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李奎燦 空軍士官學校 1982 論文集 Vol.14 No.-
Satellites can be used for communication, weather forecasting, education, and remote sensing of the resources of Earth. The emergence of this new type of human activity has brought about an urgent pressure for the introduction of a new branch of law. The purpose of this article is to consider the legal aspects of the utilization of satellites and to support the conclusion of the international conventions. Theses legal issues will be treated here under the following headings : (1) Questions relating to the use of Frequency Spectrum and of Geostationary Orbit; (2) Questions relating to Broadcasting Satellites; (3) Questions relating to Earth Exploration Satellites; (4) Questions relating to meteorological Satellites; and (5) Questions relating to navigation Satellites. The use of satellites for direct broadcasts, earth exploration, weather prediction control and navigation control may speed up immesurably the progress of education and cultural exchanges and lead to social and economic development of the entire world community. The successful utilization of satellites is to a large extent dependent on the degree and measure of cooperation between the members of the international community. Such a cooperation should be conducted on a basis of equality and mutual respect for the interest of all nations. The conclusion of special agreement is indeed an effective means of cooperation, provided that the concerned agreements are concluded on the basis of cooperation, provided that the concerned agreements are concluded on the basis of equality and do not establish a monopoly for one or a number of states conducting space activities. For, any kind of monopoly or special privileges for one or a number of states in outer space deprives other states of their rights to explore and use outer space on a basis of equality and without any discrimination.
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USEFULNESS OF SIMPLE SHIELDING TECHNIQUE USING MULTILEAF COLLIMATOR IN BREAST RADIATION THERAPY
이규찬,이석호,이성현,성기훈,안소현,최진호,동갑상,김효진,전용선,박흥규 대한방사선방어학회 2014 방사선방어학회지 Vol.39 No.4
This study was designed to assess whether the conventional tangential technique, using a multileaf collimator(MLC), allows a reduced dose to the organs at risk (OAR) in breast radiation therapy. A total of forty right andleft 20 for each breast cancer patients that underwent radiation therapy after breast conserving surgery were includedin this study. For each patient, the planning target volume (PTV) and OAR (heart, left anterior descendingartery (LAD), liver and lung) were defined and dose distribution were produced for conventional tangential beamsusing 6 MV photons. The treatment plans were made using the following two techniques for all patients. For thefirst plan (P1), MLC was designed to shield as much of OAR as possible without compromising the coverage ofPTV. In the second plan (P2), the treatment plan was created without using MLC. Dose-volume histograms forOARs were calculated for all plans. For left breast cancer, the percentage of maximum dose (Dmax%) and meandose (Dmean%) of OARs (heart and LAD) were calculated, and for right breast cancer, the percentage of the meandose (Dmean%) of the liver was calculated. The Dmean% of the lung was calculated in all patients. The mean values of Dmax% of the heart (86.9±19.5% range, 35.1-100.6%) in P1 were significantly lower than inP2 (98.3±3.4% range, 91.7-105.2%) (p=0.001). The mean values of Dmax% of LAD (78.4±22.5% range, 26.5-99.7%) inP1 was significantly lower than in P2 (93.3±8.1% range, 67.9-102.1%) (p<0.001). In P1, the mean values ofDmean% of the liver (4.8±2.0%) were significantly lower than in P2 (6.2±2.5%) (p<0.001). The mean values ofDmean% of the lung were significantly lower in P1 (9.3±2.3%) than in P2 (9.7±2.4%) (p<0.001). P1, by using MLC,allows a significantly reduced dose to OAR compared with P2. We can suggest that it is reasonable to routinelyuse MLC in the conventional tangential technique for breast radiation therapy considering the primary tumorlocation.
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방사선 조사가 백서 악하선 줄무늬관세포에 미치는 영향에 관한 투과전자현미경적 연구
이규찬,이상래,Lee Gyu-Chan,Lee Sang-Rae 대한영상치의학회 1990 Imaging Science in Dentistry Vol.20 No.2
The purpose of this study was to investigate the effects of irradiation on the striated duct cells of the rat submandibular gland ductal tissues which control the characteristics of saliva. For this study, the experimental group was composed of 36 irradiated Sprague Dawley strain rats divided into 8 subgroups 1 hour, 2 hours, 3 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours after irradiation. 4 non-irradiated rats were used as the control group. The experimental animals were singly irradiated with a dose of 18Gy gamma ray to their head and neck region by the Co-6- teletherapy unit and sacrificed after each experimental duration. The specimens were examined with a light microscope with an H-E stain and with a trans- mission electron microscope. The results of this study were as follows. In the light micrograph, a severe atrophic change occurred in the striated duct cells at 2hours after irradiation and gradual recovery occurred from 6 hours after irradiation. 2. The nuclear chromosomes of the striated duct cells were changed granular at 2 hours after irradiation. Recovery was observed at 6 hours after irradiation. Nuclear bodies were also observed from 3 hours after irradiation. 3. The mitochondria of the striated duct cells had indistinct cristae at 2 hours after irradiation, and were degenerated or swollen at 3 hours after irradiation. They recovered, however, from 6 hours, with an increasing number at 48 hours and a regular arrangement was observed at 72 hours after irradiation. 4. The microvilli showed atrophic changes at 2 hours after irradiation and were almost lost at 3 hours after irradiation. They were observed again from 48 hours after irradiation. 5. The rough endoplasmic reticulum and golgi body were not apparent at 1 hour after irradiation and were dilated with degeneration 2 hours after, but intact rough endoplasmic reticulum were observed from 3 hours after irradiation and developed well at 24 hours after irradiation. By the result of this study, showing a mild change in the functional morphology of the salivary striated duct cells immediately following irradiation, it is considered that the many complications which occur after radiation therapy, will disappear in time with the histological and the functional recovery of the glandular tissues.
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Cecal microbiome divergence of broiler chickens by sex and body weight
이규찬,길동용,설우준 한국미생물학회 2017 The journal of microbiology Vol.55 No.12
The divergence of gut bacterial community on broiler chickens has been reported as potentially possible keys to enhancing nutrient absorption, immune systems, and increasing poultry health and performance. Thus, we compared cecal bacterial communities and functional predictions by sex and body weight regarding the association between cecal microbiota and chicken growth performance. In this study, a total of 12 male and 12 female 1-day-old broiler chickens were raised for 35 days in 2 separate cages. Chickens were divided into 3 subgroups depending on body weight (low, medium, and high) by each sex. We compared chicken cecal microbiota compositions and its predictive functions by sex and body weight difference. We found that bacterial 16S rRNA genes were classified as 3 major phyla (Bacteroidetes, Firmicutes, and Proteobacteria), accounting for > 98% of the total bacterial community. The profiling of different bacterial taxa and predictive metagenome functions derived from 16S rRNA genes were performed over chicken sex and bodyweight. Male chickens were related to the enrichment of Bacteroides while female chickens were to the enrichment of Clostridium and Shigella. Male chickens with high body weight were associated with the enrichment of Faecalibacterium and Shuttleworthia. Carbohydrate and lipid metabolisms were suggested as candidate functions for weight gain in the males. This suggests that the variation of cecal bacterial communities and their functions by sex and body weight may be associated with the differences in the growth potentials of broiler chickens.
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사중극 질량 분석기의 이온소스 오염이 이온전류에 미치는 영향
이규찬,박창준,김진태,오은순,홍기성,홍승수,임인태,윤주영,강상우,신용현,Lee, K.C.,Park, C.J.,Kim, J.T.,Oh, E.S.,Hong, K.S.,Hong, S.S.,Lim, I.T.,Yun, J.Y.,Kang, S.W.,Shin, Y.H. 한국진공학회 2009 Applied Science and Convergence Technology Vol.18 No.3
The long term stability of ion current of QMS has been one of key parameters for monitoring gas process in vacuum. The time dependence of ionic current was monitored while the pressure of nitrogen gas was kept at a fixed pressure by introducing the gas into vacuum chamber. The chamber was evacuated to ${\sim}3{\times}10^{-9}\;Torr$ to reduce background signals before the measurement. Two ion sources were tested; one had brownish or black color due to gas contamination and the other one was new, i.e. cleaner. At a nitrogen pressure of $1{\times}10^{-5}\;Torr$, the ionic currents measured by the contaminated ion source decreased faster with time. The decrease rate was respectively ${\sim}46%$ for cleaner one and ${\sim}84%$ for contaminated one after ${\sim}5.5%$ hours. In order to test the effect of filament material on the ion current decrease, we fabricated a tungsten(W) filament which consisted of two parts; one half was made of W and the other was coated with yttria. The similar decrease of ionic currents were shown for the two types of filaments, indicating that slight change of temperature of filament due to material difference i.e. baking effect could not improve the origin of ionic current decrease. Overall the decreasing rate of ionic current is more closely associated with contaminated ion source of QMS rather than its filament materials. 사중극 질량분석기(Quadrupole Mass Spectrometer, QMS) 이온전류의 안정성은 진공공정 가스를 모니터링 하는데 중요한 요소 중 하나이다. 진공챔버에 질소가스를 주입하여 압력을 일정하게 유지하면서 시간에 따른 이온전류의 변화를 모니터링 하였다. 진공챔버는 측정하기 전에 잡음신호를 줄이기 위해 ${\sim}3{\times}10^{-9}\;Torr$ 까지 배기하였고, 두개의 이온소스를 측정했다; 하나는 오염된 것으로 갈색 또는 검은색을 띄고 있고 다른 하나는 새 것이다. 질소 압력 $1{\times}10^{-5}\;Torr$에서, 오염된 이온소스의 이온 전류는 시간이 지남에 따라 더 빨리 감소했다. 대략 5.5 시간이 지난 후, 감소율은 새 것이 ${\sim}46%$이고 오염된 것은 ${\sim}84%$였다. 필라멘트 재질이 이온 전류감소에 미치는 영향을 관찰하기 위해서 텅스텐 선의 반을 산화이트륨($Y_2O_3$)으로 코팅하여 필라멘트를 제작하였다. 유사한 이온전류 감소현상이 재질이 다른 두 필라멘트에서 나타났는데 이것은 필라멘트 재질에 의한 온도의 변화 즉 baking 효과로는 이온전류 감소의 원인을 개선할 수 없다는 것을 의미한다. 전반적으로 이온전류의 감소율은 필라멘트 재질보다 이온소스의 오염과 더 밀접하게 관계되어 있다.
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