간행물
한국지구과학회지 KCI 등재 The Journal of The Korean Earth Science Society
- 발행기관 한국지구과학회
- 자료유형 학술지
- 간기 격월간
- ISSN 1225-6692 (Print)2287-4518 (Online)
- 수록기간 1979 ~ 2024
- 주제분류 자연과학 > 지구과학 자연과학 분류의 다른 간행물
- 십진분류KDC 450DDC 550
권호리스트/논문검색
제13권 제1호 (1992년 3월) 10건
1.
1992.03
구독 인증기관 무료, 개인회원 유료
Denitrification activity of microbial communities in sand-gravel sediments and biofilms developing on a concrete riverbed of an urban small stream, Nogawa River, was measured monthly by laboratory incubations after the acetylene inhibition technique during une year from December 1987. The annual mean denitrification rate of the biofilm samples, 1.5 mgN m-2 h-1. was higtrer than the rate ut the sandgravel sediment samples. 0.8 mgN m-2 h-1. Contrary, ratios of the denitrified nitrogen to the total inorganic nitrogen fluxes was lower at the stretch where an attached microbial community developed un the concrete riverbed the stretch with sand-gravel riverbed. The longer residence times of water masses ut the site with a sand-gravel riverbed is responsible for the above relationship. Based on the average denitrifieation rates, if all the channel of Nogawa River were covered with concrete, the proportion of denitrified nitrogen to the input nitrogen should decrease to 1.3 %, whereas the ratio is 2.5% when the riverbed is composed of sands and gravel. The results suggest that the efficiency of nitrogen removal by benthic denitrification is strongly affected by the structure of a channel of the river.
4,000원
2.
1992.03
구독 인증기관 무료, 개인회원 유료
Several subjects related to gravity terrain correction, such as segmentation and geometric fitting of topography, methodology of gravity effect calculation, and difference between slab and spherical shell type corrections, are widely reviewed. Through the review, an effective terrain correction program in which accuracy in the correction is balanced with simplicity in excution is developed. The program written in microsoft Fortran for general use appears to be effective in the viewpoint of accuracy as well as simplicity. Topography data file which is convenient in management and retrieve is designed for the excution of the program. It is required for estimating terrain and Bouguer correction values to assume the mean density which should effectively be used over the area concerned. The preexisting methods for the density determination are examined and an alternative method modified the preexisting ones is proposed in the present study.
4,000원
3.
1992.03
구독 인증기관 무료, 개인회원 유료
An attenuation profile of young uppermost oceanic crust was obtained using ocean bottom seismometers and explosive sources detonated near the ocean bottom. The quality factor (Q) increased from 6 at the sea floor to 50 at a depth of 500 m. The mechanisms of high attenuation obtained in this experiments was inferred by examining several attenuation mechanisms such as frictional dissipation, viscous shear flow, liquid squirt mechanism and scattering by small pores and large cracks. Comparison of the attenuation value in this experiment and those from other experiments was also used to clarify the mechanism of the high attenuation. Of those mechanisms mentioned above, frictional dissipation, viscous shear flow and scattering do not seem to be the cause of the high attenuation in the uppermost oceanic crust where many small pores and large scale cracks are developed. The most viable mechanism in the young uppermost oceanic crust seems to be liquid squirt mechanism.
4,000원
4.
1992.03
구독 인증기관 무료, 개인회원 유료
A magnetic survey was carried out at the Barton Peninsula in King George Island, Antarctica. To analyze geological features in the study area, several filtering methods in 2-dimensional wavenumber domain were used. The Barton Horst associated with volcanic activities is well revealed on the low-pass filtered anomaly map. Possible existence of small volcanic plugs or, presumably, mineralized zones are apparent at northern parts and south-western part by reduction-to-the-pole and pseudo-gravity filtering. On the 1st vertical derivative and directional filtered anomaly maps, the geological boundaries on the surface are well identified, and fault strikes along E-W or NW-SE direction appeared to be mostly dominant throughout the study area. Density and susceptibility mapping were performed using the inversion method. The apparent densities of tuffaceous rocks distributed in the southern parts and those of quartz-diorite or crystal tuff in the northern parts were computed as values up to about 2.69 g/㎤ and 2.73 g/㎤, respectively, and the apparent susceptibilities of those rocks are appeared to be about 250 × 10^(-6) CGS and 1870 × 10^(-6) CGS, respectively. These results are in accordant with those of samples measured by Garrett(1990). Therefore, it is concluded that the studied area of the Barton peninsula has been influenced by crustal movement associated with active volcanism and the surface lithology is extended to the considerable depth.
4,300원
5.
1992.03
구독 인증기관 무료, 개인회원 유료
The stratigraphy and evolution of the intertidal deposit of Gunhung Bay, west coast of Korea, have been studied by analyzing surface sediments, core sediments and subbottom profiles. The surficial sedimentary facies consists of upper mudflat, mixedflat and lower mudflat from high tide level to low tide level. The tidal deposit above the acoustic basement is 5 - 20m thick and can be divided into two sedimentary sequences by a mid-reflector. The boundary of them is identified by long core data. The lower sedimentary unit (sequence B) consists of semi-consolidated, brown sandy muds and is interpreted to be deposisted during Riss-Wurm interglacial period. The upper sedimentary unit(sequence A), which overlies the sequence B unconformably, is about 10m thick and consists of Holocene intertidal sediments. The sequence A consists of mudflat facies at lower part and mixedflat facies at upper part. It indicates that the sequence A is a transgressive sequence. Many V-shaped erosional patterns at the unconformable contact of sequence A and sequence B indicate the existence of old tidal channels formed during the low sea level of the last glacial period. The long-term accumulation rate of sequence A is considered to be 2㎜/yr from core data and it is coincident with the accumulation rate determined by Pb-210 for the PVC core.
4,300원
6.
1992.03
구독 인증기관 무료, 개인회원 유료
A previously unreported sedimentary complex has recently been discovered in the northern part of Choˇnsu Bay. It overlies both unconformably the Precambrian low-grade metamorphosed sedimentary sequence(Taean Formation) and the Jurassic biotite granite. The sedimentary complex is proposed to be designated as Choˇnsuman Formation. The Formation is composed of conglomerate, tuff, basalt, tuffbreccia, and shale. It is distributed in the northwest and northeast coasts of Choˇnsu Bay and in the Chukdo. Age of the Formation seems to be of late Mesozoic. The Choˇnsu sedimatary basin is considered to be originated by block faulting presumably during the Cretaceous, as suggested by the development of N-S trending structural lineation in the study area and its vicinity. The Chonsuman Formation seems to be formed by sedimantation in close association with block faulting and volcanic activities nearby. Sedimentation is thought to be developed from west to east in the basin.
4,500원
7.
1992.03
구독 인증기관 무료, 개인회원 유료
One genus and two species of fusulinids are collected and described from the upper part of the limestone of the Gabsan Formation, Jecheon area, Chungbuk. The identified fusulinids are Profusulinella arta, Profusulinella wangyui and enable to establish the Profusulinella Zone. This zone is able to correlate with the lower part of Profusulinella Zone in Yeongweol coalfield, the Eostaffella subsolana subzone in Samcheog coalfield, the Profusulinella Zone in U.S.A., the Eostaffella subsolana subzone in China and the lower part of the Profusulinella Zone in Japan. The geologic age of the upper part of the limestone of the Gabsan Formation will be the Lower Moscovian. Though any fusulinids are not found from the lower part of the limestone of the Gabsan Formation, the geologic age of the lower part of the Gabsan Formation would be the Bashkirian. Because the lithostratigraphic sequence is very similar to that of the Yobong Formation in Yeongweol coalfield.
4,000원
8.
1992.03
구독 인증기관 무료, 개인회원 유료
It has been reported that students hold various intuitive ideas about classroom experiences as well as natural phenomena. In addition, students may hold intuitive ideas about some means of science instruction. Two everyday devices, such as a humidifier and an electric heater, were investigated in terms of students' intuitive ideas. A total of 36 students (nine students from each of the following level; fifth-, eighth-, eleventh-grades, and college) were selected from the Central Texas Area. The researcher interviewed each subject. Less than 30 percent of the subjects believed that prolonged use of an electric heater in a closed small room will lead to the decreament of humidity in the room. However, only two students were aware that increased temperature lowers the humidity. Students held two major intuitive ideas about humidifier: human-centered and air-centered. The subjects who held human-centered views about humidifier believed that a humidifier clears human throats and lungs, or helps people to breathe easier. The subjects whose ideas were categorized as air-centered responded that a humidifier generates oxygen, cleans air, or provides moisture into the air. Higher grade students held more sophisticated ideas about electric heater and humidifier. Students' intuitive ideas about electric heater and humidifier were qualitatively different from those expected. Therefore, everyday devices which may be frequently used for science instruction should be investigated in terms of students' intuitive ideas. At the same time intuitive ideas about such devices should be incorporated into the planning of science instruction, curriculum design, and teacher education.
4,000원
9.
1992.03
구독 인증기관 무료, 개인회원 유료
The purpose of the study is to provide meaningful suggestions according to the theoretical backgrounds and the scholastic characteristics and the present status of earth science education as a field of subject lesson education. Based on the results presented, the following are the conclusions and suggestions of this study. 1. Based on the scholastic characteristics, earth science plays a role as a subject content education, and earth science education functions a leading part as a subject lesson education. Accordingly, this might be an essential field for training earth science teacher with education. 2. It is thought that the educational goals of the department of earthscience education might be trained to be in an earth science educator rather than earth scientist or natural scientist. 3. It is thought that the solid background to the subject contents is essential for becoming earth science teacher. For the reason, the curriculum for training earth science teachers needs to be reformed to what extent like the criterion of the department of natural science. If it is really in a difficult matter, it might be effective for training earth science teacher to take the course work of science content related in the department of natural science under the equal circumstances. 4. It is considered that the curriculum of the department of earth science education might be organized according to the integrated subject lesson education rather than separate subject content education. 5. It is thought that the suggestions presented above will be accepted as the real worth of teacher training school and its pursuing goals are recognized as it is.
4,000원
10.
1992.03
구독 인증기관 무료, 개인회원 유료
The magnetogram inversion technique (MIT) has been demonstrated as a powerful $quot;remote sensing tool$quot; in estimating ionospheric quantities, such as ionospheric current, field-aligned current, electric potential and Joule heating rate etc. Furthermore it is now possible to infer instantaneous patterns of such global distributions with a high time resolution (say, 5 min) through the numerical method. However, the electric potential distribution estimated from the MIT is very sensitive to the choice of ionospheric conductivity models. It is a serious drawback of the method, since the electric potential over the polar region is a very important quantity reflecting the efficiency of the solar wind-magnetosphere coupling. Thus a realistic conductivity distribution over the entire polar ionosphere is acute. In this paper, we introduce a general concept of ionospheric electric conductivity along with several methods of estimating it.
5,200원
