• Geomechanics and Engineering
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• v.30 no.6
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• pp.517-524
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• 2022

Every year, millions of waste tires are discarded across the world. Storage of waste tires presents many problems such as fire threats, epidemics, and non-economic factors. Furthermore, the disintegration process of waste tires is not economical or practical due to its time-consuming, and disposal requirements. In this study, half-section waste tires (HSWTs) were integrated with high-density polyethylene (HDPE) pipes under different relative density conditions. The main aim of the study was to reduce the deformation values of embedded HDPE pipes in sandy soil and to evaluate the soil-pipe interaction. In comprehensive laboratory tests, half-section waste tires were integrated in two different ways: in the middle of the pipeline and along the pipeline. Accordingly, it was concluded that the effectiveness of waste tires reduces the deformation and bending moment values in the critical regions of pipes. As a result of reinforcement in the mid-point of the pipe defined as the most critical region, 52% and 36% less deformation was observed in the crown and springlines of the pipe, respectively. In addition, the bending moment values for the same critical section were determined to be 40% less in the crown and 28% less in the springline regions of the pipe.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.66.1-66.1
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• 2021

Extinction curves observed toward individual Active Galactic Nuclei (AGN) usually show a steep rise toward Far-Ultraviolet (FUV) wavelengths and can be described by the Small Magellanic Cloud (SMC)-like dust model. This feature suggests the dominance of small dust grains of size a < 0.1 ㎛ in the local environment of AGN, but the origin of such small grains is unclear. In this paper, we aim to explain this observed feature by applying the RAdiative Torque Disruption (RATD) to model the extinction of AGN radiation from FUV to Mid-Infrared (MIR) wavelengths. We find that in the intense radiation field of AGN, large composite grains of size a > 0.1 ㎛ are significantly disrupted to smaller sizes by RATD up to dRATD > 100 pc in the polar direction and dRATD ~ 10 pc in the torus region. Consequently, optical-MIR extinction decreases, whereas FUV-near-Ultraviolet extinction increases, producing a steep far-UV rise extinction curve. The resulting total-to selective visual extinction ratio thus significantly drops to RV < 3.1 with decreasing distances to AGN center due to the enhancement of small grains. The dependence of RV with the efficiency of RATD will help us to study the dust properties in the AGN environment via photometric observations. In addition, we suggest that the combination of the strength between RATD and other dust destruction mechanisms that are responsible for destroying very small grains of a <0.05 ㎛ is the key for explaining the dichotomy observed "SMC" and "gray" extinction curve toward many AGN.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.496-498
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• 2021

In Korea, based on the high fertility rate before 1980, the total population has been steadily increasing, and since the mid-1980s, the fertility rate has fallen sharply and has fallen below the level of population replacement. The cause of low birth rate in the region is not voluntary rejection, but rather, it is necessary to find out the cause by identifying the structural causes of the local community from various angles. We collected local Internet news and local representative cafe data, where many mothers participate, based on the budget area with a very low fertility rate among various areas. Factors of childbirth inhibition were analyzed by using the frequency of concurrent words that became issues related to population decline, low birthrate, and child-rearing welfare.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.49.2-49.2
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• 2019

We present results from our long-term observing campaign, using the NASA IRTF at Maunakea, to obtain 2 - 4 ㎛ spectra of 118 red point sources in the line of sight to the Galactic Center (GC). Our sample is largely composed of point sources selected from near- and mid-infrared photometry, but also includes a number of massive young stellar objects. Many of these sources show high foreground extinction as shown by deep 3.4 ㎛ aliphatic hydrocarbon absorption feature, which is a characteristic of the diffuse ISM and comes from the long line of sight through the diffuse medium toward the Central Molecular Zone (CMZ), the central 300 pc region of the GC. The deep 3.1 ㎛ H₂O ice absorption band coming from the local, dense material in the GC CMZ suggests that most sources are likely located in the GC CMZ. A few of these sources show weak CCH₃OH ice absorption at 3.535 ㎛, which can provide a strong constraint on the CCH₃OH ice formation in the unique environment of the CMZ. From the best-fitting models, the optical depths of these features are determined and used to generate a well-rounded view of the ice composition across the GC CMZ and the spectral characteristics of massive YSOs in the GC.

• Journal of Korean Society of Rural Planning
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• v.29 no.1
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• pp.1-10
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• 2023

This study aims to establish a landscape plan that can preserve the identity of the region while meeting the unique functions related to land use of the Saemangeum agricultural land. In addition, it was intended to prepare a mid- to long-term landscape plan basic concept for the formation and management of the Saemangeum agricultural land landscape. Therefore, in this study, landscape management by type for processing/storage facilities, production/processing facilities, complex/sales facilities, and research/experimental facilities for facilities scheduled to move in after setting the direction and five strategies for landscape management considering the specificity of agricultural land direction was set. In addition, the landscape management direction for 6 common landscape elements such as buildings, open spaces, advertisements, colors, public facilities, and night scenery was also presented. In particular, Agroworks, Agro City, and Agro Town, which are important landscape areas, are landscape-focused management areas, and the landscape management direction for the area has been established. This study is considered to have great utility value when setting landscape standards for public or private buildings and infrastructure, development projects, etc. to be moved in prior to establishing a landscape plan for agricultural land. It is expected that it can be used as a basis for deliberation and review of the landscape standards derived from this study in the future landscape-related licensing for agricultural land.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.736-737
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• 2015

In these days, international construction market including construction companies has much grown due to globalization and economic boom in the mid 2000's. The size of international construction market, measured with overseas revenue of 225 construction firms, has expanded 2.7 times from 2003 to 2008 according to the ENR. However, after the global financial crisis of 2008 it has faced condition of low growth. In this research, major changes of international construction market and top contractors have been studied. In this study, changes of international construction market have been analyzed in the aspect of region and product including general buildings, transportation, petroleum, etc. Then, in order to find the changes of top contractors which obtained good accomplishment, business performance of companies have been examined by the compound annual growth rate, profit margin and international revenue by comparing the data before 2008 and after. The purpose of the study is to understand major changes of international construction market. Also, strategy changes of top contractors against market stagnation, profit depreciation, high competition have been inferred through the study. The result of the study would contribute to analyzing the strategies of construction companies in international market.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.3
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• pp.30-41
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• 2023

Aviation turbulence, caused by atmospheric eddies, is a disruptive phenomenon that leads to abrupt aircraft movements during flight. To minimize the damages caused by such aviation turbulence, the Aviation Meteorological Office provides turbulence information through the Korea aviation Turbulence Guidance (KTG) and the Global-Korean aviation Turbulence Guidance (GKTG). In this study, we evaluated the performance of the KTG and GKTG models by comparing the in-situ EDR observation data and the generated aviation turbulence prediction data collected from the mid-level Korean Peninsula region from January 2019 to December 2021. Through objective validation, we confirmed the level of prediction performance and proposed improvement measures based on it. As a result of the improvements, the KTG model showed minimal difference in performance before and after the changes, while the GKTG model exhibited an increase of TSS after the improvements.

• Animal Systematics, Evolution and Diversity
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• v.40 no.1
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• pp.21-34
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• 2024

Two arenicolus halacarid species, Actacarus ornatus n. sp. and A. pacificus Bartsch, 1979, are recorded from sandy intertidal sediment along the coast of South Korea. Actacarus ornatus n. sp. closely resembles A. karoensis Abé, 1990, recorded from Japan, in having chaetotaxy of the idiosoma, legs, palps of gnathosoma, and perigenital setae in both males and females. However, it differs from A. karoensis by a slightly convex tectum, the presence of a row of foveae on the mid-ventral surfaces of the anterior epimeral plate and genitoanal plate, and the absence of areolae on both the anterior and posterior dorsal plates as well as microplatelets on the membranous cuticle alongside the anterior and posterior dorsal plates. Actacarus pacificus Bartsch, 1979, which is widely distributed in the Indo-Pacific region, is characterized by separated plates, a truncated tectum, the anterior epimeral plate with four pairs of setae, the posterior epimeral plate with one dorsal and two ventral setae, and three pairs of subgenital setae in males. A comparative analysis of the morphological characteristics of A. pacificus was conducted within regional populations, including the Korean population. Moreover, a key to Actacarus species from the northwestern Pacific, including a new species, is provided. The genus Actacarus is reported for the first time from Korea.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.3
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• pp.67-74
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• 2024

In the context of rapid temperature rise in mid-to-high latitude regions, cold region wetlands have become a hotspot for current wetland carbon cycle research due to their high sensitivity to climate change. Strengthening the monitoring of CO₂ fluxes in wetland ecosystems is of great practical significance for clarifying the carbon balance of wetlands and maintaining the ecological balance of wetland ecosystems in China's high latitude regions. In this study, the carbon flux (NEE, Net ecosystem exchange; GPP, Gross Primary Production; RECO, Ecosystem response) of Jingxin Wetland was monitored by eddy correlation method from August 2021 to March 2024.2022-2023 shows CO₂ sinks, absorbing 349.4 g C·m^-2·yr^-1 annually. The correlation analysis showed that Ta, VPD and PPFD were the main environmental factors affecting CO₂ flux in Jingxin wetland.

• International Journal of Industrial Entomology and Biomaterials
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• v.48 no.4
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• pp.225-232
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• 2024

Sarasaeschna pryeri Martin, 1909 (Aeshnidae, Odonata), which is distributed in Japan and the Republic of Korea is a rare species that has been found exclusively on Jeju Island in the Republic of Korea. Even though more information has been required to better understand the ecology of the species, research on this species has been limited mainly due to local distribution and rarity. Following recent observation on its occurrence in the Korean peninsula areas, this study evidenced the inhabitation of S. pryeri in the mid-eastern region of Korean peninsula in Gangwon Province in the Republic of Korea. In detail, throughout two years' field investigation, adults and nymphs were detected in four Korean peninsula locations, such as Yachon-ri, Jukwang-myeon; Haesang-ri, Ganseong-eup; Gajin-ri, Jukwang-myeon; and Unbong-ri, Toseong-myeon in Goseong-gun in Gangwon Province. Moreover, observations of ecological behavior, in particular for oviposition activities, confirms the inhabitation of S. pryeri in Gangwon Province. In order to substantiate species status, we provided the description of adult and nymph morphology, and molecular identification. The ecological and behavioral information obtained in this study can serve as crucial foundational data for the understanding the ecology of dragonflies in the Korean Peninsula and contribute to the conservation management to preserve biodiversity.