THERRESTRIAL IMPACT CRATERING CHRONOLOGY: A PRELIMINARY ANALYSIS

Moon, Hong-Kyu,Mi, Byung-Hee,Fletcher, Andre-B.,Kim, Bong-Gyu The Korean Space Science Society 2001 Journal of Astronomy and Space Sciences Vol.18 No.3

We have recently compiled a database of the properties of 192 impact craters, which supercedes previous compilations. Using our database, the impact structures found in North America, Europe and Australia have been examined; these cratonic areas have been relatively stable for considerably long geological periods, and thus have been best preserved. It is confirmed that there is a close correlation between the geological epoch boundaries, the epochs of mass extinctions, antral the "timing" of impacts. In addition, the terrestrial cumulative flux of objects >20km is found to be $1.77{\times}10^{-15}km^{-2}yr^{-1}$, over the last 120 Myr, which is much smaller than the published values in McEwen et al. (1997) and Shoemaker (1998) ($5.6{\pm}2.8{\times}10^{-15}km^{-2}yr^{-1}$. For terrestrial impact structures with D> 50 km, the apparent cumulative flux over the last 2450 Myr is ~50 times smaller than the corresponding value for the Moon. If we assume that the Earth and the Moon suffered the same level of bombardment over this time, this would mean that the actual flux of impacting bodies, capable of making craters with D)50 km, was ~ 50 times larger than the apparent flux estimated from the currently known terrestrial records.

제주 차귀도 연안해역 미생물 분포 및 이화학적 특성

문영건,김만철,이준백,송춘복,여인규,김종만,박근태,손홍주,최우봉,허문수 한국환경과학회 2006 한국환경과학회지 Vol.15 No.3

생선 가시로 인한 소장 천공 및 복강내 농양 1예

문성수,이수형,이은아,박성한,이준식,홍현진,신은경,김규종 고신대학교의과대학 2007 고신대학교 의과대학 학술지 Vol.22 No.1

A variety of swallowed foreign bodies are seen in gastrointestinal tract. However 80-90% of objects usually pass spontaneously through the alimentary tract and out in the feces and 10-20% removed without complication endoscopically. Therefore about less than 1% of foreign bodies ingested only require surgery due to complications, such as perforation, obstruction. Perforation of the gastrointestinal tract is a well-recognized complication of the foreign body ingestion. The most common site is ileum. Unfortunately, the diagnosis of small-bowel perforation by foreign bodies is rarely made preoperatively because the clinical symptoms are usually nonspecific or mimic other surgical conditions, such as appendicitis, diverticulitis, and perforated peptic ulcer etc. We report here a rare case of the small bowel perforation with mass-like intraabdominal abscess by fishbone ingestion in 59-year-old man who presented with a non-tender palpable mass in the left paramedian area and underwent abdominal computer tomography initially reported as showing intraabdominal mass.

강섬유보강 철근콘크리트 일방향 슬래브의 휨거동에 관한 실험 연구

박홍용,문정규 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

Concrete is strong in compression but vulnerable in tension. As a result, crack develops when static loading applied, and failure abruptly appeared when dynamic loading condition. This vulnerability can be improved through the addition of steel fibers in the concrete mix. This experimental test was investigated on the influence of steel fiber reinforcement on flexural behavior characteristics of slabs with various steel fiber contents(Vf) and aspect ratio(ℓ/Φ). Deflection, crack width, and strain of steel bar were measured at every load step. In the results of this experimental test, the addition of steel fibers to conventionally reinforced concrete slab increased the ultimate load, reduced the crack width, the average crack spacing, and deflection.

유압관로내의 동특성을 이용한 비정상 유량계측에 관한 연구

이홍구,윤석주,박성규,박길문 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1

This paper describes an approach for estimating the unsteady flowrate through a hydraulic pipe lines and a components in real time. Concerning the dynamic characteristics of a hydraulic pipe lines, experimental research from the view point of focusing on the unsteady flowrate through a pipe is insufficient because of the lack of adequate flowmeters. In this experiment, a new instantaneous flowrate measurement system making use of a sharp-edged cylindrical choke and LDV has been proposed and developed by the authors. The unsteady flowrate is obtained from the measurements center-line velocity of a circular pipe using LDV and the pressure difference using a sharp-edged cylindrical choke, and experiments on the frequency characteristics are carried out. The results show a good agreement between the estimated and directly measured flowrate waveforms illustrates the validity of the method proposed here.

가을보리 재배기간중의 기상변화

심교문,이정택,윤성호,황규홍 한국농림기상학회 2000 한국농림기상학회지 Vol.2 No.3

The northward shift of the cultivation region of winter barley has been considered because of consecutive warm winters from the middle of 1980's. There was 1.02℃ rise in mean air temperature during winter barley cropping season from 1975 to 1998. During this period, the maximum air temperature affected the mean air temperature rise rather than the minimum air temperature. The amount of mean precipitation was 513.3mm during winter barley cropping season from 1975 to 1998 and was least in 1992. Sunshine hours has increased little by little in the all regions except rural regions. The air temperature during winter barley cropping season from 1987 to 1999 in which the winter was warm was higher than the normal air temperature(1961∼1990). On the other hand, the air temperature during winter barley cropping season from 1974 through 1986 was similar to the normal air temperature. The amount of mean precipitation during winter barley cropping season from 1987 through 1999 was similar to the normal precipitation except April. During this period, the amount of mean precipitation of April was lower by 26mm than the normal year(1961∼1990). Sunshine hours during winter barley cropping season from 1987 to 1999 decreased generally in comparison with a normal year. Considering the air temperature rise during wintering from 1987 to 1998, it might be possible to extend the cropping area of winter barley northward.

한국과 중국의 중학교 전자기학 단원에 대한 비교 분석

김규용,홍문철 濟州大學校 師範大學 科學敎育硏究所 1999 科學敎育 Vol.16 No.-

This study is aimed to compare and analyze the systems of science education of korea and China by the choice of the unit "electromagnetism". The results from the study are as follows : 1. The object of Korea education is similar to that of Chinese education. Both countries have the target to obtain knowledge and technology of science, lead to scientific thought and train ingenious ability to solve the problem But the object of Chinese education emphasize on dialectical materialism patriotism and cultivation of character. So, Educational Institute in China makes efforts to use practical science and technology. And acquisition necessary skill in chines? real life is in accord ith Korean object of technology and industry education 2. The category connected with basic scholastic ability was divided into four categories in the result of the study. Four categories put this order in both countries-(I) knowledge of science, (II) the investigative nature of science, (III) science as a way of thinking, ( IV ) the interaction of science, technology and society. In Korean case, (VI) the interaction of science, technology and society played smaller role than other categories, however it is not important, for it is treated as technology and industry education. Chum and 33 hours in Korea. And Chinese textbook has 2.68pages and Korean textbook has 1.94 3. Chinese textbook has much more lessons and pages than korean textbook when analyze of the amount of it. And the assistant teaching materials of China 1.4 times than those of Korea. 4. In teaching hours assigned to lesson of the electromagnetism about 60 hours are assigned to it in China and 33 houre in Korea. And Chinese textbook has 2.68pages and Korean textbook has 1.94 pages on lesson of the electromagnetism So, the amount of lesson in China is more than that of Korea. To ompare Chinese exact amount of lesson with Korean, We have to considered it in term of the size of textbook and letter, the gap of the line and the content of the assistant teaching materials 5. Many assistant teaching materials are needed to help student understand content of the lesson and produce more effectiveness of the lesson in editing science textbook. It is desirable to provide a lot of deepening lesson and assistant teaching materials to students after the lesson of the electromagnetism And, Learners should choose what they want to study in correspondence with their need and aMity.

한국의 두 강으로부터 재첩의 유전적 종다양성과 열안정성 변이체

허만규,문두호,허홍욱 한국환경과학회 1998 한국환경과학회지 Vol.7 No.3

We examined the genetic variation within the species, the patterns of genetic diversty between populations, thermostability variations of enzymes and temperature tolerances of Corbicula japonica from the two main rivers in Korea. Starch gel electrophoresis was used to examine the genetic variation of 22 loci. Heating experiments of electrophoresis under the condition of 40±5° for 15±5 min disclosed thermostability differences, called heat-sensitive and heat-resistant types, within each electrophoretic allozyme. Genetic diversity at the natural species level was high (77.3%), whereas the extent of heat-treat groups was relatively low (52.6%). The genetic diversity trends to decrease from the source of two main rivers (the Sumjin River and the Nam River) to the mouths. Based on the data available such as considerable high genetic diversity compared with a mean value of C. japonica species, It is recommended that several populations of the species in Korea should be preserved.

병재배 폐톱밥을 이용한 양송이 복토재료 개발에 관한 연구

김홍규,이희덕,김용균,한규홍,문창식,김홍기 충남대학교 생물공학연구소 1999 생물공학연구지 Vol.7 No.-

애느타리 병재배후 탈병한 톱밥을 3월 중순 퇴적하여 부숙시킨 결과 퇴적기간에 따른 폐톱밥의 부숙정도는 퇴적 30일이후에 가장 컸으며 부숙 소요일수는 최소 48일이었다. 퇴적 기간에 따른 폐톱밥의 pH 및 총 질소 함량은 부숙이 진전됨에 따라 증가하는 경향이었고 총 탄소 및 C/N율은 시간이 경과함에 따라 감소하는 경향이었다. 식양토에 부숙이 완료된 톱밥을 부피 비율로 10, 30, 50%씩 첨가하여 복토 재료로 사용한 결과 30% 첨가시 식양토 단용 처리보다 A. bisporus 균사 생장이 촉진되고 초발이 소요일수가 5일 빠르며, 수량에 있어서도 28% 증수되었다. After bottle culture of Pleurotus ostreatus, sawdust was taken out from the bottle and accumulated in the middle of March, and then composted. As the result, Y value was decreased rapidly 30 days after composting, and it was decreased slowly after 30 days. It is considered that 118 days is required for composting, however, it is possible to use for casing material after at least 48 days composting. The pH and total nitrogen content of sawdust based on composting period had tendency to increase as composting was processed. Total carbon and C/N rate had tendency to decrease as time went on. Based on the rate of 10, 30 and 50%, each sawdust was added to clay loam used as casing material for culturing A. bisporrus. Among various treatments, the mycelial growth of A. bisporus was more favorable in the treatment of 30% sawdust than in the single treatment of clay loam. Based on the date necessary for primodium formation of A. bisporus, the primodium formation in the treatment of 30% sawdust was reduced to about 5 days as compared with that of any other treatments When 30% sawdust was added to clay loam used as casing material for culturing A. bisporus, the yield of its fruiting body was increased to 28%.

비알콜성 지방간과 대사성 질환들과의 연관성

김홍규,서찬종,윤효중,황용하,이기영,박혜영,김갑환,강문호 대한내분비학회 2002 Endocrinology and metabolism Vol.17 No.4

연구배경: 비알콜성 지방간은 일반적으로 비만, 제2형 당뇨병 및 고지혈증과 연관성이 있는 것으로 알려져 있으나, 인슐린 저항성과의 독립적인 연관성여부나, 대사 증후군과의 연관성에 관해서는 아직 연구가 많지 않다. 한편, 최근 건강검진센터를 중심으로, 초음파를 이용한 지방간의 진단이 흔하게 되었는데, 이런 대상에서의 지방간의 임상적인 의미에 대해서는 잘 알려져 있지 않았다. 따라서, 본 연구에서는 초음파로 진단된 비알콜성 지방간과 비만, 당대사이상, 이상지질혈증 및 인슐린 저항성과의 연관성을 알아보고, 대사성 증후군과 비알콜성 지방간의 동반정도를 알아보고자 하였다. 방법: 2000년도 4월부터 6월까지 종합건강진단을 위해 가천의대 길병원 건강증진센터에 내원한 262명 중 음주력과 바이러스성 간염, 심한 간기능 또는 신기능이상 및 현성 갑상선기능이상을 보인 147명을 제외한 115명을 대상으로 하였다. 지방간의 진단은 경험 있는 1명의 방사선과의사에 의해 복부 초음파로 진단하였다. 대사성 증후군의 정의는 당대사이상이 있으면서 비만, 이상지질혈증, 그리고 고혈압 중 두 가지 이상의 이상이 있는 경우로 하였다. 결과: 대상자 115명중 비알콜성 지방간이 있는 경우는 30명, 대조군은 85명이었다. 1) 수축기 및 이완기 혈압, 체중, 체질량지수, 체지방량 및 체지방률, 총콜레스테롤과 중성지방, 공복 혈중 인슐린 및 HOMA 인슐린저항성지표는 비알콜성 지방간군에서 의미 있기 높았다. 2) 나이, 성별, 체질량지수, 허리-둔부 둘레비, 체지방량, 체지방률, 공복혈당, 총콜레스테롤, 중성지방, HLD-콜레스테롤, 인슐린, HOMA 인슐린 저항성지표, 그리고 고혈압유무를 포함하여 로지스틱 회귀분석을 실시하였을 때, 체질량지수, 총 콜레스테롤 및 HOMA 인슐린저항성지표가 비알콜성 지방간과 독립적인 연관성이 있었다. 3) 비알콜성 지방간과 대사성 증후군의 연관성을 조사하였는데, 비알콜성 지방간을 가진 사람의 27%에서 대사성 증후군을 동반하였고, 대사성 증후군의 가진 사람의 53%에서 비알콜성 지방간을 동반하였다. 4) 대조군과 비알콜성 지방간군에서 대사성 증후군의 각 구성 인자인 당대사이상, 비만, 이상지질혈증 및 고혈압 중 2개 이상의 인자를 갖는 경우는 각각 28%와 73%로 비알콜성 지방간군에서 현저하게 높았다. 결론: 본 연구의 결과는 비알콜성 지방간이 인슐린 저항성과 독립적인 연관성을 가질 가능성을 시사하였고, 비알콜성 지방간이 있는 경우에 당대사이상, 비만, 이상지질혈증 및 고혈압 중 두 가지 이상의 대사성 질환을 가질 확률이 대조군에 비해 약 3배나 높음을 보여주었다. 따라서, 비알콜성 지방간으로 진단된 환자들에서 이러한 대사성 질환들에 대한 적절한 평가와 이를 호전시키기 위한 노력 및 주의 깊은 경과관찰이 필요할 것으로 생각되었다. Background: Non-alcoholic fatty lever disease (NAFLD) is known to be frequently associated with obesity, type 2 diabetes and dyslipidemia. Recently, the diagnosis of fatty lever disease, based on ultrasonographic findings, has increased. Therefore, we examined the association between NAFLD and various metabolic disease, such as obesity, glucose intolerance, dyslipidemia, and hypertension or metabolic syndrome, and tried to find out whether NAFLD was independently related to insulin resistance. Methods: From April to June 2000, 262 subjects, attending for routine physical check-ups, were screened. Of these, 115 one hundred fifteen subjects were studied, with the other 147 excluded due to significant alcohol consumption, evidence of viral or toxic hepatits, significant liver or renal dysfunction, and overt thyroid disease. Fatty lever was diagnosed if the subject had a 'bright' liver on ultrasonographic examination. All diagnoses were made by a singled experienced radiologist. Results: of the 115 subjects. 30(26%) showed NAFLD. 1. Systolic and diastolic blood pressures, body weight, serum total cholesterol, triglyceride, fasting insulin levels, and HOMA IR (homeostasis model assessment insulin resistance index) were higher in the subjects with NAFLD than in the controls. 2. Multiple logistic regression analysis, including age, sex, BMI, waist to hip ratio, fasting serum, glucose, lipids and insulin levels, HOMA IR, and hypertension showed that BMI, total cholesterol and HOMA IR were independently related with NAFLD. 3. 27% of the subjects with NAFLD showed metabolic syndrome, and 53% of subjects with metabolic syndrome had NAFLD. 4. The percentage of subjects who had more than two factors of metabolic syndrome was three times higher in the subjects with NAFLD compared to the controls. Conclusion: These results suggest that NAFLD may be independently related with insulin resistance. Metabolic diseases, such as glucose intolerance, obesity, dyslipidemia and hypertension, were more prevalent in the subjects with NAFLD than in the controls. Therefore, we should try to assess the status of the metabolic disease, and treat them in patients with NAFLD (J Kor Soc Endocrinol 17:526∼534, 2002).