• Journal of The Korean Astronomical Society
• /
• v.10 no.1
• /
• pp.23-30
• /
• 1977

We have collected times of minimum light available in the literature for WZ Andromedae and analyzed the nature of the period variations. The O-C diagram of WZ And clearly shows that two abrupt changes near JD 2418000 and JD 2435000 are deduced by dp/p=$+4.24{\timesa}10^{-6}$ and dp/p=$-2.46{\times}10^{-6}$, respectively. For these period changes, we have introduced the equations which represent mass exchange in the close binery systems given by Biermann and Hall (1973), and the computation yieleled a mass flow of $7.42{\times}10^{-5}M$. from the hotter component to the cooler one. Due to the amount of mass flow, the period decrease may also be calculated. The theoritical new period after JD 2435000 became 0.69565858 days, which is in good agreement with the value 0.69566034 days found in the O-C diagram. In this computation, the mass ratio of WZ And suggested that the hotter star is the filling its Rochclooe, and thus WZ And is in Paczynski's stage II.

• 한국지구과학회:학술대회논문집
• /
• 2010.04a
• /
• pp.21-21
• /
• 2010

천연기념물 제395호 진주 가진리 새발자국과 공룡발자국 화석산지는 1997년 5월 20일, 경남과학교육원 신축 공사장에서 당시 경남과학고등학교 교사로 근무하던 백광석(현재 서상중고등학교 교장)에 의해 최초로 발견되어, 수 백 점의 새발자국 화석과 공룡발자국 화석들이 학계에 알려지게 되었다. 지금까지도 세계 여러나라의 중생대 새 발자국 중에서 가장 밀도가 높은 화석산지로 손꼽히고 있으며 많은 학자들의 관심을 받고 있다. 이곳의 지질은 백악기 하양층군 함안층 하부의 적색 이암 또는 셰일과 사암의 호층으로 구성되어 있고, 새발자국 화석들은 적색 이암에서 발견된다. 현재, 이 화석산지는 경남과학교육원 건물 내부에 위치하고 있으며, '화석문화재전시관'이라는 명칭으로 보호 및 관리되고 있기때문에 자연재해와 풍화에 의한 침식을 1차적으로 막고 있다. 이 화석산지는 우리나라에서는 천연기념물 제394호 해남 우항리 화석산지와 함께 현장을 그대로 보존하면서 화석의 보존과 관리를 동시에 할 수 있는 건물을 지어 자연사교육을 진행할 수 있는 곳으로 많은 학생들을 대상으로 우리나라의 소중한 화석을 직접 관찰하고 학습하는 체험교육이 가능하다. 원격조종카메라 시스템을 활용하여 관람객이 직접 자신이 원하는 발자국 화석을 세부적으로 관찰할 수 있게 장치한 interactive system은 과학교육 효과를 증진시킨다. 선행 연구에 의하면, 본 화석산지에서 익룡의 발자국 화석(KS 071)도 공룡이나 새발자국과 같은 층리면에서 서로 겹쳐서 나타난다고 보고되었으나, 본 연구에 의해 다시 조사된 결과 전형적인 익룡의 발자국 화석에서 보이는 분명한 특징들을 발견할 수 없었다. 물갈퀴를 가진 새발자국 가운데에서 Uhangrichnus chuni 와 Jindongornipes kimi 로 기재된 표본들에 대하여서도 새롭게 분석하였다. Uhangrichnus chuni로 기재된 많은 표본들은 II-IV번 발가락 사이의 각, 물갈퀴의 형태, 뚜렷한 hallux 등의 형태적 특징을 근거로 할 때, 대부분이 Ignotorinis yangi로 판단된다. Jindongornipes kimi로 기재된 표본들은 이미 기재된 표본보다 크기가 적어도 10%-25%가 작으며, II-IV번 발가락 사이의 각에서 차이를 보인다.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_2
• /
• pp.1891-1900
• /
• 2021

Fine particulate matter (FPM; diameter ≤ 2.5 ㎛) is frequently found in metropolitan areas due to activities associated with rapid urbanization and population growth. Many adolescents spend a substantial amount of time at school where, for various reasons, FPM generated outdoors may flow into indoor areas. The aims of this study were to estimate FPM concentrations and categorize types of FPM in schools. Meteorological and chemical variables as well as satellite-based aerosol optical depth were analyzed as input data in a random forest model, which applied 10-fold cross validation and a grid-search method, to estimate school FPM concentrations, with four statistical indicators used to evaluate accuracy. Loose and strict standards were established to categorize types of FPM in schools. Under the former classification scheme, FPM in most schools was classified as type 2 or 3, whereas under strict standards, school FPM was mostly classified as type 3 or 4.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.2
• /
• pp.37.3-38
• /
• 2021

One of the key questions on star formation is how the organic molecules are synthesized and delivered to the planets and comets since they are the building blocks of prebiotic molecules such as amino acid, which is thought to contribute to bringing life on Earth. Recent astrochemical models and experiments have explained that complex organic molecules (COMs; molecules composed of six or more atoms) are produced on the dust grain mantles in cold and dense gas in prestellar cores. However, the chemical networks and the roles of physical conditions on chemistry are not still understood well. To address this question, hot (> 100 K) cores in high mass young stellar objects (M > 8 Msun) are great laboratories due to their strong emissions and larger samples than those of low-mass counterparts. In addition, CH₃OH masers, which have been mostly found in high mass star forming regions, can provide constraints due to their very unique emerging mechanisms. We investigate twelve high mass star forming regions in ALMA band 6 observation. They are associated with 44/95 GHz Class I and 6.7 GHz Class II CH3OH masers, implying that the active accretion processes are ongoing. For these previously unresolved regions, 66 continuum peaks are detected. Among them, we found 28 cores emitting COMs and specified 10 cores associated with 6.7 GHz Class II CH3OH masers. The chemical diversity of COMs is found in cores in terms of richness and complexity; we identified up to 19 COMs including oxygen- and nitrogen-bearing molecules and their isotopologues in a core. Oxygen-bearing molecules appear to be abundant and more complex than nitrogen-bearing species. On the other hand, the COMs detection rate steeply grows with the gas column density, which can be attributed to the effective COMs formation in dense cores.

• Journal of the Korean earth science society
• /
• v.29 no.6
• /
• pp.454-465
• /
• 2008

Benthic foraminiferal assemblage and AMS radiocarbon dating of core sediments from the northern shelf of the East China Sea were analyzed in order to understand the paleoenvironment and sedimentary environmental changes around the Korean marginal seas since the last glacial maximum (LGM). The core sediments, containing continuous records of the last 16,000 years, reveal a series of well-defined vertical changes in number of species (S), P/T ratio and species diversity (H) as well as foraminiferal assemblage. Such down-core variations display a sharp change at a core depth of approximately 240 cm, which corresponds to ca. 10,000 year B.P. The sediments of the lower part of the core (240${\sim}$560 cm, Zone I), including the well-developed tide-influenced sedimentary structures, are characterized by high abundances of Ammonia beccarii and Elphidium clavatum (s.l.) and low values in number of species, P/T ratio and diversity. These tide-influenced signatures and foraminiferal assemblage characters suggest that the sediments of Zone I were deposited in a coastal environment (water depths of 20${\sim}$30 m) such as tidal estuary with an influence of the paleo-rivers (e.g., old-Huanghe and Yangtze rivers) during the early phase of the sea-level rise (ca. 16,000 to 10,000 years) since the LGM. In contrast, the upper core sediments (0${\sim}$240 cm, Zone II) are characterized by abundant Eilohedra nipponica and Bolivina robusta with a minor contribution of A. ketienziensis angulata and B. marginata. and high values in number of species, P/T ratio and diversity. Based on relative abundance of these assemblage, Zone II can be divided into two subzones (IIa and IIb). Zone IIa is interpreted to be deposited under the inner-to-middle shelf environment during the marine transgression in the early Holocene (after ca. 9,000 yr B.P.) when sea level rapidly increased. The sediments of zone IIb most likely deposited after 6,000 yr B.P. under the outer shelf environment (80${\sim}$100 m water depth), which is similar to modem depositional environments. The muddy sediments of zone IIb were probably transported from the old-Huanghe and Yangtze Rivers during the late Holocene. We suggest that the present-day oceanographic conditions over the Yellow and the East China Seas have been established after ca. 7,000${\sim}$6,000 yr B.P. when the Kuroshio Current began to influence this area.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.17 no.5
• /
• pp.79-89
• /
• 2014

This study was carried out to provide basic information to improve the surrounding ecosystems with benefit analysis and monitoring in cut slopes following establishment of a test construction to improve ecological environment in slopes of an expressway. Field tests from October 2012 to May 2013 were conducted in Seosejong IC and Shinyang IC. In order to improve the view of slopes, soil condition is an important factor. The earth slope, it is possible to introduce directly the plant. Stable construction method was applied, another foundation for planting is necessary. The mixing ratio of the seeds according to the experimental results, the difference was found at an early stage plants in Site I (Seosejong IC). Trees were planted on terraced structures were well coordinated and pictures. The growth of planted trees was good in Site II (Shinyang IC). Due to the use of plants in the landscape will continue to change. Thus, long-term monitoring and landscape analysis will be needed.

• 한국해양학회지
• /
• v.18 no.2
• /
• pp.142-148
• /
• 1983

In order to understand the circulation dynamics of the Keum River estuary, an extensive study was conducted; (i) variability of salinity boundary layer (ii) fluid dynamic characteristics (iii) tides and tidal currents (iv) circulation, diffusion, and dispersion (v) numerical modelling. As first part of this series of work, the salinity data obtained at six sites by using instantaneous profil]ing technique were analyzed in detail. it is found that the amplitude of salinity variation increases toward the upstream direction and its magnitude is greater at neap tide than spring tide. And also duration of salinity boundary layer is much longer during the neap tide than the spring tide, As a result of this study, the Keum River estuary is classified as a typical standing wave type estuary. Finally, we present a schematic diagram for the duration of the salinity boundary layer, which will be useful for further study on flocculation phenomena and sedimentation dynamics.

• 한국지구과학회:학술대회논문집
• /
• 2010.04a
• /
• pp.120-120
• /
• 2010

두 개의 별로 구성되었을 것이라고 여겨진 공생별은 밝기변화는 궤도운동에 따라 밝기가 변하는 것으로 알려졌다. 분광 관측 자료에는 이러한 궤도 변화 외에도 다양한 요소가 밝기 변화에 관여하는 것이 특성으로 나타난다. 또한 공생별은 밝기가 급격하게 증가하고 혹은 감소하기도 하는데, 이는 폭발에 기인하는 것으로 판단된다. 이러한 변화, 궤도 운동에 따라 기하학적 변화와 폭발 현상을 모두 볼 수 있는 대표적인 공생별이 Z And이다. 우리는 선행연구(MIKOLAJEWSKA & KENYON, 1996)에서 발표한 저분산 분광 자료를 이용하여 위상별로 변하는 상대적 선세기 변화를 조사하였다. MIKOLAJEWSKA & KENYON (1996)의 자료는 저분산 기기로(${\Delta\lambda\sim}3{\AA}$), HeI, HII, [OIII]5007, [NeV]등이 관측되었는데, 이러한 선들의 세기를 광이온 모델을 이용하여 예측한 후, 공생별 가스를 이온화시킨 중심별(WD)의 물리적 특성을 연구하였다. 또한 Hyung & Aller가 2002년 8월 12일 Lick Observatory에서 Hamilton Echelle Spectrograph (HES)를 사용하여 3600초 노출 관측한 고 분산 분광자료(${\Delta\lambda\sim}0.1{\AA}$)도 분석하였다. HES 관측 자료는 공생별의 위상이 $\Phi$=0.22이며, HES자료는 $3470{\AA}-9775{\AA}$에서 HI, HII, HeI, HeII, NII, NIII, OII, [OI], [OII], [OIII] 등이 있었다. 이 선들의 선 윤곽을 IRAF와 StarLink/Dipso를 이용하여 분석하고, 각 성분이 위상($\Phi$=0.22)인 상태에서의 관측자에 대해 어떠한 기하학적인 구조를 가지고 있는지 연구하였다. CLOUDY를 사용하여 광 이온 모형성운을 만들어 화학원소 및 성운가스의 물리적 조건을 연구하였다. Z And의 수소의 수밀도($N_H$)는 $10^{8.5}/cm^3$으로 가정하였다. 중심별 온도는 약 110,000K, 광도는 태양의 2000배로 추정되었다.

• Journal of The Korean Astronomical Society
• /
• v.14 no.2
• /
• pp.55-71
• /
• 1981

On the basis of observational constraints, particularly the relationship between metal abundance and cumulative stellar mass, a simple two-zone disk-halo model for the chemical evolution of our Galaxy was investigated, assuming different chemical processes in the disk and halo and the infall rates of the halo gas defined by the halo evolution. The main results of the present model calculations are: (i) The halo formation requires more than 80% of the initial galactic mass and it takes a period of $2{\sim}3{\times}10^9$ yrs. (ii) The halo evolution is divided into two phases, a fast collapse phase ($t=2{\sim}3{\times}10^8$ yrs) during which period most of the halo stars $({\sim}95%)$ are formed and a later slow collapse phase which is characterized by the chemical enrichment due to the inflow of external matter to the halo. (iii) The disk evolution is also divided into two phases, an active disk formation phase with a time-dependent initial mass function (IMF) up to $t{\approx}6{\times}10^9$ yrs and a later steady slow formation phase with a constant IMF. It is found that at the very early time $t{\approx}5{\times}10^8$ yrs, the metal abundance in the disk is rapidly increased to ${\sim}1/3$ of the present value but the total stellar mass only to ${\sim}10%$ of the present value, finally reaching about 80% of the present values toward the end of the active formation phase.

• The Journal of the Petrological Society of Korea
• /
• v.28 no.4
• /
• pp.319-345
• /
• 2019

Recently planification and effort for management, assessment and discovery of geological heritagesare being increasingly demanded with institutional strategies such as geopark, as their preservation is asked socially. In this study, we discovered geological heritages in the Jeolla Province and then performed assessment of the value and grading of them and finally suggested a promising and suitable site for the National Geopark. A total of 325 geological heritages are listed on literature review and then detailed description in field and assessment of the value for selected 158 geoheritages are completed. The assessment items are categorized into intrinsic value, subsidiary value, and preservation/management part. The intrinsic value is subdivided into scientific/educational value, composed of representativeness, rarity, geodiversity, typicality, reproducibility, and particularity, and geomorphological/landscape value composed of scale, naturality (integrity), scenery (aesthetic value). Also, subsidiary value consist of 7 subsections of soil function, ecological function, tourism value, geological resource, historical value, folk tale or legend and symbolic value, and accessibility, convenient facility (infrastructure), management condition (legal protection) is evaluated in preservation/management part. The heritages in the Jeolla Province subdivided into three types: 73 geological heritages, 42 geomorphological heritages, and 42 composite heritages. Based on points acquired in intrinsic value, all geological heritages are graded Class-I to -V. As a result, numbers of geoheritage belong to Class-I (protection at world level), -II (protection at national level), -III (nationdesignated management), -IV (involved management list), -V (candidate management list) are 12, 39, 52, 34, 21, respectively. Finally, we construct database based on Arc-GIS with all informations for each geological heritage and suggest three promising and suitable sites, 'Jirisan-Seomjingang Area' and 'south coast area of Jeolla Province', for the National Geopark.