• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.345-359
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• 2006

Loss of maxillary molar teeth leads to rapid loss of crestal bone and inferior expansion of the maxillary sinus floor (secondary pneumatization). Rehabilitation of the site with osseointegrated dental implants often represents a clinical challenge because of the insufficient bone volume resulted from this phenomenon. Boyne & James proposed the classic procedure for maxillary sinus floor elevation entails preparation of a trap door including the Schneiderian membrane in the lateral sinus wall. Summers proposed another non-invasive method using a set of osteotome and the osteotome sinus floor elevation (OSFE) was proposed for implant sites with at least 5-6mm of bone between the alveolar crest and the maxillary sinus floor. The change of grafted material in maxillary sinus is important for implant survival and the evaluation of graft height after maxillary sinus floor elevation is composed of histologic evaluation and radiomorphometric evaluation. The aim of the present study was radiographically evaluate the graft height change after maxillary sinus floor elevation and the influence of the graft material type in height change and the bone remodeling of grafts in sinus. A total of 59 patients (28 in lateral approach and 31 in crestal approach) who underwent maxillary sinus floor elevation composed of lateral approach and crestal approach were radiographically followed for up to about 48 months. Change in sinusgraft height were calculated with respect to implant length (IL) and grafted sinus height(BL). It was evaluated the change of the graft height according to time, the influence of the approach technique (staged approach and simultaneous approach) in lateral approach to change of the graft height, and the influence of the type of graft materials to change of the graft height. Patients were divided into three class based on the height of the grafted sinus floor relative to the implant apex and evaluated the proportion change of that class (Class I, in which the grafted sinus floor was above the implant apex; Class II, in which the implant apex was level with the grafted sinus floor; and Class III, in which the grafted sinus floor was below the implant apex). And it was evaluated th bone remodeling in sinus during 12 months using SGRl(by $Br\ddot{a}gger$ et al). The result was like that; Sinus graft height decreased significantly in both lateral approach and crestal approach in first 12 months (p$MBCP^{TM}$ had minimum height loss. Class III and Class II was increased by time in both lateral and crestal approach and Class I was decreased by time. SGRI was increased statistically significantly from baseline to 3 months and 3 months(p<0.05) to 12 months(p$ICB^{(R)}$ single use, more reduction of sinusgraft height was appeared. Therefore we speculated that the mixture of graft materials is preferable as a reduction of graft materials. Increasing of the SGRI as time goes by explains the stability of implant, but additional histologic or computed tomographic study will be needed for accurate conclusion. From the radiographic evaluation, we come to know that placement of dental implant with sinus floor elevation is an effective procedure in atrophic maxillary reconstruction.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.168-176
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• 2011

Purpose: This study aims at investigating the influence of various insertion torques on thermal changes of bone. A proper insertion torque is derived based on the thermal analysis with two different implant designs. Materials and methods: For implant materials, bovine scapula bone of 15 - 20 mm thickness was cut into 35 mm by 40 - 50 mm pieces. Of these, the pieces having 2 - 3 mm thickness cortical bone were used as samples. Then, the half of the sample was immersed in a bath of $36.5^{\circ}C$ and the other half was exposed to ambient temperature of $25^{\circ}C$, so that the inner and surface temperatures reached $36.5^{\circ}C$ and $28^{\circ}C$, respectively. Two types of implants ($4.5{\times}10\;mm$ Br${\aa}$nemark type, $4.8{\times}10\;mm$ Microthread type) were inserted into bovine scapula bone and the temperature was measured by a thermocouple at 0.2 mm from the measuring point. Finite element method (FEM) was used to analyze the thermal changes at contacting surface assuming that the sample is a cube of $4\;cm{\times}4\;cm{\times}2\;cm$ and a layer up to 2 mm from the top is cortical bone and below is a cancellous bone. Boundary conditions were set on the basis of the shape of cavity after implants. SolidWorks was used as a CAD program with the help of Abaqus 6.9-1. Results: In the in-vitro experiment, the Microhead type implant gives a higher maximum temperature than that of the Br${\aa}$nemark type, which is attributed to high frictional heat that is associated with the implant shape. In both types, an Eriksson threshold was observed at torques of 50 Ncm (Br${\aa}$nemark) and 35 Ncm (Microthread type), respectively. Based on these findings, the Microthread type implant is more affected by insertion torques. Conclusion: This study demonstrate that a proper choice of insertion torque is important when using a specific type of implant. In particular, for the Microthread type implant, possible bone damage may be expected as a result of frictional heat, which compensates for initial high success rate of fixation. Therefore, the insertion torque should be adjusted for each implant design. Furthermore, the operation skills should be carefully chosen for each implant type and insertion torque.

• Journal of The Korean Association For Science Education
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• v.30 no.6
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• pp.693-718
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• 2010

This study investigated secondary school science teachers' experiences to explore the influencing factors in science teachers efficiency (STE). The participants, thirty three secondary school science teachers who have more than four years of teaching experience, were interviewed about describing each teacher's experience throughout one's years of teaching. The grounded theory introduced by Strauss and Corbin (1998) was used to analyze the data in this study. The results of paradigm analysis revealed that STE is influenced by 125 concepts, 38 sub-categories, and 16 categories. In a paradigm model, the central phenomenon was 'constructing STE', and the causal condition was 'want to be a teacher' as career choice motivation. The contextual conditions that have an affect on the central phenomenon were 'self awareness of the teacher' and 'social awareness of the teacher.' The mediate conditions, which facilitated or restrained the action/interaction strategies, were 'societal tendency', 'school climate', and 'personal context.' The action/interaction strategies to control the phenomenon were 'following the line,' 'identifying effective teaching strategies,' 'taking teacher education programs,' and 'contributing to school improvement.' The consequences were 'teacher's self awareness', 'challenge,' and 'stagnating in teaching.' The overall conclusion drawn from this research is that, the definition of STE is beliefs in science teachers' capabilities to set up objects in some school teaching context and, organize and execute the course of action required to attain these. Additionally, STE has three dimensions of teacher's behaviors: science instructional efficiency, efficiency in engaging students, and efficiency in managing school conditions. This study offers insight into the nature of STE and theoretical framework. These findings may give science teachers and teacher educators the practical knowledge necessary to build effective training programs and interventions that would help increase STE and facilitate effective teaching.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.538-543
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• 2008

Recently a nano-scale diamond is possible to manufacture forms of powder(below 100 nm) by new processing of explosion or deposition method. Using a sintering of nano-scale diamond is possible to manufacture of grinding tools. We have need of a processing development of coated uniformly inorganic to prevent an abnormal grain growth of nano-crystal and bonding obstacle caused by sintering process. This paper, in order to improve the sintering property of nano-scale diamond, we coated ZnO thin films(thickness: $20{\sim}30\;nm$) in a vacuum by ALD(atomic layer deposition) Economically, in order to deposit ZnO all over the surface of nano-scale diamond powder, we used a new modified fluidized bed processing replaced mechanical vibration effect or fluidized bed reactor which utilized diamond floating owing to pressure of pulse(or purge) processing after inserted diamond powders in quartz tube(L: 20 mm) then closed quartz tube by porosity glass filter. We deposited ZnO thin films by ALD in closed both sides of quartz tube by porosity glass filter by ALD(precursor: DEZn($C_4H_{10}Zn$), reaction gas: $H_2O$) at $10^{\circ}C$(in canister). Processing procedure and injection time of reaction materials set up DEZn pulse-0.1 sec, DEZn purge-20 sec, $H_2O$ pulse-0.1 sec, $H_2O$ purge-40 sec and we put in operation repetitive 100 cycles(1 cycle is 4 steps) We confirmed microstructure of diamond powder and diamond powder doped ZnO thin film by TEM(transmission electron microscope) Through TEM analysis, we confirmed that diamond powder diameter was some $70{\sim}120\;nm$ and shape was tetragonal, hexagonal, etc before ALD. We confirmed that diameter of diamond powders doped ZnO thin film was some $70{\sim}120\;nm$ and uniform ZnO(thickness: $20{\sim}30\;nm$) thin film was successfully deposited on diamond powder surface according to brightness difference between diamond powder and ZnO.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.219-226
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• 2014

Evaluation of tree responses to temperature elevation is critical for a development of forest management techniques coping with climate change. We conducted a study on the growth responses of Betula costata, Fraxinus rhynchophylla, and Quercus variabilis seedlings to open-field artificial warming. Artificial warming set-up using infra-red heater was built in 2012 and the temperature in warmed plots was regulated to be consistently $3^{\circ}C$ higher than that of control plots. The seeds of three species were sown, and the responses of growth, biomass allocation, and net photosynthetic rate of newly-germinated seedlings on the open-field artificial warming were determined. As a result, the growth responses of the seedlings differed with the species. B. costata showed decreases in the height to diameter ratio (H/D ratio), biomass, root weight to shoot weight ratio, and net photosynthetic rate. However, root collar diameter (RCD), height, biomass, and net photosynthetic rate of Q. variabilis were increased, while the response of F. rhynchophylla was rather obscure. There was no significant difference between warmed and control plots in seedling growth for 3 species in July, whereas, RCD, height, and H/D ratio of Q. variabilis were increased and H/D ratio of B. costata was decreased in November under warming. Species-specific growth responses to warming were similar to the species-specific responses of net photosynthetic rate and biomass allocation; therefore, net photosynthetic rate and biomass allocation might attribute to growth responses to warming. Besides, a relatively obvious response in autumn compared to summer might be affected by the phenological change following artificial warming. Species-specific responses of three deciduous species to warming in this study could be applied to the development of adaptive forest management policies to climate change.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.126-135
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• 2002

Plate bonding technique has been widely used in strengthening of existing concrete structures, although it has often a serious problem of premature falure such as interface separation and rip-off. However, this premature failure problem has not been well explored yet especially in view of local failure mechanism around the interface of plate ends. The purpose of the present study is, therefore, to identify the local failure of strengthened plates and to derive a separation criterion at the interface of plates. To this end, a comprehensive experimental program has been set up. The double lap pull-out tests considering pure shear force and half beam tests considering combined flexure-shear force were performed. The main experimental parameters include plate thickness, adhesive thickness, and plate end arrangement. The strains along the longitudinal direction of steel plates have been measured and the shear stress were calculated from those measures strains. The effects of plate thickness, bonded length, and plate end treatment have been also clarified from the present test results. Nonlinear finite element analysis has been performed and compared with test results. The Interface properties are also modeled to present the separation failure behavior of strengthened members. The cracking patterns as well as maximum failure loads agree well with test data. The relation between maximum shear and normal stresses at the interface has been derived to propose a separation failure criterion of strengthened members. The present study allows more realistic analysis and design of externally strengthened flexural member with steel plates.

• The Korean Journal of Financial Management
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• v.27 no.1
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• pp.181-208
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• 2010

In July 2007, Korean government has passed "The Capital Market and Financial Investment Services Act" to further develop the capital markets and the Act was to become effective in February 2009. Using a large sample of Korean firms, we have examined (i) the effect of underwriting activities on the firm value (bond spread) comparing commercial bank and investment bank, and (ii) the determinants of the firm value changes following underwriting activities of bank. To test our goal, we collected a wide range of samples of data for bond issuing activities executed by Korean firms listed on the Korea Stock Exchange (KSE) between 2000 and 2003. Our paper is distinguished from previous studies on this subject in a way that we analyzed the effect of corporate bond underwriting activities with regard to commercial banking and investment banking. Initially, we set up a hypothesis that "Certification View" and "Conflict-of-interest View" are major driving forces behind cross-firm differences in performance following bond issuance. We find that, in general, underwriting by investment bank (securities company) brings a positive effect on the firm value (spread between bench mark rate and bond issuing rate). This result indicates that firm value has been negatively affected by the bank underwriting and provides the evidence for "Conflict-of-interest View" in Korea. Our studies have also revealed that any change in firm value following bond issuance is positively related with the firm size (total asset), operating performance, liquidity (cashflow), and equity ownership by foreign investors. Overall, our results support the view that bank underwriting activities can play an important role in determining firm value and financial strategies under "The Capital Market and Financial Investment Services Act" of 2007.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.11
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• pp.1658-1672
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• 2016

This study aimed to investigate preferences for sous-vide cooked jabchae between Korean and Chinese consumers according to sauce mixing proportion. To commercialize sous-vide cooked jabchae and localize it for overseas circumstances in the Korean and Chinese markets, consumers' subjective preferences for sous-vide cooked jabchae were investigated especially in 119 Korean consumers (55 males and 64 females) and 136 Chinese consumers (70 males and 66 females). For jabchae samples, this study set up three different mixture rates of soy sauce and sugar, 8% (LSS), 13% (MSS), and 18% (HSS), and three different salad oil rates, 0% (LO), 12% (MO), and 24% (HO), to propose nine kinds of samples. As a result of consumer preferences, for Koreans, MSS and HSS regardless of oil content were significantly high in overall, appearance, saltiness, sweetness preferences, and purchase intention (P<0.001). In addition, for oiliness preference, LSS, MSS, LO, and MO were significantly high (P<0.001). For Chinese, HSS, MO, and HO were significantly high in overall, flavor preference, and purchase intention (P<0.001). For saltiness and sweetness preference, regardless of oil content, saltiness preference was significantly high in HSS and sweetness in MSS and HSS (P<0.001). For oiliness preference, regardless of content of soy sauce and sugar mixture, LO and MO were significantly higher, and for appearance preference, there was no significant difference among all samples (P<0.01). In general, both Korean and Chinese tended to prefer MS and HO, irrespective of oil content. Especially for Koreans, LSS was the least favorite sample in almost all preference questionnaires. For Chinese, preference scores for LSS and HSS were higher than for Koreans. On the other hand, oil content did not have much effect on consumer preference as compared with contents of soy sauce and sugar mixture.

• The Korean Journal of Air & Space Law and Policy
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• v.21 no.1
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• pp.135-167
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• 2006

Air service agreements between EU Member States and third countries concluded by Sweden, Finland, Belgium, Luxembourg, Austria, the Netherlands, Denmark and the United Kingdom after the Second World War infringe EU law. They authorize the third countries to withdraw, suspend or limit the traffic rights of air carriers designated by the signatory States. According to the Court of Justice of the European Communities (CJEC), these agreements infringe EU law in two respects. On the one hand, the presence of nationality clauses infringes the right of European airlines to non-discriminatory market access to routes between all Member States and third countries. On the other hand, only the EU has the authority to sign up to this type of commitment where agreements affect the exercise of EU competence, i.e. involve an area covered by EU legislation. The Court held that since the third countries have the right to refuse a carrier, these agreements therefore constitute an obstacle to the freedom of establishment and freedom to provide services, as the opening of European skies to third countries' companies is not reciprocal for all EU airlines. In the conclusion, in order to reconstruct these public international air law, The new negotiations between EU member states and third countries, especially the US, must be designed to ensure an adequate set of principles, so that Member States, in their bilateral relations with third countries in the area of air service, should consider following three models. The 1st, to develop a new model of public international air law such as a new Bermuda III. The 2nd, to reconstruct new freedoms of the air, for example, the 7th, 8th, and 9th freedoms. The 3rd, to explore new approaching models, such as complex system theory explored in the recent social sciences, to make access world-wide global problems instead of bilateral problems between EU member states and United States. The example will show any lessons to air talks between European Union and ROK.

• The Korean Journal of Air & Space Law and Policy
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• v.29 no.1
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• pp.161-198
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• 2014

The idea of creating an International Space Exploitation Agency (tentative title: hereinafter referred to ISEA) is only my academic and theoretical opinion. It is necessary for us to establish ISEA as an international organization for the efficient and rapid exploitation of natural resources in the moon and other celestial bodies. The creation of ISEA as a new international organization is based on the Article 11, 5 and Article 18 of the 1979 Moon Agreement. In order to create it as a preliminary procedure, it needs to make the Draft for the Convention on the Establishment an ISEA among the space-faring countries. The main contents of this paper is composed of (1) introduction, (2) joint exploitation of the natural resources (Heliumn-3, etc.) in the moon and ISEA, (3) activities for the exploitation of moon and other celestial bodies by the space-faring powers, (4) legal problems and Solution for the exploitation and mining rights of the natural resources in the moon, mars and celestial bodies, (5) procedure of creating an ISEA, (6) the principal points that need to be included in the draft for the ISEA convention, (7) conclusion. The creation of an ISEA would lead to a strengthening of the cooperation among the States deemed essential by the global community towards joint undertakings in space and would act as a catalyst for the efforts on the exploitation of the natural resources moon, mars, Venus, Mercury and other celestial bodies and allow resources, technology, manpower and finances to be centrally managed in an independent fashion to the benefit of the space-faring countries. It is desirable and necessary for us to create ISEA in order to promote cooperation in the field of space policy, law, science technology and industry etc. among the space-faring countries. The creation of the ISEA will be promoted the international cooperation among the space-faring countries in exploration and exploitations of the natural resources in the moon, Mars, Venus, Mercury and other celestial bodies. Finally, it should be noted that the political drive will be necessary not only to set up the organization ISEA, but also study a subsequent measures. It is also necessary for us to create the ISEA in order to develop the space industry, to strengthen friendly relations and to promote research cooperation among the space-faring countries based on the new ideology and creative ideas. If the heads (president or prime minister) of the space super-powers including the UNCOPUOS will be agreed to establish ISEA at a summit conference, 1 believe that it is possible to establish an ISEA in the near future.