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.

Korea Pathfinder Lunar Orbiter (KPLO) Operation: From Design to Initial Results

Moon-Jin Jeon,Young-Ho Cho,김은혁,Dong-Gyu Kim,Young-Joo Song,홍승범,Jonghee Bae,Jun Bang,Jo Ryeong Yim,Dae-Kwan Kim 한국우주과학회 2024 Journal of Astronomy and Space Sciences Vol.41 No.1

Korea Pathfinder Lunar Orbiter (KPLO) is South Korea’s first space exploration mission, developed by the Korea Aerospace Research Institute. It aims to develop technologies for lunar exploration, explore lunar science, and test new technologies. KPLO was launched on August 5, 2022, by a Falcon-9 launch vehicle from cape canaveral space force station (CCSFS) in the United States and placed on a ballistic lunar transfer (BLT) trajectory. A total of four trajectory correction maneuvers were performed during the approximately 4.5-month trans-lunar cruise phase to reach the Moon. Starting with the first lunar orbit insertion (LOI) maneuver on December 16, the spacecraft performed a total of three maneuvers before arriving at the lunar mission orbit, at an altitude of 100 kilometers, on December 27, 2022. After entering lunar orbit, the commissioning phase validated the operation of the mission mode, in which the payload is oriented toward the center of the Moon. After completing about one month of commissioning, normal mission operations began, and each payload successfully performed its planned mission. All of the spacecraft operations that KPLO performs from launch to normal operations were designed through the system operations design process. This includes operations that are automatically initiated post-separation from the launch vehicle, as well as those in lunar transfer orbit and lunar mission orbit. Key operational procedures such as the spacecraft’s initial checkout, trajectory correction maneuvers, LOI, and commissioning were developed during the early operation preparation phase. These procedures were executed effectively during both the early and normal operation phases. The successful execution of these operations confirms the robust verification of the system operation.

척수 경막외 혈관 기형에 의한 재발성 척수병증

오동호,김희태,박운규,이영주,김승현,김주한,김명호,박문향 대한신경과학회 1998 대한신경과학회지 Vol.16 No.5

포기/비포기 시간비가 활성슬러지 floc의 특성에 미치는 영향

김강호,문병현,이택순,서규태 7개 국립대학교 환경연구 논문집 공동발행 위원회 2002 환경연구논문집 Vol.2 No.1

Many researches on SBR(Sequencing batch Biological Reactor) for the removal efficiency of contaminants and effects of operation mode in effluent have been conducted. However, little studies for the characteristic of biological floc affected by operation mode have been made. The purpose of this study is to compare the effect factors on the removal efficiency of nitrogen and phosphorus in SBR system. And also it is to look for new information on the size and characteristics of biological floc by changed aerobic/anaerobic time ratio. Results shown that the removal efficiency of organic matter, nitrogen and phosphorus was higher in the operation mode of higher aerobic/anaerobic time ratio. The floc size and fractal dimension produced in higher aerobic/anaerobic time ratio were larger. These result implied that the settling characteristics of floc could be produces in the operation mode of higher aerobic/anaerobic time ratio.

벽체에 작용하는 토압에 관한 모형실험

김문규,김대현 동의공업대학 2000 論文集 Vol.26 No.1

The model experiments were carried out to observe the variation of lateral earth pressure acting on the wall as vary the constraint of retaining wall, geometry of wall, and backfill width. For the experiments, a soil-box, model wall, and a rainer were designed and manufactured. The experiments were carried out with two different types of constraint on wall movement: i.e. first with completely fixed wall and second with movable wall depending on soil pressure. The measured lateral earth pressure was compared with that by an extended silo and wedge theories. The test results are summarized as follows: The measured lateral earth pressure approached to that from the extended silo theory as a narrower backfill width was used. Both experimental and theoretical results showed a good coincidence when the backfill width is Bc tan(45 -?? DS/2)H. But much deviated from that by an extended wedge theory. (원문을 참조하세요)

핵산의 절단을 유발하는 전이금속착화합물의 합성

김희정,이범규,고문주 조선대학교 환경연구소 2000 環境硏究 Vol.16 No.1

Study on the synthesis of chemical nucleases that have ability of cleavage of RNA or DNA to investigate the structure of nucleic acids was performed. We synthesized Ni-complex that was synthesized by Karn and Busch (1966) and identified the specificity and ability as chemical nuclease by Chen et. al. (1993), and Cu-complex and Cd-complex that were presumed as having specificity similar to Ni-complex in terms of the structure and specificity and ability as chemical nuclease. The spectra of synthesized new transition metal complexes were compared with those of Ni-complex. Results of comparing data of UV and IR spectra of Cu-complex and Cd-complex with those of Ni-complex showed that the structures of newly synthesized transition metal complexes were similar to the structure of Ni-complex. The yield of synthesis of Ni-complex, Cu-complex, and Cd-complex was 81%, 7%, and 39% respectively.

淨水슬러지의 固化處理에 關한 硏究

김대현,김문규,임성진 동의공업대학 2000 論文集 Vol.26 No.1

The purpose of this study is to determine the possibility of using as a fill material and cover soil, hardened up to a specific age by making a dosing such as slaked lime, bentonite into the sludge generated during waterworks treatment process with existing treatment system of a ocean dumping. For these reasons, this study carried out a basic physical property test, consolidation test, unconfined compression strength test, extraction test on heavy metals, X-ray diffraction analyzer, scanning electron microscope to determine a characteristic of modified waterworks sludge. In this case that waterworks sludge was modified by being mixed with slaked lime accounting for 10% of its total amount at the age of twenty eight day, the compression strength of the sludge was developed 1.0kgf/㎠ or over. This indicated that the sludge could be used as fill material and cover soil. The extraction test on waterworks sludge modified by slaked lime showed the below of KSP, TCLP standard. Estimation of coefficient of permeability as consolidation test showed less considerably in comparison with reported coefficient of permeability at the landfill site in Seoul Metropolitan area. For this reason, it was found that modified waterworks sludge could be used as fill material and cover soil. Accordingly if waterworks sludge was reused by hardening process, showing a more effecting in terms of economy, environment.

耽 羅 方 言 試 攷

金文奎 圓光大學校 1960 論文集 Vol.2 No.-

입원환자 낙상 발생 실태와 원인에 관한 분석 연구

김철규,서문자 한국의료QA학회 2002 한국의료질향상학회지 Vol.9 No.2

Background : The purpose of this research was to examine the fall incidence rate and its related factors of fall in inpatients. Methods : The data were collected from the 138 fall incident reports in one tertiary hospital in Seoul from April 1st 1999 to September 30th 2001. The Fall Incident Report Form was originally developed based on that of Massachusetts General Hospital revised in 1995. And this was modified for this survey by the collaborating work of QI team including researcher and department of nursing service of this particular hospital. The contents of Fall Incident Form were general characteristics of patient, factors related to fall, types and places of fall, circumstances, nursing interventions, and outcome. Results : 1)the incidence rate of fall was 0.08% of total discharged patients and 0.081 per 1000 patient-day. This incidence rate is much lower than that of general hospitals in USA. This finding might result from the different incidence report system of each hospital. 2)The characteristics of fall-prone patient were found as follows. They were mostly over 60 years old, in alert mental status, ambulatory with some assistance, and dependent on ambulatory device. The types of diseases related high incidence rate were cerebrovascular disease(3.2), hypertension(1.6), cardiovascular disease(1.4), diabetes(1.3) and liver disease(0.6). 3)The majority of fall events usually occurred in bed, beside(walking or standing)and bathroom in patient room. Usually they were up on their own when they fell. And there were more falls of elderly occurred during night time than day or evening. 4)63.8% of fall events resulted in physical injuries such as fracture and usually the patients had diagnostic procedures and some treatment(ex.suture)which caused additional cost to the patients and their families. 5)The found risk factors of fall were drugs(antihypertensive drug, diuretics)and environmental factors like too high bed height, long distance of bedside table and lamp switch, and slippery tile of bathroom floor. Conclusion : Considering these results, every medical and nursing staff should be aware of the risk factors of patients in hospital, and should intervene more actively the preventive managements, specially for the elderly patients during night. Therefore, it is recommended that the development of Fall Prevention Programs based on these results.

삼차원 초음파를 이용한 체적 측정

김표년,이홍재,정융기,이문규,하현권,오용호 대한초음파의학회 1998 ULTRASONOGRAPHY Vol.17 No.1