• Korean Journal of Environment and Ecology
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• v.37 no.1
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• pp.1-12
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• 2023

We analyzed the distribution area of debris slopes in Mudeungsan (Mt. Mudeung) National Park by comparing aerial photos of the past (1966) and the present (2017) and identified the vegetation characteristics that affect the change in the area of the debris slopes by investigating the vegetation status of the debris slopes and the surrounding areas. The area of debris slopes in Mt. Mudeung appears to have been reduced to a quarter of what it used to be. Debris slopes here have decreased at an average rate of 2.3 ha/yr over 51 years by vegetation covers. Notably, most of the small-area debris slopes in the low-inclination slopes disappeared due to active vegetation coverage. However, there are still west-facing, south-west-facing, south-facing, and large-area debris slopes remaining because the sun's radiant heat rapidly raises the surface temperature of rock blocks and dries moisture, making tree growth unfavorable. Because of these locational characteristics, the small-scale vegetation in the middle of Deoksan Stony Slope, which is the broadest area, showed distinct characteristics from the adjacent forest areas. Sunny places and tree species with excellent drying resistance were observed frequently in Deoksan Stony Slope. However, tree species with high hygropreference that grow well in valleys with good soil conditions also prevailed. In some of these places, the soil layer has been well developed due to the accumulation of fine materials and organic matter between the crevices of the rock blocks, which is likely to have provided favorable conditions for such tree species to settle and grow. At the top of Mt. Mudeung, on the other hand, the forest covered the debris slopes, where Mongolian oaks (Quercus mongolica) and royal azaleas (Rhododendron schlippenbachii), which typically grow in the highlands, prevailed. This area was considered favorable for the development of vegetation for the highlands because the density of rock blocks was lower than in Deoksan Stony Slope, and the soil was exposed. Moreover, ash trees (Fraxinus rhynchophylla) and Korean maple trees (Acer pseudosieboldianum) that commonly appear in the valley areas were dominant here. It is probably due to the increased moisture content in the soil, which resulted from creating a depressive landform with a concave shape that is easy to collect rainwater as rock blocks in some areas fell and piled up in the lower region. In conclusion, the area, density of the rock blocks, and distribution pattern of rock block slopes would have affected the vegetation development and species composition in the debris slope landform.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.435-445
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• 2023

A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.

• Clean Technology
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• v.29 no.4
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• pp.272-278
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• 2023

There is a lot of interest in methods for pollutants using adsorption, and recent research is being conducted to show that biochar can be used to remove organic and inorganic pollutants. In particular, wood waste as waste biomass requires a biomass recycling method, and a method to increase the adsorption capacity of biochar produced using wood waste is needed. Biochar is created by Hydrothermal carbonization (HTC) using, which uses low temperature and high pressure, has low energy consumption and does not require moisture removal pretreatment, and biochar is created through chemical activation using KOH, NaOH, and ZnCl₂ chemicals. The adsorption characteristics of biochar were determined by analyzing iodine adsorptivity, specific surface area, pore diameter, pore volume, pore distribution, and SEM according to the activation. The results of analyzing the selecting biochar by activating the biochar produced at HTC 300℃, 4 hr by KOH, NaOH, and ZnCl₂ chemicals, the specific surface area was 774~1.387 m²/g, showing a high specific surface area similar to activated carbon, and it was confirmed that micropores with an average pore diameter in the range of 21~24 Å were formed. As a result of SEM observation, the surface was uniform with a certain shape depending on activation. It was confirmed that one pore was developed and the number of pores increased.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.49-60
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• 2021

The Geumhwa Au-Ag deposit is located within the Cretaceous Gyeongsang basin. Mineral paragenesis can be divided into two stages (stage I and II) by major tectonic fracturing. Stage II is economically barren. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages(early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early substage, marked by deposition of pyrite with minor wolframite; middle substage, characterized by introduction of electrum and base-metal sulfides with Cu-As and/or Cu-Sb sulfosalts; late substage, marked by hematite and Bi-sulfosalts with secondary minerals. Changes in vein mineralogy reflect decreases in temperature and sulfur fugacity with a concomitant increase in oxygen fugacity. Fluid inclusion data indicate progressive decreases in temperature and salinity within each substage with increasing paragenetic time. During the early portion of stage I, high-temperature (≥410℃), high-salinity fluids (up to ≈44 equiv. wt. % NaCl) formed by condensation during decompression of a magmatic vapor phase. During waning of early substage, high-temperature, high-salinity fluids gave way to progressively cooler, more dilute fluids associated with main Au-Ag mineralization (middle) and finally to ≈180℃ and ≥0.7 equiv. wt. % NaCl fluids associated with hematite and sulfosalts (± secondary) mineralization (late substage). These trends are interpreted to indicate progressive mixing of high- and medium to low-salinity hydrothermal fluids with cooler, more dilute, oxidizing meteoric waters. The Geumhwa Au-Ag deposit may represent a vein-type system transitional between porphyry-type and epithermal-type.

• Journal of Korean Society of Forest Science
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• v.112 no.1
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• pp.71-82
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• 2023

Forest biomass is used as a representative indicator of forest size, maturity, and productivity. Therefore, quantitative evaluation is important for management and harvest as well as the evaluation of ecosystem functions and services including CO₂ absorption. The allometric equation is a widely used method for estimating the value of each component through the relative growth rate of plants. Recently, studies indicated that the relative growth of trees is changing because of the increased CO₂ concentration in the atmosphere and the resulting climate change, raising the need to review the previously developed relative growth models and coefficients. In this study, the height-diameter at breast height (DBH) relationships of four major tree species in Korea [(Pinus densiflora (PD), Larix kaempferi (LK), Quercus variabilis (QV), and Quercus mongolica (QM)] were analyzed using the 5th-7th National Forest Inventory (NFI) data. Furthermore, these results were compared with the present yield table from the National Institute for Forest Science. This analysis revealed that the expected height for the same DBH increased as the NFI progressed. For example, in model analysis, the expected heights for PD, LK, QV, and QM for DBH of 25 cm were 12.48, 19.17, 14.47, and 13.19 m, respectively, in the 5th NFI data. In the 7th NFI data, these values were estimated as 13.61 (+9.1%), 21.58 (+12.7%), 15.76 (+8.9%), and 13.93 m (+5.6%), respectively. These results indicate that the major tree species in South Korean forests currently are more vigorous in height growth than in diameter growth when compared to the height-DBH development trends by tree species identified through past survey data.

• Informatization Policy
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• v.18 no.1
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• pp.73-99
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• 2011

The Korean military has developed and operated computer, network, communication technologies as well as war game models to strengthen the national defense M&S continuously. In particular, lots of projects for developing models for drill/training, analyses, and acquired fields are being conducted in the military. However, it needs to look into the actual conditions and seek for strategies to develop the national defense M&S. First of all, in the field of war games, various national defense architectures have been built, including war and information environment architectures starting from the resource architecture in 2006. However, the function of drill and training is limited, so additional war game architectures are required to be built. To build joint war game architectures available as an effective verification tool to implement plans of the national defense and war architectures, this study examines the actual conditions of the current war game systems and suggested building joint war game architectures.

• The Journal of the Korea Contents Association
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• v.17 no.1
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• pp.662-672
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• 2017

Recently, with the development of mobile devices and near field communication, mobile P2P networks have been actively studied to improve the limits of the existing centralized processing system. A peer has limited components such as batteries, memory and storage spaces in mobile P2P networks. The trust of a peer should be discriminated in order to share reliable contents in mobile P2P networks. In this paper, we propose a trust discrimination scheme considering limited resources in mobile P2P environments. The proposed scheme discriminates the trust of a peer by direct rating values using the rating information of the peer and indirect rating values by the other peers. The recent update time is included in the rating information. The proposed scheme reduces the redundant rating information by comparing the recent update times of the rating information. It is shown through performance evaluation that the proposed scheme reduces the number of messages and improves the accuracy of trust over the existing scheme.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.695-700
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• 2005

In the sensor network, a lot of sensor nodes are scattered sparsely and organizes a united communication network between each node. After that, environmental information around each sensor node are gathered and analyzed. Because each node operates under resource constraint, the efficiency and hardware specification of a node should be maximized. There exist technical constraints until now but recent technical progress in IC fabrication and wireless network enables to construct a tiny embedded system, which has the properties of low cost, low power consumption, multi functions. Wireless sensor network becomes a modern research field with technical improvements, is studied in numerous laboratories, and is called as diverse different project names - Wireless Integrated Network Sensors (WINS), Mobile Ad hoc NETwork (MANET), Ubiquitous Sensor Network (USN). TinyOS is one of leading project and is widely used. In this paper, we suggest a sensor network, which uses TinyOS platforms and aims for context awareness in a home environment.

• Korean Journal of Childcare and Education
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• v.10 no.4
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• pp.71-95
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• 2014

The paper explored the limitations of anecdotal records in kindergarten and presented the challenges toward authentic records. The data was collected from 7 teachers working at private kindergartens through focus group interviews (FGI) and individual follow-up interviews. The participants' conversation in the FGI and their responses in the individual interviews were analyzed according to the principles of thematic coding. The participants described the barriers from recording a child anecdote in private kindergarten and at the same time their voices implied the possibilities to overcome the difficulties. All descriptions of the participants were converged on the 3 themes with rhetoric of "from A to B". For becoming anecdotal records in kindergarten, in summary, the records at the present should be changed 1) "from formal and faithless documentation to fluent resources of children's development", 2) "from disconnectedness between the records and curriculum to recursive circulation for improving pedagogical realities", and 3) "from canned documentation written by a struggling teacher to meaningful writing produced by a teacher like researcher".

• Journal of the Korean Home Economics Association
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• v.33 no.2
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• pp.57-71
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• 1995

가족형태가 부의 자녀양육시간과 결정요인에 미치는 영향 기혼여성의 취업증가로 인해 아버지의 적극적인 자녀양육 참여가 요구되어 왔다. 또한 이 같은 요구는 부의 참여가 기혼여성, 자녀의 성장발달등 가정천체에 미치는 영향이 중요하다는 인식과 함께, 부의 자녀양육시간 연구는 중요한 사회적 관심사로 동시에 연구대상으로 대두되었다. 이같은 변화속에서, 실제 가정생활에서 부의 자녀양육시간은 개개인에 따라 큰 차이를 나타냄에 따라, 어떤 개인적, 가정적, 또는 사회인구적 요인들이 양육시간량을 결정하는가를 연구하는 것은 그 의미가 있다. 현대가정의 또 하나의 커다란 변화는 미혼부 증가, 이혼증가로 인한 편부의 증가, 재혼 증가로 인한 계부의 증가 등 가족형태의 다양화에 있다. 본 연구에서는 이 같은 변화를 반영하여, 각기 다른 가정형태에서의 부의 자녀양육 참여시간을 비료 분석하였다, 또한 부의 자녀양육 시간량 관련요인을 조사하기 위하여 노동시장의 근로시간, 개별적 인적 자원, 역할관념, 가정환경등의 효과를 검증하였다. 본 연구에서 사용된 자료는 미국 위스콘신대학내 (University of Wisconsin-Madison), 인구 및 생태센터 (Center for Demography and Ecology)에서 1988년에 실시한 설문조사 및 면접조사로써, "전국 가족 및 공도거주체 조사" (National Survey of Family and Households)에서 추출했다. 연구결과에 따르면, 가족형태가 부의 자녀양육시간에 미치는 효과는 큰 것으로 검증 되었다. 각 그룹간 비교에서 편부가정의 부는 여타의 가정내의 부보다 많은 시간을 자녀와 놀아주고, 야외활동 및 과제물 도와주기 등에 할애한 것으로 나타났다. 반면 계부는 여타의 가정내의 부보다 더욱 적은 시간을 자녀와 함께 하였다. 부의 자녀양육시간 결정요인 분석 결과에 따르면, 직장에서의 노동 시간, 교육수준, 자녀 연령이 큰 효과를 나타내는 것으로 밝혀졌다,, 부의 직장 근로시간이 적을수록 교육수준이 높을수록 자녀양육 참여시간은 높은 것으로 나타났다. 또한 어린자녀를 가진 아버지일수록 자녀와 함께하는 시간이 긴 것으로 나타났다. 것으로 나타났다.