 9. 'Qian Yi' had an influence on his medical thoughts on future generations, especially to 'Wan Quan'(萬全) of 'Ming Dai', 'Wu Tang'(吳塘) of 'Qing Dai'(淸代) and 'Yun Shu Jie'(?樹珏) of 'Min Guo'(民國). 'Wan Quan' is an advocate of 'You Yu, Bu Zu Zhi Shuo'(有餘, 不足之說)of 'Xiao Er Wu Zang'(小兒五臟) that he revealed Qian's 'Wu Zang Bian Zheng'(五臟辨證). 'Wu Tang' disclosed Qian's 'Xiao Er Ti Zhi Shuo'(小兒體質說) and 'Xiao Er Ke'(小兒科)'s 'Yong Yao Lun'(用藥論), therefore, he uncovered pediatric physiological characteristics through the advocate of Qian's 'Zang Fu Rou Ruo, Ji Gu Nen Qie, Yi Xu Yi Shi, Yi Han Yi Re' (臟腑柔弱, 肌骨嫩怯, 易虛易實, 易寒易熱). 'Yun Shu Jie' developed intrinsic relationships among time, symptom and 'Tian Ren Xiang Ying Guan'(天人相應觀), What 'Qian Yi' stated about them. And also, he developed Qian's 'Di Huang Wan'(地黃丸), 'Xie Qing Wan'(瀉靑丸), 'Yi Huang San'(益黃散) clinical usages as well. 10. Regarding Qian's 'Wu Zang Xu Shi'(五臟虛實), it has an influence on 'Zhang Yuan Su'(張元素)'s 'Zang Fu Bing Ji Bian Zheng'(臟腑病機辨證). 'Di Huang Wan', 'Xie Qing Wan', 'Xie Xin Tang'(瀉心湯), 'Yi Huang San', 'Xie Huang San'(瀉黃散) are the standard prescription of 'Wu Zang Bu Xie'(五臟補瀉). It is under the influence of Qian's treatment. Besides, 'Qian Yi' took a serious view of 'Xiao Er'(小兒)'s 'Pi Wei'(脾胃). 'Qian Yi' had an impact on 'Li Dong Yuan'(李東垣) one of the member of 'Bu Tu Pai'(補土派). 'Di Huang Wan', which placed great importance on 'Bu Yi Shen Yin'(補益腎陰), had a great impact on 'Da Bu Yin Wan'(大補陰丸) and 'Jin Yuan Si Da Jia' as well. 11. In a theory of Qian's 'Wu Zang Bian Zheng', though it had been stated clearly in 'Wu Zang Bian Zheng', but he neglected in 'Liu Fu Bian Zheng'(六腑辨證). In prescription field, The problem with the medicine is that it is either toxic or mineral, therefore, we are not able to use those medicine in a clinical testing at the present time.

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The Situation and the Tasks of UK Rail Privatization, Focusing on after the Hatfield Accident (영국 철도 민영화의 현황 및 과제 (Hatfield사고 이후의 변화를 중심으로))

  • Lee, Yong-Sang
    • Journal of Korean Society of Transportation
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    • v.24 no.2 s.88
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    • pp.91-100
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    • 2006
  • This paper examines the situation and tasks of UK rail privatization, especially focusing on after the Hatfield rail accident. Earlier research which focused on the UK's Privatization had little knowledge of the explanations for recent changes. Moreover they had difficulty making a direct comparison between national rail and the privatized rail. Therefore we aye left without a good explanation which has a comprehensive perspective. I attempt to show the change in the rail privatization Process and its outcome, focusing on after the Hatfield rail accident. This Paper argues that the UK's vail privatization process has a regulatory framework which is too complicated with overlapping responsibilities that brought about inefficiency, increasing costs and a superficial safety regime. Especially the planning of rail and infrastructure maintenance did not come to play an appropriate role. However after 2000, the government took charge of setting the strategy for railways, and the Office of Rail Regulation covered safety performance and cost. explain that these changes present a good opportunity to solve the problem of passing the buck for poor performance. Through the analysis, I find that the passenger rail network is well-suited to deliver long distance business and commuters and that the subsidy from the government is decreasing. However, performance, for example punctuality and reliability. should be improved. Especially the Hatfield rail accident caused a reduction in the satisfaction of passengers. In future. the problems of rising costs and monopoly franchise system should be addressed.

Effect of Seedling Age on Growth and Yield at Transplanting of Sorghum (Sorghum bicolor L. Moench) (수수 묘의 이식 시기가 생육 및 수량에 미치는 영향)

  • Jo, Su-Min;Jung, Ki-Youl;Kang, Hang-Won;Choi, Young-Dae;Lee, Jae-Saeng;Jeon, Seung-Ho
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.61 no.1
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    • pp.50-56
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    • 2016
  • Direct seeding of sorghum (Sorghum bicolor L. Moench) has a problem of low yield including poor establishment. This poor establishment results from poor quality seed, poor seedbed preparation, seedling pests, poor sowing technique and high soil temperature. This study sought to establish the age at which sorghum seedlings can be transplanted with minimal effects on grain yield. Transplants were raised in 128 nursery tray pot. Five seedling ages were established by transplanting at 10 (T10), 15 (T15), 20 (T20), 25 (T25) and 30 (T30) days after planting (DAP). The treatment combinations were arranged in a randomized complete block design and replicated three times with an individual plot size of $6{\times}5m^2$. Each plot had five ridges with a planting space of $0.60{\times}0.20m^2$ at one plants per stand. Results showed that seedling age on transplanting significantly affected growths and yields to sorghum after transplanting. Plant heights and diameters of transplants at T15 were longer than the other transplants. Conclusively, The advantages of this practice were better control of crop density and greater yields; either to fill gaps after emerging and thinning of crops or to compensate for a growth period that was too short for a complete crop cycle.

Development of An Instructional material for High School Environmental Education Emphasizing Affective Objectives (정의적 영역 중심의 고등학교 환경 교재 개발)

  • 박진희;장남기
    • Hwankyungkyoyuk
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    • v.6 no.1
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    • pp.63-99
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    • 1994
  • The international environmental activities and environmental education began in 1970's. Environmental education in Korea was emphasized since the Forth National Curriculum. 'The Environmental Education Curriculum' will be separated as one of the most important parts in the Sixth National Education Curriculum in Korea. The purpose of this study was development. of 'Environmental Science' of high school appropriate to Sixth National Education Curriculum. First step was to state goals of environmental education in detail based on analysis of goals about environmental education in our country and other countries. Second was to analyse seven environments-related texts of Korea, America and England. Third, to measure how much environmental education has achieved in Fifth National Curriculum of Korea. Fourth, to develop a new environmental text of high school level. Fifth, to verify the effect of developed environmental text. The environmental part of 'Science I'(unit V. Life and Environments) and high school environments-related reference text(Survival and Environments) in Korea, American knowledges. American 'Environments' was stressed in many skills but they didn't include various teaching strategies. On the other hand, American 'Science-Technology-Society(S-T-S)' and British 'Science and Technology in Society(SATIS)' were stressed in knowledges and skills, and they included many teaching strategies and student actions. American 'S-T-S' was the only one stressed in values and attitudes. And all seven texts were not interested in behaviors and participations. To measure the achievement of environmental education by questionnaire, 497 high school students in total were selected from five different schools. Actually, most students had a positive thinkings and attitudes in their hearts about environmental problems, about environmental problems, but many of them did not take actions to solve environmental problems and to protect environments. The higher the score students got in 'knowledges and informations', the higher the score in 'skill'. It implies that learning of skills is based on learning of knowledges and informations about environments. On the other hand, much knowledges and information about environments has not always ensured positive thinkings and attitudes or active behaviors and participations to solve environmental problem. In view that ultimate aim of environmental education is forming responsible environmental behaviors and the goals of values and behaviors are as important as knowledges and skills. A new environmental text of high school level was developed and it was based on analysis of seven texts and environmental education in Fifth Korean Curriculum. This text have seven units, 1. Habitates : What're the meanings?, 2. Nuclear Energy : Can't be Avoid?, 3. Acid Rain : What're the Messages?, 4. Ethanol : Is this Future Fuel?, 5. Wastes : A New War!, 6. What're the National and Gloval Environmental education and avoided from the array of knowledges. Therefore included various teaching strategies and independent actions of students. 'Open-ended value learning' and 'free behavior learning' in text were special learning parts for aquisition of values and formation of behaviors. To verify the effects. of new developed environmental text, the direct learning was carried out by 286 students in total. Post test scores of experimental groups per each units were significantly higher than those of control groups from five different schools were as follows. For validity of selecting contents for units, 74% of respondent replied positively. For classification and presentation of four goal-groups, 90% replied positively in validity and 82%, in utility. For validity of various teaching strategies, 88% and for the degree of including student-centered independent actions, 86% replied positively, For importances and expected effects of 'open=ended value learning' and 'free behavior learning', showed positive responses respectively, 88%, 92% Therefore this text is effective to achieve four goals of environmental education equally.

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Analysis of Patients with Dysesthesia after Mandibular Nerve Injury (하악신경 손상 후 발생한 감각부전 환자들에 대한 분석)

  • Choi, Young-Chan;Kwon, Jeong-Seung;Kim, Seong-Taek;Ahn, Hyung-Joon
    • Journal of Oral Medicine and Pain
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    • v.34 no.4
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    • pp.379-385
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    • 2009
  • The purpose of this study was to present basic data that is needed in comprehension of dysesthesia after mandibular nerve injury and grasp meaning. We analyzed medical records of 59 patients who were diagnosed as dysesthesia after mandibular nerve injury from January 2007 to July 2009. The results are summarized as follows. 1. The most frequent cause was implant surgery (59%) and the most frequent injured branch of mandibular nerve was inferior alveolar nerve(81%). 2. The period passed after nerve injury showed significant interrelationship with level of pain. Visual Analogue Scale(VAS) increased from 4.82 to 6.91 after 6 month. 3. The period passed after nerve injury did not show significant interrelationship with recovery of dysesthesia. But, when conservative treatment was offered at earlier stage, ratio of patients who showed recovery of symptom tended to increase. 4. In computed tomography, level of invasion into inferior alveolar nerve canal did not show significant interrelationship with level of pain and recovery of dysesthesia. Conclusively, in the patients with dysesthesia of mandibular nerve, inferior alveolar nerve injury by dental implant surgery dominated most significant problem. Although level of invasion into inferior alveolar nerve is the most important factor to initiation of dysesthesia, there are other various factors exert more influence on the level of pain or recovery of dysesthesia. Therefore, begining conservative therapy at earlier stage is encouraged. Also, because nerve injuries can occur without direct invasion into nerve canal, so leaving enough safe space from nerve canal is needed for prevention of indirect nerve injury.

Flexible Specialization: A New Paradigm for Modern Industrial Society ? (柔軟的 專門化(Flexible Specialization) : 현대 産業社會의 새로운 패러다임 ?)

  • Lee, Deog-An
    • Journal of the Korean Geographical Society
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    • v.28 no.2
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    • pp.148-162
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    • 1993
  • There is much speculation that modern capi-talist society is undergoing fundamental and qualitative chnge towards flexible specialization. The purpose of this study is to examine this hypothesis. This paper focusses on: the idea of flexible specialization; the significance of this transition; industrial district; and the implicati-ons of this new production system for Korean industrial space. Main arguments of this study are as follows: First, as all different groups of researchers apply the idea of flexible specialization according to their own specifications, the current debate on this topic is not much fruitful. Not surpri-singly, the concept of flexible specialization has overlapped with subocontracting. This intergration of subcontracting into flexible specialization systems, however, is inappropriate because the two concepts have different historical contexts. The other cause of this controversy is its inherent weekness, conceptual ambiguity. Thus, today's flexibility becomes tomorrow's rigidity. Secondly, transition towards flexible speciali-zation has only been partially achieved even in advanced capitalist countries. The application of dualistic explanatory framework, such as rigidity versus flexibiity, mass production versus small-lot multi-product production, and de-skilling versus re-skilling, has resulted in great exaggeration of the transformation, from Fordism to post-Fordism. There is no intermediary part between two places. Considering that the workers allocated to the Fordist mass production assembly line are not as large as one might imagine, the shift from mass to flexible production has only limited implications for the transformation of capitalist economy. Thirdly, 'industrial district' contorversy has contributed to highlighting the importance of small firms and areas as production space. The agglomeration of small firms in specific areas is common in Korea, but it is quite different from the industrial district based on flexible specialization. The Korean phenomenon stems from close interactions with its major parent firm rather than interactions between flexible, specialized, autonomous and technology-intensive smll firms. Most Korean subcontractors are still low-skilled, labour-intensive, and heavily dependent on their mojor parent firms. Thus, the assertion that the Seoul Metropolitan Area adopts flexible specialization has no base. Fourthly, the main concern of flexible speciali zation is small firms. However, the corporate organization that needs product diversification and technological specialization is oligopolistic large corporations typified by multinational corporations. It is because of this that most of these organizations are adoptiong Fordist mass production methods. The problem of product diversification will be resolved naturally if economic internationalization progresses further. What is more important for business success is the quality and price competitiveness of firms rather than product diversification. Lastly, in order to dispel further misunderst-anding on this issue, it is imparative that the conceptual ambiguity is resolved most urgently. This study recommends adoption of more speci-fied and direct terminology (such as, factory automation, computer design, out-sourcing, the exploitation of part-time labor, job redesign) rather than that of ideological ones (such as, Taylorism, Fordism, neo-Taylorism, neo-Fordism, post-fordism, flexible specialization, peripheral post-Fordism). As the debates on this topic just started, we still have long way to go until consensus is reached.

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Adhesion Characteristics and the High Pressure Resistance of Biofilm Bacteria in Seawater Reverse Osmosis Desalination Process (역삼투 해수담수화 공정 내 바이오필름 형성 미생물의 부착 및 고압내성 특성)

  • Jung, Ji-Yeon;Lee, Jin-Wook;Kim, Sung-Youn;Kim, In-S.
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.1
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    • pp.51-57
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    • 2009
  • Biofouling in seawater reverse osmosis (SWRO) desalination process causes many problems such as flux decline, biodegradation of membrane, increased cleaning time, and increased energy consumption and operational cost. Therefore biofouling is considered as the most critical problem in system operation. To control biofouling in early stage, detection of the most problematic bacteria causing biofouling is required. In this study, six model bacteria were chosen; Bacillus sp., Flavobacterium sp., Mycobacterium sp., Pseudomonas aeruginosa, Pseudomonas fluorescens, and Rhodobacter sp. based on report in the literature and phylogenetic analysis of seawater intake and fouled RO membrane. The adhesion to RO membrane, the high pressure resistance, and the hydrophobicity of the six model bacteria were examined to find out their fouling potential. Rhodobacter sp. and Mycobacterium sp. were found to attach very well to RO membrane surface compared to others used in this study. The test of hydrophobicity revealed that the bacteria which have high hydrophobicity or similar contact angle with RO membrane ($63^{\circ}$ of contact angle) easily attached to RO membrane surface. P. aeruginosa which is highly hydrophilic ($23.07^{\circ}$ of contact angle) showed the least adhesion characteristic among six model bacteria. After applying a pressure of 800 psi to the sample, Rhodobacter sp. was found to show the highest reduction rate; with 59-73% of the cells removed from the membrane under pressure. P. fluorescens on the other hand analyzed as the most pressure resistant bacteria among six model bacteria. The difference between reduction rates using direct counting and plate counting indicates that the viability of each model bacteria was affected significantly from the high pressure. Most cells subjected to high pressure were unable to form colonies even thought they maintained their structural integrity.