• New & Renewable Energy
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• v.8 no.2
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• pp.33-43
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• 2012

Why solar companies preferred vertical integration of whole value chain? Major solar companies have built internally strong vertical integration of entire PV value chain. We raise a question whether such integration increases the corporate value and whether market situation affects the result. To test these questions, we conducted multi-variant analysis where characteristic factors mainly affect the corporate value measured in terms of Tobin'Q, based on the financial and non-financial data of PV companies listed in US stock market between 2005 and 2010. We hypothesize that since integration increases the overall efficiency but decreases the flexibility to adjust to various market situation, the combined effect of the efficiency gain and the flexibility loss ultimately determines the sign of integration effect on the corporate vale. We infer that the combined effect will be influenced heavily by business cycle, as in boom market (Seller's market) the efficiency gain may be larger than the flexibility loss and vice versa in bust market. We test whether the sign of combined effect changes after the year of 2009 and which factors influence most the sign. Year of 2009 is known as the year when market shifted from Seller's to Buyer's market. We show that 1) integration increases corporate value in general but after 2009 integration significantly decreases the value, 2) the ratios such as Production/Total Cost, Cash turnover period chosen for reversal of the flexibility measure are negatively affect Tobin's Q and especially stronger after 2009. This shows the flexibility improves corporate value and stronger in the recess period (Buyer's market). These results imply that solar company should set up integration strategy considering the tradeoff between efficiency and flexibility and the impact of the business cycle on both factors. Strategy only based on the price competitiveness determined in boom time can bring undesirable outcomes to the company. In addition, Strategic alliances in some value chains as a flexible bondage should be taken in account as complementary choice to the rigid integration.

• Land and Housing Review
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• v.5 no.3
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• pp.151-167
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• 2014

Urban space structure in South Korea when through drastic changes ever since public housing policies began their full-fledge implementation. That is, public housing policies represent the main cause for formation of the current urban space structure, as the public houses are constructed in accordance with changes of demographic/social structure, considering changes of housing demand, in urban spaces demanded by the end users. After rapid industrialization and urbanization in the 1960's, each government in different periods have implemented housing supply policies through massive urban developments, to resolve the issue of housing shortage and residential instability. Phase 1 New Towns were developed in the 1980's resulting in suburbanization of the Seoul Area, followed by urban sprawl due to construction of small-size New Towns after deregulation in the 1990's, and construction of Phase 2 New Towns for resolution of housing shortage in the early 2000's and the resulting urban problems. In the mid-2000's, construction of Bogeumjari houses in GB areas led to insufficient housing supply in downtown areas, and the period after 2010 witnessed continuous deterioration of existing urban areas and acceleration of the rental housing crisis caused by rental housing shortage in downtown areas. Moreover, the residentially vulnerable classes consisting of young, 1~2-member households is expanding, with the real estate market in recess. Therefore, the government is trying to achieve urban regeneration through public housing policies so as to resolve the urban space problem and the housing problem at the same time, and the Happiness Housing Project has been implemented as a policy to achieve that goal. The Happiness Housing Project for young, residentially vulnerable classes in downtown areas, is going through diversification aimed at conjunction with urban regeneration projects in downtown areas, as exemplified by conversion of rental houses in residential environment improvement project districts and redevelopment/reconstruction project districts into happiness housing, and supply of happiness housing in conjunction with small reorganization projects for deteriorated residential areas in such areas as those excluded from New Town designation. Continuous supply of Happiness Housing in conjunction with urban regeneration requires mixed-use residential development which includes convenience facilities and public facilities, along with improvement of rental conditions (rental period/rent) and diversification of project methods, considering that the project is implemented in downtown areas.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.161-171
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• 2014

Recession of hydrograph gives a significant contribution to estimation of baseflow using rainfall-runoff models and baseflow separation methods, because recession affects baseflow. This study attempted to enhance the accuracy of streamflow predictions using a Soil and Water Assessment Tool (SWAT) model and to separate baseflow from the predicted streamflow. For this, this study used two scenarios: 1) to calibrate eleven parameters using an auto-calibration tool with the alpha factor obtained from RECESS (S1); and 2) to calibrate twelve SWAT parameters including alpha factor (one of SWAT parameters) using an auto-calibration tool (S2). Then, baseflow spearation from the predicted streamflow was conducted by using Web-based Hydrograph Analysis Tool (WHAT). The results show that there is no significant difference between Nash-Sutcliffe efficiency (NSE) values of S1 and S2 for calibrations to streamflow. However, calibrations to baseflow showed that NSEs are 0.777 for S1 and 0.844 for S2, which means a significant difference. Quantitatively compared to the observed streamflow, relative errors were 20.78 % for S1 and 6.59 % for S2. Finally, this study showed the importance of recession in baseflow separated from the predicted streamflow using a rainfall-runoff model.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.5
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• pp.504-510
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• 2007

Purpose: The purpose of this study was to determine the incidence of antral septa and the accuracy of panoramic radiograph in identifying maxillary sinus septa. In addition, when panoramic radiograph led to a false diagnosis of more than majority, we analyzed findings of the panoramic radiograph. Patients and methods: This study included 180 patients who were radiographically examined before the surgery was done using both panoramic and computerized tomographic radiographs(CT scan), Samsung Medical Center from April 2003 to March 2006, and examined the incidence of antral septa, the false diagnosis rate of panoramic radiograph, and radiographic characters in case of false diagnosis. Only those bone lamellae were considered as septa that showed a height of at least 3.0mm. It was thus possible to exclude the alveolar recess. One oral and maxillofacial surgeon(OMFS) determined the presence or absence of sinus septa in CT scan, and five OMFS determined the presence or absence of sinus septa in panoramic radiograph. Results: The septa were observed in 81 of 360 sinuses(22.5%). All septa were oriented in a buccopalatal plane. More or less greater prevalence was observed in the second molar region(38.2%) but no predominant location was found. Panoramic radiograph led to false diagnosed septa in 361 of 1800 cases(20.1%). In case of false diagnosis of more than majority, superimposed image on zygomatic process was 44.1%, faint image in the region not related to sinus lifting 26.5%, faint image in the region related to sinus lifting 17.6%, and misconception for superimposed image 11.8% Conclusion: In this study we could get clinico-anatomical information of septum in the maxillary sinus. Compared to CT scan, panoramic radiograph can not clearly differentiate the sinus septa, but we consider that panoramic radiograph may improve its usefulness if we take additional modified panoramic radiograph and clinical exam.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.83-92
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• 1968

A study was planned to evaluate the effects of removal of the cingulate cortex upon the occurrence of any behavior commonly displayed by the rat, and to compare the effects of cingulectomy with those of removal of the parietal, parieto-occipital, or occipital regions. The subjects were 54 male albino rats (Holtzman strain, body weight $200{\sim}330\;gm$) including 14 rats in which the cingulate gyri between splenium and genu of the corpus callosum were bilaterally ablated by suction (cingulate group), 9 animals which had their parietal cortices (chiefly area 7) partially removed (parietal group), 9 rats whose parietal and occipital regions (chiefly areae 7 & 17), 13 animals in which the occipital cortices (chiefly area 17) were removed bilaterally (occipital group), and 9 normal rats (normal control group). Eighteen observation cages, each of which housed a subject and was provided with food and water ad lib., were arranged in 6 rows on a rack and the behavior of each subject was scanned by an observer at a distance of 1.5 m from the rack. The observer scanned the first and second rows 6 times in 1 min, then proceeded to the 3rd and 4th rows, scanning for another 1 min, and finally to the 5th and 6th rows. The speed of scanning was such that behavioral observations of all of the 18 rats were completed in 3 min, each subject receiving 6 observations. The scanning was repeated every 3 min for 18 min, which constituted one observation session and was followed by a 72 minutes' recess. The whole procedure was repeated through 24 hours so that a total of 576 behavioral observations were made on each subject in 16 observation sessions. Behaviors checked were sleeping, lying, lying and sniffing, standing, standing and sniffing, exploring, eating, drinking, grooming (included were washing, licking, and scratching), and others. Results obtained were as follows: 1. The cingulate group ate significantly more often than the normal control, the parietal, and the parieto-occipital groups. 2. Exploration was significantly less frequent in the cingulate group than in the normal control, the parietal, and the occipital groups. There was, in the case of the cingulate group, a significant negative correlation between the occurrence of eating and the exploratory activity. 3. The general activity, as judged from the value obtained by adding the occurrence of exploration, eating, drinking, grooming, and standing and sniffing, was significantly increased in the cingulate group compared with those of any other groups including the normal control. 4. Though statistically insignificant, the cingulate group slept least often among all the animal groups tested. 5. The parieto-occipital group tended to groom less, and the parietal group to eat less often than the normal control group did, but the difference was not significant. There were no significant differences among all the groups except the cingulate group as regards other behaviors analyzed. Based on the above results, it was inferred that the cingulate cortex exerts an inhibitory influence upon the occurrence of eating and general activity, while it tends to facilitate the occurrence of sleep.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.406-406
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• 2010

일반적으로, 나노스케일의 MOS 소자에서는 게이트 절연체 두께가 감소함에 따라 tunneling effect의 증가로 인해 PID (plasma induced damage)로 인한 소자 특성 저하 현상을 감소하는 추세로 알려져 있다. 하지만 요즘 많이 사용되고 있는 high-k 게이트 절연체의 경우에는 오히려 더 많은 charge들이 trapping 되면서 PID가 오히려 더 심각해지는 현상이 나타나고 있다. 이러한 high-k 게이트 식각 시 현재는 주로 Hf-based wet etch나 dry etch가 사용되고 있지만 gate edge 영역에서 high-k 게이트 절연체의 undercut 현상이나 PID에 의한 소자특성 저하가 보고되고 있다. 본 연구에서는 이에 차세대 MOS 소자의 gate stack 구조중 issue화 되고 있는 metal gate 층과 gate dielectric 층의 식각공정에 각각 중성빔 식각과 중성빔 원자층 식각을 적용하여 전기적 손상 없이 원자레벨의 정확한 식각 조절을 해줄 수 있는 새로운 two step 식각 공정에 대한 연구를 진행하였다. 먼저 TiN metal gate 층의 식각을 위해 HBr과 $Cl_2$ 혼합가스를 사용한 중성빔 식각기술을 적용하여 100 eV 이하의 에너지 조건에서 하부층인 $HfO_2$와 거의 무한대의 식각 선택비를 얻었다. 하지만 100 eV 조건에서는 낮은 에너지에 의한 빔 스케터링으로 실제 패턴 식각시 etch foot이 발생되는 현상이 관찰되었으며, 이를 해결하기 위하여 먼저 높은 에너지로 식각을 진행하고 $HfO_2$와의 계면 근처에서 100 eV로 식각을 해주는 two step 방법을 사용하였다. 그 결과 anistropic 하고 하부층에 etch stop된 식각 형상을 관찰할 수 있었다. 다음으로 3.5nm의 매우 얇은 $HfO_2$ gate dielectric 층의 정확한 식각 깊이 조절을 위해 $BCl_3$와 Ar 가스를 이용한 중성빔 원자층 식각기술을 적용하여 $1.2\;{\AA}$/cycle의 단일막 식각 조건을 확립하고 약 30 cycle 공정시 3.5nm 두께의 $HfO_2$ 층이 완벽히 제거됨을 관찰할 수 있었다. 뿐만 아니라, vertical 한 식각 형상 및 향상된 표면 roughness를 transmission electron microscope(TEM)과 atomic force microscope (AFM)으로 관찰할 수 있었다. 이러한 중성빔 식각과 중성빔 원자층 식각기술이 결합된 새로운 gate recess 공정을 실제 MOSFET 소자에 적용하여 기존 식각 방법으로 제작된 소자 결과를 비교해 본 결과 gate leakage current가 약 one order 정도 개선되었음을 확인할 수 있었다.

• Journal of Rhinology
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• v.25 no.2
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• pp.75-79
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• 2018

Background and Objectives: To investigate the common site of recurrent epistaxis after initial intervention such as packing and cauterization had failed and to evaluate the efficacy of surgical endoscopic electrocautery. Subjects and Method: Retrospective review of 47 patients with recurrent and uncontrolled idiopathic epistaxis between October 1995 and March 2016. All patients underwent endoscopic examination in the operating room after hospitalization. We performed electrocautery when a bleeding site was found. Results: The most common sites of bleeding were the inferior meatus (28%), sphenoethmoid recess (23%), superior septum around the olfactory cleft (13%), and the posterior end of the middle turbinate (15%). There was no serious complication during the one week after surgery. In 46 (98%) patients, refractory epistaxis was successfully controlled. One patient had recurrent epistaxis after electrocautery and underwent endoscopic sphenopalatine artery ligation. Conclusion: In patients with refractory idiopathic epistaxis after failure of first-line treatment, endoscopic examination through a surgical approach and electrocautery for suspected bleeding are effective.

• Restorative Dentistry and Endodontics
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• v.33 no.1
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• pp.66-75
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• 2008

This study examined the influence of the apical sizes on the sealing ability of a root canal filling. Thirty-six single rooted teeth with a single canal were divided into 3 groups (n = 12) and instrumented with either the $Profile^{(R)}$ or $LightSpeed^{(R)}$ system to achieve three different apical sizes (master apical file [MAF] of #25, #40, or #60). The teeth were filled with gutta perch a using a modified continuous wave technique. The level of microleakage was determined by immersing ten teeth from each group into India ink for 1 week followed by clearing with nitric acid, ethyl-alcohol, and methylsalicylate. The microleakage was measured using vernier calipers. The data was analyzed statistically using Kruskal-Wallis one-way ANOVA and a Student-Newman-Keuls Method. Two teeth from each group were sectioned horizontally at 1, 2, 3 and 4 mm from the apex in order to observe a cross section. The apical size was significantly (p < .05) influenced the level of microleakage. In the Student-Newman-Deuls Method, MAF sizes of #25 and #40; and MAF sizes of #25 and #60, respectively showed a statistically significant difference. There was no significant difference between #40 and #60. In most cross sections, oval-shaped canals were observed, and the irregularity of the internal surface increased with decreasing apical size. There was also an increase in the area of recess, which is the area where the canal space is not filled with either gutta-percha or sealer. When the root canals are filled using a modified continuous wave technique, canal filling with more consistent and predictable outcome may be expected as the apical preparation size is increased.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.286-298
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• 1994

The object of this study was to examine the user's impacts on the environmental deteriorations of trail at Ticket Office - Paekryunsa (Temple) Hyangch$\hat{o}$kpong - Dongyupryung - Chilyun Fall area in T$\hat{o}$kyusan National Park. Four trails were sampled in the study area according to the amount of users. Then the user's impacts on trail were measured at each trail. The Ticket Office-Paekryunsa trail was the most used district and followed at Paekryunsa-Hyangch$\hat{o}$kpong trail, Hyangch$\hat{o}$kpong-Dongyupryung trail in descending order. Dongyupryung-Chilyun Fall trail is not used by people because of rest rotation system. The entire width of trail was greater at the more heavily used trail. Maximum depth, cross-sectional area loss, and surface texture and roughness of trail were the highest at Paekryunsa-Hyangch$\hat{o}$kpong trail. Soil hardness, soil acidity, soil moisture content, organic matter content, and exchange canon were influenced by trampling. Soil hardness, soil acidity and exchange canon increased in tramples soil, but content of soil moisture and organic matter decreased therein. Environmental deteriorations of trail were significantly influenced by the amount of users and the slope of trail. Bared lands about $2.000m^2$ were appeared by trampling and camping around Hyangch$\hat{o}$kpong. Effects of carrying of rest rotation system for National Park were partly recognized at Dongyupryung-Chilyun Fall trail.