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제주도 서귀포지역 제4기 퇴적층에서 산출된 포자·화분의 고기후적 의미
정철환,윤호일,이승현 한국지구과학회 2004 한국지구과학회지 Vol.25 No.5
Palynoflora from a core (BH-4) drilled on the Quaternary sediments in the vicinity of Seogwipo, Jeju Island, provide an unusual opportunity to reveal vegetational transition from the last glacial to the Holocene in Korea. It consists mainly of ferns, deciduous broad-leaved angiosperms, and herbs, and is represented by Polypodiaceae, Gramineae, Castanea/Castanopsis, Quercus and Compositae. A distinct vegetational change is observed at a core depth of 200 cm. The interval of 30 to 190 cm in depth yields mainly arboreal pollen and warm temperate taxa such as Polypodiaceae, Ceratopteris, and Taxodiaceae - Cupressaceae - Taxaceae, whereas the interval of 200 to 800 cm is dominated by herbaceous pollen and a decrease of warm temperate taxa, reflecting the influence of cold climate. This palynofloral climatic signature closely corresponds to paleoclimate proxy records such as magnetic susceptibility.
정철환,강호만,이윤식 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Photoacoustic (PA) imaging is very promising technique, based on the generation of ultrasonic wave after irradiation of a light to a material. PA signal has high resolution and great penetration depth, because the degree of ultrasonic scattering is lower than that of fluorescence. Therefore, it is known to be very powerful tool for in vivo imaging. On the other hand, SERS nanoprobe is continuously receiving high attention as an outstanding nanomaterial for multiplexed detection of target bio molecule. SERS signals do not have photobleaching problem, and have much narrower peak width than fluorescence. Herein, we have synthesized near-IR nanoprobe which can generate both PA and SERS signals. The nanoprobe is biocompatible due to the hydrophilic surface modification, and is expected to be an effective tool for in vivo imaging and multiplexed detection.
제7차 교육과정 지구과학 관련 교과서에서의 화석사진에 대한 산출지역 및 척도 표기 분석
정철환,문병찬,김해경 한국지구과학회 2005 韓國地球科學會誌 Vol.26 No.6
Fossil photographs in science and earth science textbooks on the 7th curriculum including those of elementary,middle and high school, are analyzed to estimate the adequacy and scientific significance focusing on the locality andscale. The results show that most of the textbooks have included various types of fossil photographs: 32 in elementaryphotographs is insuficient. Only 68% of the elementary textbooks designates locality and only 6% includes scales.Among middle and high school textbooks, 40 and 16% of photographs describe locality, and 14 and 18% of photographsexhibit scale, respectively. More scientific and appropriate presentation of fossil photographs, such as locality and scale, isneeded to enhance educational effect 제7차교육과정의초등학교과(‘) 학’ ‘실험관찰’ 교과서와서로다른출판사의중·고등학교과학과지구과학 I, II 교과서, 각 4권씩을대상으로교과서에수록된화석사진을분석하여화석의종류, 산출지역과척도의표기에대한분석결과다음과같은결론을얻었다. 초등학교의과(‘) 학’, ‘실험관찰’ 교과서에수록된화석사진의종류는 32개였으며, 중학교과학교과서 4권에는 50개, 그리고고등학교 8권의교과서에서는 109개였다. 그러나화석사진에서표현되는과학적정보는부족하였다. 초등학교의과학교과서와실험관찰에서는수록된화석사진의 68%에산출지가표기되어있었으며,척도가표기된화석사진은전체의 6%였다. 중학교와고등학교교과서의경우, 전체화석의 40%와 16%에산출지가표시되어있으며, 척도는 14%와 18%만이표기되어있었다. 보다효과적인과학교육의목표를달성하기위해과학교과서에수록된화석사진에산출지와척도를표기할필요가있다.
정철환,김정빈 한국지구과학회 2017 韓國地球科學會誌 Vol.38 No.7
This study investigates the development process of Mt. Deok on Bigeum Island, Shinan, on the basis of geomorphological and geological analyses. K-Ar dating was carried out on two samples of the acidic lapilli tuff developed in the study area, and the obtained K-Ar ages are 70.4±1.4 and 76.9±1.5 Ma, which correspond to the Late Cretaceous (Campanian). Mt. Deok is surrounded by rock cliff, and various weathering microtopographic features, such as tafoni, tor and gnamma, are developed. Tafoni with diverse morphologic types is the most dominant feature, indicative of intense salt weathering. Geological characteristics such as porous tuff and joint have played an important role in the development of tafoni and rock cliff. Geomorphology and geology of Mt. Deok reflect paleoenvironmental change and interaction between human and nature in the coastal area. 이 연구에서는 전라남도 신안군 비금도의 덕산에 대한 지형 및 지질학적 분석을 통하여 그 형성과정을 고찰하였다. 연구지역에 분포하는 산성 라필리응회암에 대한 K-Ar 연대측정을 실시하였고, 중생대 백악기 말(Campanian)에해당하는 70.4±1.4 Ma 내지 76.9±1.5 Ma의 연대를 얻었다. 덕산은 암반절벽으로 둘러싸여 있으며 타포니, 토르, 나마와 같은 풍화 미지형이 발달되어 있다. 특히 다양한 형태의 타포니가 발달되어 있어 활발한 염풍화의 영향을 지시하고있다. 다공질의 응회암 및 절리의 발달과 같은 지질학적 특성이 타포니와 암반절벽 등의 지형 형성에 중요한 영향을준 것으로 판단된다. 덕산의 지형 및 지질은 과거 환경변화와 해안지역에서의 인간과 자연의 상호작용을 보여주고 있다.
정철환 한국지질과학협의회 2011 Geosciences Journal Vol.15 No.3
To investigate the Holocene vegetation and climate changes, pollen analysis performed on swamp deposits of the Boseong area, South Korea. From ca. 11,800 to 10,500 cal. yr BP, a cool temperate deciduous broadleaved forest dominated by Alnus and Quercus (Lepidobalanus) occupied the study area, indicating climatic warming during the Preboreal (earliest Holocene). A remarkable decrease in riparian Alnus and an increase in xerophytic Artemisia from ca. 10,500 to 8,400 cal. yr BP suggest open woodland with herbaceous understory reflecting a cool and dry condition. The expansion of deciduous broadleaved forest combined with rise in evergreen broadleaved taxa and the retreat of grassland between ca. 8,400 and 3,700 cal. yr BP indicate a vegetation shift from open woodland with herbaceous understory to warm temperate evergreen and deciduous broadleaved forests, resulted from climate amelioration during the Holocene climatic optimum. A warm and humid condition during this period is also evidenced by high values of pollen concentration. Vegetation change controlled by human impact occurred from ca. 3,700 to 2,900 cal. yr BP, as indicated by a rise in Pinus and Polypodiaceae and by high sedimentation rate. Along with the late Holocene climatic cooling, human impact brought about the development of Pinus dominated open woodland with a fern (Polypodiaceae) understory in the Boseong area
출력 시간지연을 이용한 이산시간 선형시스템의 최적 출력제어
정철환,Jung, Chul-Hwan 대한전자공학회 1989 전자공학회논문지 Vol. No.
본 논문에는 순간출력에 시간지연이 있는 출력을 첨가시킨 새로운 제어법칙을 제안하였다, 제안된 시스템을 해석하기 위하여 시간지연이 없는 시스템으로 변환하는 방법도 제시 하였다. 여기서 제안된 제어법칙은 순간 궤환제어법칙보다 시스템의 응답특성을 개선시킬 수 있었음을 컴퓨터 시뮬레이션으로써 일예를 들어 확인 하였다. This paper proposed the new control law which is defined by instantaneous output and time delayed output. To analyze the system with time delayed output, the way which transforms output time delayed systEms into instantaneous output systems is presented. The output responses were more improved by the new control law thEn that of the instantaneous output control law. The algorithem for simulation and a numerical exemple are presented.