• 천문학회지
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• 제48권1호
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• pp.57-66
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• 2015

Monte-Carlo radiative models of the diffuse Galactic light (DGL) in our Galaxy are calculated using the dust radiative transfer code MoCafe, which is three-dimensional and takes full account of multiple scattering. The code is recently updated to use a fast voxel traversal algorithm, which has dramatically increased the computing speed. The radiative transfer models are calculated with the generally accepted dust scale-height of 0.1 kpc. The stellar scale-heights are assumed to be 0.1 or 0.35 kpc, appropriate for far-ultraviolet (FUV) and optical wavelengths, respectively. The face-on optical depth, measured perpendicular to the Galactic plane, is also varied from 0.2 to 0.6, suitable to the optical to FUV wavelengths, respectively. We find that the DGL at high Galactic latitudes is mostly due to backward or large-angle scattering of starlight originating from the local stars within a radial distance of r < 0.5 kpc from the Earth. On the other hand, the DGL measured in the Galactic plane is mostly due to stars at a distance range that corresponds to an optical depth of $${\sim_\sim}$$ 1 measured from the Earth. Therefore, the low-latitude DGL at the FUV wavelength band would be mostly caused by the stars located at a distance of $r{\leq}0.5$ kpc and the optical DGL near the Galactic plane mainly originates from stars within a distance range of $1{\leq}r{\leq}2kpc$. We also calculate the radiative transfer models in a clumpy two-phase medium. The clumpy two-phase models provide lower intensities at high Galactic latitudes compared to the uniform density models, because of the lower effective optical depth in clumpy media. However, no significant difference in the intensity at the Galactic plane is found.

• 대기
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• 제20권3호
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• pp.307-318
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• 2010

This study investigates the generation and movement of low-concentration $CO_2$ observed in Gosan during summer from 2002 to 2006. For analysis, additional $CO_2$ data in Anmyeondo, Ryori, Barrow, and Minamitorishima as well as NOAA/ESRL daily global $CO_2$ fields, background trajectories data, and 850 hPa wind fields are also used. Based on analyses using various observed data, we classified three types of low-concentration $CO_2$ in Gosan according to its origin: i) the origin of the Siberian continental, in which the consumption of $CO_2$ is active due to photosynthesis from broad forests, ii) the origin of Okhotsh and Artic seas, in which the low-concentration $CO_2$ is dominant due to high primary productivity by a plankton bloom, and iii) the origin of the Northwestern Pacific which is related to the entry of air mass from high latitudes. These results show that the low-concentration $CO_2$ observed in Gosan during summer is not originated from the Pacific oceans as known in previous studies, but originated from high latitude regions such as the Siberian continental and the Okhotsh and Artic seas.

• 한국측량학회지
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• 제28권4호
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• pp.413-420
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• 2010

현재 전리층 지연은 GNSS 측량의 가장 큰 오차이다. 단일 주파수 수신기 사용자는 전리층 지연을 모델링 하거나 보정하기 위하여 전리층 보정 알고리즘을 적용해야 한다. 실시간 보정이 가능한 전리층 모델로는 항법메시지로 제공되는 GPS의 Klobuchar 모델과 Galileo의 NeQuick 모델이 있다. 이 연구에서는 두 모델의 효용성을 계절과 위도에 따라 평가하였다. 첫 번째 검증으로, 각 계절별로 수원 GPS 상시관측소 상공의 연직방향 총전자수를 산출하였다. 두 번째 검증으로는 위도가 서로 다른 3개 상시관측소(철원, 수원, 제주)에서의 VTEC을 계산해 관측소 위도와의 상관성을 분석하였다. 산출된 총전자수는 전지구 전리층 모델인 GIM 모델과 IRI 모델에서 제공하는 총전자수와 비교하였다. 그리고 GIM 모델과 IRI 모델을 기준으로 Klobuchar 모델과 NeQuick 모델의 RMS 차이를 각각 산출하였다. 그 결과, 계절과 관측소 위도와 무관하게 NeQuick 모델의 RMS 차이가 Klobuchar 모델의 RMS 차이보다 약 0.01~3.50 TECU 낮게 나타났다.

• Journal of Astronomy and Space Sciences
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• 제34권1호
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• pp.55-65
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• 2017

We studied the hour-lines of six extant Yangcheon-cheoks in Korea. To find whether Yangcheon-cheok was used in the whole area of Korea, we calculated the length of shadows of Yangcheon-cheok on the Korean Peninsula, Nanjing and Beijing as well as Hanyang (Seoul), according to 24 solar terms. Comparing the length of shadows with hour-lines of those relics, we could find that Yangcheon-cheok was suitable for use at limited times (from 9:00 to 15:00) during the year. Also, this sundial is more appropriate for use at low latitudes than high ones. Among existing relics, that of Seoul Museum of History made with porcelain was much more suitable to use at Hanyang and its higher latitude. Lee's collection was also suitable to use at Nanjing. It is certain that Yangcheon-cheok was a portable sundial which could be used from nine to fifteen of clock all the year around except for the winter season.

• 천문학회보
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• 제35권1호
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• pp.83.1-83.1
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• 2010

In the last meeting of KAS, we reported the first statistical study of Faraday rotation measure (RM) in the large-scale structure of the universe using the data of cosmological structure formation simulations. With a turbulence dynamo model for the intergalactic magnetic field (IGMF), we predicted that the root mean square of RM through filaments is \sim 1 rad/m^2. Future radio observatories such as the Square Kilometer Array (SKA) could detect this signal level. However, it is known that the typical foreground galactic RM is a few tens and less than ten rad/m^2 in the low and high galactic latitudes, respectively. So the RM in the large-scale structure could be detected only after the foreground galactic RM is removed. In this talk, we show how we remove the foreground galactic RM and what we obtain from the masked data, by using some noise models and masking techniques. Our results can be used to simulate future RM observations by SKA, and eventually to constrain the origin and evolution of the IGMF in the large-scale structure.

• 한국산림과학회지
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• 제108권1호
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• pp.133-137
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• 2019

하늘다람쥐의 형태적 특성을 파악하기 위해 강원도 원주시 백운산에서 2014년 4월부터 2016년 3월까지 하늘다람쥐의 6가지 외부형태적 특성에 대한 측정을 실시하고 분석하였다. 그 결과 하늘다람쥐는 암컷이 수컷보다 큰 암컷편향적 성적이형성을 나타내는 것으로 확인되었다. 이는 단독 생활을 하고 암컷 혼자 새끼를 키우는 하늘다람쥐의 번식전략과 관련이 있는 것으로 보인다. 국내와 핀란드, 일본에서 파악된 하늘다람쥐의 외부형태 측정치 중 체중과 머리-몸통의 길이를 비교한 결과, 모두 핀란드와 일본 그리고 한국 순서대로 위도가 높은 지역이 크게 나타났다. 이러한 형태적 특성의 차이는 분포 지역 위도에 따른 기후와 서식환경 차이에 따른 것으로 생각되며, 추후 체중과 머리-몸통의 길이 이외의 외부형태 측정치에 대한 비교 연구가 필요할 것으로 생각된다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권1호
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• pp.42-42
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• 2004

Recently, Pi2 pulsations during the intervals of extremely quiet magnetospheric conditions (Kp = 0$\^$+/) have been reported by Sutcliffe and Lyons (2002). The authors observed several Pi2 bursts occurred simultaneously at high (magnetic latitude = 71$^{\circ}$) and low (42$^{\circ}$) latitudes during the absence of magnetospheric substorms and found that the bursts are strongly correlated with poleward boundary intensifications (PBIs), associated with enhancements of energetic ion fluxes observed by the Geotail satellite at Xgsm - -12 Re to -17 Re and Ygsm - 12 Re to 10 Re in the plasma sheet. (omitted)

• The Korean Journal of Ecology
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• 제18권1호
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• pp.99-108
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• 1995

Deciduous hardwood communities were ecologically analyzed in order to determine their distributional characteristics. The quadrats were sampled in Mt. Chiri, Mt. Deokyu, Mt. Kyeryong, Mt. Sokri, and Mt. Jungwang, and their environmental factors including topographical features as well as soil properties were investigated. The computer program TWINSPAN and CANOCO were used to elucidate the relationship between environmental factors and species composition. In the relations of communities and environmental factors, the optimal ecological habitats of Carpinus tschonoskii community could be the sites at low latitudes such as the regions of southern part of Korea in which total nitrogen and organic matters are rich, while those of Fraxinus mandshurica community, Acer mono community, and Betula costata community could be the sites which are wet and have high total nitrogen and organic matters in soil. The quercus mongolica community is distributed widely throughout Korea, and its ecological habitats could be the sites which have high soil nutrient and moderate soil moisture in central and northern parts of Korea, while those of Quercus variabilis community could be the sites which is dry and have high Mg and C.E.C. value.

• Ocean and Polar Research
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• 제33권spc3호
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• pp.349-358
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• 2011

In order to ascertain latitudinal variation of lipid contents and compositions in copepods, we collected warm water copepod species (Euchaeta sp. and Pleuromamma spp.) from four different regions from low (sub-tropical) to mid (temperate) latitudes in the Northwest Pacific Ocean. Total lipid contents of Pleuromamma spp. were about 11 $ug{\cdot}ind^{-1}$ with little latitudinal variation, whereas Euchaeta sp. showed slightly higher lipid content (20 $ug{\cdot}ind^{-1}$) than Pleuromamma spp. with latitudinal gradient (low at subtropic and high at temperate). Wax esters, known as the major storage lipid classes, were found to be the dominant lipid classes (accounting for more than 35% of total lipids) in Euchaeta sp., whereas in Pleuromamma spp., phospholipids, known as cellular membrane components, were the dominant lipid classes. However, the exception was specimens from warm pool region exhibiting dominance in storage of lipids as a form of triacylglycerols. Among fatty acids, polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA : 22:6(n-3)) (about 35% of total fatty acids), were most abundant in Euchaeta sp., while saturated fatty acids (SAFA), specially hexadecanoic acid (16:0) (about 30% of total fatty acids), were most abundant in Pleuromamma spp.. Among the neutral fraction of lipids, phytol, originated from the side chain of chlorophyll, was found in all samples which generally indicate active copepods feeding on algae. While only trace amounts of short-chain fatty alcohols were found in Pleuromamma spp., significant amounts of fatty alcohols were found in Euchaeta sp.. Particularly, significant amounts of long chain monounsaturated fatty alcohols (20:1 and 22:1), generally found in cold water species, were found in Euchaeta sp. from low latitudes. The latitudinal variation of trophic lipid markers in these copepods could be significantly related with in-situ food availability and species-specific diet preference. The result of this study suggests that the lipid contents and compositions in copepods may not only indicate their nutritional condition and feeding ecology but also provide insight into species-specific living strategies under different environmental conditions (i.e. water temperature, food availability).

• International Journal of Industrial Entomology and Biomaterials
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• 제48권1호
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• pp.48-58
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• 2024

Reports of a global decline in pollinator populations, especially mason bees, have raised concerns regarding the maintenance of pollination interactions. Although addressing local factors causing bee decline is a potential mitigation strategy at the landscape scale, regional rates and high-latitude threats to bee diversity are unclear. We investigated the distribution of mason bees (Osmia. spp. (O. pedicornis, O. corniforns, O. taurus, and O. satoi) and measured species richness and species ratios at regional, latitudinal, and altitudinal scales. We examined the association between bee species richness and three putative environmental conditions: high-low, altitude-dependent, and latitude-dependent. The species richness of the O. pedicornis bee was the highest and it was found between latitudes 35° and 37°, and at 500-600 m in both the northern and southern hemispheres, showing an inverse latitudinal gradient of bee species richness in South Korea. Mason bee species richness and global climate are important predictors of flowering plant diversity. Climate change threatens bee and vascular plant diversity; however, the overlap between bee abundance and plant diversity can be improved by employing suitable conservation strategies.