• Journal of Periodontal and Implant Science
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• 제40권2호
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• pp.76-85
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• 2010

Purpose: This study aimed to evaluate the effectiveness of the modified sinus floor elevation technique described hereafter as a "hybrid technique," in 11 patients with severely resorbed posterior maxillae. Methods: Eleven patients who received 22 implants in the maxillary premolar and molar areas by the hybrid technique were enrolled in this study. A slot-shaped osteotomy for access was prepared on the lateral wall along the lower border of the sinus floor. The Schneiderian membrane was fully reflected through the lateral slot. Following drilling with the membrane protected by a periosteal elevator, the bone was grafted. All implants were placed simultaneously with sinus augmentation. The cumulative success rate was calculated and clinical parameters were recorded. Radiographic measurements were performed. Results: All implants were well maintained at last follow up (cumulative success rate=100%). The mean residual bone height, augmented bone height, crown-to-implant ratio, and marginal bone loss were $4.1{\pm}1.64mm$, $8.76{\pm}1.77mm$, $1.21{\pm}0.34mm$, and $0.34{\pm}0.72mm$, respectively. Conclusions: Simultaneous implant placement with sinus augmentation by hybrid technique showed successful clinical results over a 2-year observation period and may be a reliable modality for reconstruction of a severely resorbed posterior maxilla.

• The Korean Journal of Physiology and Pharmacology
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• 제5권1호
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• pp.1-8
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• 2001

Hyperpolarization of arterial smooth muscle by acetylcholine is considered to be produced by the release of an unidentified chemical substance, an endothelium-derived hyperpolarizing factor (EDHF). Several chemicals have been proposed as the candidate for EDHF. However, none of them fulfil completely the nature and property of EDHF. Ultrastructural observation with electron microscope reveals that in some arteries, gap junctions are formed between endothelial and smooth muscle cells. In small arterioles, injection of gap junction permeable dyes into an endothelial cell results in a distribution of the dye to surrounding cells including smooth muscle cells. These observations allow the speculation that myoendothelial gap junctions may have a functional significance. Simultaneous measurement of the electrical responses in both endothelial and smooth muscle cells using the double patch clamp method demonstrates that these two cell types are indeed electrically coupled, indicating that they behave as a functional syncytium. The EDHF-induced hyperpolarization is produced by an activation of $Ca^{2+}-sensitive\;K^+-channels$ that are inhibited by charybdotoxin and apamin. Agonists that release EDHF increase $[Ca^{2+}]_i$ in endothelial cells but not in smooth muscle cells. Inhibition of gap junctions with chemical agents abolishes the agonist-induced hyperpolarization in smooth muscle cells but not in endothelial cells. All these observations can be explained if EDHF is an electrotonic signal propagating from endothelium to smooth muscle cells through gap junctions.

• 한국레이저가공학회지
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• 제3권1호
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• pp.29-37
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• 2000

For a development purpose of thick metal / metal Graded-Boundary Materials(GBM), a basic research on the fabrication of Ni-Cr/steel GBM was carried out by a laser beam and its mechanical properties and thermal characteristics were investigated. In order to produce a compositionally graded boundary region between substrate steel and added Ni-Cr alloy, a series of surface alloying treatments was performed with a high power CO$_2$ laser beam. Ni-Cr sheet was placed on a low carbon steel plate(0.18%C), and then a CO$_2$ laser beam was irradiated on the surface to produce a homogeneous alloyed layer. On this first surface-alloyed layer, another Ni-Cr sheet was placed and then the CO$_2$ laser beam was irradiated again to produce second surface-alloyed layer. Sequential repetitions of laser surface alloying treatment 4 times resulted in a graded-boundary region with the thickness of about 1.4mm. Simultaneous concentration profiles of different kinds of alloying elements(Ni and Cr) showed from 42%Ni, 45%Cr and 13%Fe on surface region to 0%Ni, 0%Cr and 99%Fe in substrate region. Also a thermal conductivity gradient resulted in graded-region and its value changed from 0.03㎈/cm s$\^{C}$ in surface region to 0.1㎈/cm s$\^{C}$ in substrate region. Microstructural observation showed that any visible root porosities and solidification shrinkage cracks were not formed in graded region between alloyed layer and substrate region during rapid cooling.

• 대한원격탐사학회지
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• 제22권5호
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• pp.373-377
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• 2006

Seasonal threshold values for fog detection over the ten airport areas in the Korean Peninsula have been derived, using the satellite-observed data of polar-orbit (Aqua/Terra MODIS) and geostationary (GOES-9) during two years. The values are obtained from reflectance at $0.65{\mu}m\;(R_{0.65})$ and the difference in brightness temperature between $3.7{\mu}m\;and\;11{\mu}m\;(T_{3.7-11})$. In order to examine the discrepancy between the threshold values of two kinds of satellites, the following parameters have been analyzed under the condition of daytime/nighttime and fog/clear-sky, utilizing their simultaneous observations over the Seoul Metropolitan Area. The parameters are the brightness temperature at $3.7{\mu}m\;(T_{3.7})$, the temperature at $11{\mu}m\;(T_{11}$, and $T_{3.7-11}$ for day and night. The $R_{0.65}$ data are additionally included in the daytime. The GOES-9 thresholds over the seven airport areas except the Cheongju airport have revealed the accuracy of 50% in the daytime and 70% in the nighttime, based on statistical verification for the independent samples as follows; FAR, POD and CSI. However, the accuracy decreases in the foggy cases with twilight, precipitation, short persistence, or the higher cloud above fog.

• Journal of Astronomy and Space Sciences
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• 제38권4호
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• pp.203-215
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• 2021

The auroral observation has been started at Jang Bogo Station (JBS), Antarctica by using a visible All-sky camera (v-ASC) in 2018 to routinely monitor the aurora in association with the simultaneous observations of the ionosphere, thermosphere and magnetosphere at the station. In this article, the auroral observations are introduced with the analysis procedure to recognize the aurora from the v-ASC image data and to compute the auroral occurrences and the initial results on their spatial and temporal distributions are presented. The auroral occurrences are mostly confined to the northern horizon in the evening sector and extend to the zenith from the northwest to cover almost the entire sky disk over JBS at around 08 MLT (magnetic local time; 03 LT) and then retract to the northeast in the morning sector. At near the magnetic local noon, the occurrences are horizontally distributed in the northern sky disk, which shows the auroral occurrences in the cusp region. The results of the auroral occurrences indicate that JBS is located most of the time in the polar cap near the poleward boundary of the auroral oval in the nightside and approaches closer to the oval in the morning sector. At around 08 MLT (03 LT), JBS is located within the auroral oval and then moves away from it, finally being located in the cusp region at the magnetic local noon, which indicates that the location of JBS turns out to be ideal to investigate the variabilities of the poleward boundary of the auroral oval from long-term observations of the auroral occurrences. The future plan for the ground auroral observations near JBS is presented.

• Medical Lasers
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• 제10권2호
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• pp.96-105
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• 2021

Background and Objectives Skin aging is reportedly associated with regulation in collagen and elastin synthesis. This study investigated the potential of combining light-emitting diode (LED) treatments using a 630-nm and 850-nm LED with simultaneous microcurrent application. Materials and Methods The dorsal skin of female pigs was treated with a home-use device. We examined the treatment effects using photography, thermocamera, microscopic pathology, and histological examination to determine the mechanism of action, efficacy, and safety of the procedure. A histological observation was performed using hematoxylin and eosin, Masson's trichrome, Victoria blue, and immunohistochemical staining. We also used the Sircol soluble collagen and elastin assay kit to measure the amounts of collagen and elastin in the porcine back skin tissue after 2 and 6 weeks. Results Evaluation by visual inspection and devices showed no skin damage or heat-induced injury at the treatment site. Histological staining revealed that accurate treatment of the targeted dermis layer effectively enhanced collagen and elastin deposition. Collagen type I, a protein defined by immunohistochemical staining, was overexpressed in the early stages of weeks 2 and 6. Combined therapy findings showed the superior capability of the 630-nm and 850-nm LED procedures to induce collagen; in contrast, elastin induction was more pronounced after microcurrent treatments. Conclusion The home-use LED device, comprising a combination of 630-nm and 850-nm LEDs and microcurrent, is safe and can be used as an adjunctive treatment for self-administered facial rejuvenation.

• Journal of Korea Trade
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• 제25권1호
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• pp.65-88
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• 2021

Purpose - This paper aims to examine the determinants of SWFs' investment in Asian countries and to identify consistent investment patterns of SWFs in specific target firms from Asia, particularly China and South Korea. Design/methodology - This study extends the Tobin's Q model to examine the relationship between SWF investments in target firms and their returns with other firm-level control variables. We collect consistent data on SWF investments and the matched firm-level data on target firms, which of observation is 1,512 firms (333 in South Korea and 1,179 in China) targeted by 20 SWF sources during 1997-2017. The panel random effect model is used to estimate the extended Tobin's Q model. The robustness of the estimations is tested by the simultaneous equation models and the panel GEE model. Findings - The evidence shows that sovereign wealth funds are more inclined to invest in the financial sector with a monopoly position and in large firms with higher growth opportunity and superior cash asset ratios in China. In contrast to their investments in China, sovereign wealth funds in South Korea prefer to invest in strategic sectors, such as energy and information technology, and in large firms with high performance and low leverage. Sovereign wealth funds' investments tend to significantly improve the target firm's performance measured by sales growth and returns in both Korea and China. Originality/value - The existing literature focuses on examining the determination of SWFs investment in the developed countries, such as Europe and the United States. Our paper contributes to the literature in three ways; first, we analyzes case studies of SWF investments in Asian markets, which are less developed and riskier. Second, we examine whether the determination of SWF investment in Asian target firms depends on the different time periods, on types of sources of SWFs, and on acquiring countries. Third, our research uses vast sample data on target firms in longer time periods (1997-2017) than other previous studies on the SWFs for Asian markets.

• 천문학회보
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• 제46권1호
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• pp.45.1-45.1
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• 2021

The polarization degree as a function of phase angle (the Sun-target-observer's angle), so-called the polarimetric phase curves (PPC), have provided priceless information on asteroids' albedos since B. Lyot (1929). Succeeding experimental works in 1970s have confirmed the Umow law: There is a universal and strong correlation between the albedo and the PPC slope (slope of the tangential line at the zero of the PPC at phase angle ~ 20 degrees). Experiments in 1990s (ref [1]), on the other hand, have demonstrated that the negative branch of PPC is dependent on the size parameter (X ~ π * particle-size / wavelength), especially when X <~5. The change in particle size changed the minimum polarization degree, location of the minimum, and the width of the negative branch (called the inversion angle). From polarimetry[2] and spectroscopy[3], large asteroids are expected to be covered with fine (<~ 10 ㎛ size) particles due to the gravity. The size parameters are X ~ 30 at the optical wavelength (λ ~ 0.5 ㎛) and X ~ 10 in near-infrared (J, H, Ks bands; λ ~ 1.2-2.2 ㎛), if the representative particle size of 5 ㎛ is considered. Accordingly, the near-infrared polarimetry has a great potential to validate the idea in ref[1]. We conducted near-infrared photopolarimetry of the large asteroid (4) Vesta using the Nishiharima Infrared Camera (NIC) at Nishi-Harima Astronomical Observatory (NHAO). NIC allows simultaneous polarimetric measurements in J, H, and Ks bands, and thus the change of PPC is obtained for three different size parameters. As a result, we found a signature of the change in the negative branch in the PPC of asteroid (4) Vesta. We will introduce our observation and the results and give an interpretation of the regolith on Vesta.

• 대한한의학회지
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• 제16권2호
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• pp.17-35
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• 1995

연구배경(硏究背景) 및 목적(目的): 국내(國內) 대부분(大部分)의 한방병원(韓方病院)에서 많은 수의 환자(患者)가 중풍(中風)으로 입원(入院)하고 있다. 이에 한방병원(韓方病院)을 찾고 있는 중풍환자(中風患者)에 대한 임상적(臨床的) 통계분석(統計分析)과 더불어 앞으로 나아가야 할 방향(方向)등에 대해 많은 연구(硏究)가 필요(必要)할 것으로 여겨져 본 연구(硏究)를 시작(始作)하였다. 대상(對象) 및 방법(方法): 1994년 1월(月) 1일(日)부터 동년(同年) 12월(月) 31일(日) 까지 경원대학교(暻園大學校) 부속(附屬) 한방병원(韓方病院) 순환기내과(循環器內科)에 Brain CT나 MRI상(上) 뇌혈관질환(腦血管疾患)으로 진단(診斷)받거나, 임상적(臨床的) 증상(症狀)으로 뇌졸중(腦卒中)으로 진단(診斷)받은 161예(例)의 환자(患者)를 대상(對象)으로 조사(調査)하였다. 결과(結果) 및 결론(結論): 1. 뇌졸중(腦卒中)의 종류별(種類別) 빈도(頻度)에서 뇌경색(腦梗塞)이 가장 많았으며 뇌출혈(腦出血), 지주막하출혈(蜘蛛膜下出血), 고혈압성뇌증(高血壓性腦症), 일과성뇌허혈발작(一過性腦虛血發作)의 순(順)이었다. 2. 선행질환(先行疾患)은 고혈압(高血壓)이 가장 많았으며, 당뇨(糖尿)도 많은 예(例)에서 나타났다. 3. 일반적(一般的)인 통례(通例)와는 달리 겨울보다는 여름에 많이 발생(發生), 입원(入院)하였다. 4. 입원당시(入院當時) 의식상태(意識狀態)가 안 좋았던 환자(患者)에게서 예후불량(豫後不良)한 환자(患者)가 많이 나타났다. 5. 물리치료(物理治療)의 평균(平均) 개시시기(開始時期)는 뇌경색(腦梗塞)에서 11.4일(日), 뇌출혈(腦出血)에서 22.7일(日)이었다. 6. 한(韓), 양방(洋方) 협진(協診)을 실시(實施)한 경우가 많았으며, 그 필요성(必要性)이 많이 나타났다.진단(診斷)에서부터 치료(治療)의 전과정(全過程)을 통(通)해서 서의치료(西醫治療)와 동의치료(東醫治療)를 결합(結合)하여 종합치료(綜合治療)를 하므로써 폐암(肺癌)의 치료효과(治療效果)를 높일 수 있는 새로운 치료법(治療法)으로 계속적인 연구(硏究)가 필요(必要)할 것으로 사료(思料)된다.較)하였다. 끝으로 본(本) 연구는 1965 年度 서울대학교 대학원(大學院) 연구비(硏究費)로 수행(遂行)한 것이며 본 연구를 시종 지도편달(指導鞭撻) 해 주신 서울대학교 농과대학 농화학과 주임교수 이춘영박사(李春寧博士)에게 감사(感謝)를 드리며 또한 본 연구의 시료를 제공하여 주신 서울대학교 농과대학 농학과 이고웅박사(李股雄博士)에 게 사의(謝意)를 표하는 동시에 본 연구의 분석에 협력하여 준 서울대학교 대학원 농화학과 김수영군(金洙榮君)에게 사의(謝意)를 표하는 바이다. 5 참조(參照)) (4) 벼를 pot에 심고 2회(回)에 걸쳐 control, Imidan, N-hydroxy methyl phthalimide, anthranilic acid 및 phthalimide의 10, 25, 50, 100 ppm 농도(濃度)의 각(各) 유제(乳劑)를 살포하고 일정기간후(一定期間後) 생육상(生育相)을 조사(調査)하였더니 Imidan 구(區)와 N-hydroxy methyl phthalimide 구(區)가 control 보다 좋은 성적(成績)을 보였다. (5) Imidan 250 ppm 유제(乳劑)를 수도엽면(水稻葉面)에 살포(撒布)하고 3 일(日), 5 일(日), 7 일(日) 및 14일후(日後)에 일정량(一定量)의 엽경(葉莖)을 채취(採取)하여 acetone으로 추출(抽出)k고 acetonitrile을 가지고 prechromatographic piriication 을 거쳐 paper chromatography에 의(依)하여 다음과

• 대한한의학회지
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• 제18권1호
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• pp.5-24
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• 1997

연구배경(硏究背景) 및 목적(目的): 국내(國內) 대부분(大部分)의 한방병원(韓方病院)에서 많은 수의 환자(患者)가 중풍(中風)으로 입원(入院)하고 있다. 이에 한방병원(韓方病院)을 찾고 있는 중풍환자(中風患者)에 대한 임상적(臨床的) 통계분석(統計分析)과 94年(년) 본원(本院)의 임상통계논문(臨床統計論文)과의 비교(比較), 그리고 앞으로 나아가야 할 방향(方向)등에 대해 많은 연구(硏究)가 필요(必要)할 것으로 여겨져 본 고찰(考察)을 시작(始作)하였다. 대상(對象) 및 방법(方法): 1995년 1월(月) 1일(日)부터 동년(同年) 12월(月) 31일(日) 까지 경원대학교(景園大學校) 부속(附屬) 한방병원(韓方病院) 순환기내과(循環器內科)에 Brain CT, TCD나 MRI上 뇌혈관질환자(腦血管疾患)으로 진단(診斷)받거나, 임상적(臨床的) 증상(症狀)으로 뇌졸중(腦卒中)으로 진단(診斷)받은 226예(例)를 환자(患者)를 대상(對象)으로 조사(調査)하였다. 결과(結果) 및 결론(結論): 1. 뇌졸중(腦卒中)의 종류별(種類別) 빈도(頻度)에서 뇌경색(腦梗塞)이 가장 많았으며 뇌출혈(腦出血), 일과성뇌허혈발작(一過性腦虛血發作), 지주막하출혈(蜘蛛膜下出血)의 순(順)이었다. 2. 선행질환(先行疾患)은 고혈압(高血壓)이 가장 많았으며, 당뇨(糖尿)도 많은 예(例)에서 나타났다. 3. 일반적(一般的)인 통례(通例)와는 달리 겨울보다는 봄과 여름에 많이 발생(發生), 입원(入院)하였다. 4. 입원당시(入院當時) 인식상태(認識狀態)가 좋지 않았던 환자(患者)에게서 예후불량(豫後不良)한 환자(患者)가 많이 나타났다. 5. 한(韓), 양방(洋方) 협진(協診)을 실시(實施)한 경우가 많았으며, 그 필요성(必要性)이 많이 나타났다.