• Geomechanics and Engineering
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• 제30권4호
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• pp.373-382
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• 2022

Unsaturated soil at high suctions is widespread. Many civil engineering projects are related to the hydro-mechanical behavior of unsaturated soils at high suctions, particularly in arid and semiarid areas. To investigate water retention behaviors of nine clayey soils (one is classified as fat clay and the others are classified as lean clay according to the unified soil classification system), the high suction (3.29-286.7 MPa) was imposed on the specimens at zero net stress by the vapor equilibrium technique. In this paper, the effect of void ratio on the water retention behavior at high suction was discussed in detail. Validation data showed that soil types, i.e., different mineralogical compositions, are critical in the soil water retention behavior at a high suction range. Second, the hysteresis behavior at a high suction range is mainly related to the clay content and the specific surface area. And the mechanism of water retention and hysteresis behavior at high suctions was discussed. Moreover, the maximum suction is not a unique value, and it is crucial to determine the maximum suction value accurately, especially for the shear strength prediction at high suctions. If the soil consists of hydrophilic minerals such as montmorillonite and illite, the maximum suction will be lower than 10⁶ kPa. Finally, using the area of hysteresis to quantify the degree of hysteresis at a high suction range is proposed. There was a good correlation between the area of hydraulic hysteresis and the specific surface area.

• 한국조경학회지
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• 제30권1호
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• pp.52-60
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• 2002

This paper presents a streetscape design for "Dangiae-Gil"which is located at 126-1 Yangpyung-2dong, Yeongdeungpo-gu, Seoul and is about 500m in length and about 24m in width. The design goals are to make a green street on which people want to walk and people can walk and rest safely and pleasantly. To achieve these goals, concepts of environmentally-friendliness, placeness, safety, amenity, vitality, connectivity, and democracy are developed. For pedestrian safety, shared street concepts, such as crank, slalom etc. are adopted. The site is divided into 5 thematic spaces, such as "Village Entrance Space", "Culture Street", "Dangsan Park", "Nature Street", and "Ferry Space". The Village Entrance Space, which is an entrance of the Dangjae-Gil and a welcoming space, is for communicating information about the area. "Dangnamu"(zelkova tree) and signs are introduced here. The Culture Street is for experiencing past and present culture of the area. Colored tiles and plant boxes attached to benches are introduced. The Dangsan park is a sacred space where modem people can feel the sacredness of nature arid of being in a refuge. Dangjib, Dangnamu, multi-purpose plaza, athletic facilities, and playground for infants are introduced. The Nature Street is a space for feeling and teaming nature which has disappeared from the area leading to the river and a space for community participation. The elementary school walls were demolished and nature education spaces, such as butterfly and dragonfly garden, ecological pond, wildflower garden, etc., which are related to school education, are introduced. The Ferry Space is a space symbolizing a old ferry crossing and an entrance plaza to a bridge for "Sunyu-do\" . A boat-shaped deck, an elevator for handicap people, and parking space are introduced. In conclusion, sustainable management schemes for the site are suggested.sted.

• 농업과학연구
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• 제9권1호
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• pp.260-268
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• 1982

본연구(本硏究)는 우리나라 사유림소유자(私有林所有者)의 산림시업의식(山林施業意識)과 이에 영향(影響)을 미치는 제요인(諸要因)과의 관계(關係)를 개별적(個別的) 또는 종합적(綜合的)으로 구명(究明)하여, 임업기술지도(林業技術指導) 및 사유림시책입안(私有林施策立案)에 필요(必要)한 기초자료(基礎資料)를 제시(提示)하는데 목적(目的)을 두고 수행(修行)하였으며, 연구자료(硏究資料)는 81, 11~82, 1월(月) 사이에 179명(名)의 일반산주(一般山主)와 83명(名)의 독림가(篤林家)를 대상(對象)으로 조사(調査)하였다. 종속변수(從屬變數)로서의 산림시업의식(山林施業意識)은 Likert 형척도(型尺度)에 의하여 평점(評點)하였으며, 독립변수(獨立變數)는 연령(年令), 교육수준(敎育水準), 임야면적(林野面積), 사회경제적지위(社會經濟的地位), 전달매개수단(傳達媒介手段), 사회심리(社會心理)의 6개요인(個要因)으로서 변수간(變數間)의 상호연관성(相互聯關性)을 일반산주(一般山主), 독림가별(篤林家別)로 비교분석(比較分析) 하였다. 지금까지의 연구결과(硏究結果)를 요약(要約)하면 다음과 같다. 1. 산림시업의식(山林施業意識)의 평균점수(平均點數)는 일반산주(一般山主)가 독림가(篤林家)보다 2점(點)정도 낮았으며, 그 차이(差異)는 유의적(有意的)이었다. 한편, 독립변수(獨立變數)로서의 산주연령(山主年令), 임야면적(林野面積), 사회경제적지위(社會經濟的地位) 및 전달매개변수(傳達媒介變數)의 평균점수(平均點數)도 일반산주(一般山主)가 낮았으나, 사회심리변수(社會心理變數)만은 두 산주집단(山主集團)사이에 유의차(有意差)가 없었다. 2. 일반산주(一般山主의 산림시업의식(山林施業意識)은 연령변수(年令變數)와 매우 유의적(有意的)인 부(負)의 상관(相關)을 이루고 있었으며, 그 밖의 독립변수(獨立變數)와는 정(正)의 상관(相關)을 나타내었다. 반면(反面)에 독림가(篤林家)의 시업의식(施業意識)은 교육수준변수(敎育水準變數)와 유의적(有意的)적인 부(負)의 상관(相關)을 이루고 있었으며, 연령(年令), 전달매개(傳達媒介) 및 사회심리변수(社會心理變數)와는 정(正)의 상관(相關)을 보였다. 3. 산림시업의식(山林施業意識)과 6개독립변수간(個獨立變數間)의 중상관계수(重相關係數)는 일반산주(一般山主)가 0.6971, 독림가(篤林家)가 0.5207 로서 매우 유의적(有意的)이었다. 시업의식변량(施業意識變量)에 대한 독립변수(獨立變數)의 상대적(相對的) 영향력(影響力)은 일반산주(一般山主)의 경우 사회심리변수(社會心理變數)에 의하여 41.0%가 설명(說明)되고, 독림가(篤林家)의 경우는 사회심리변수(社會心理變數)에 의하여 16.2%, 연령변수(年令變數)에 의하여 6.0%가 설명(說明)되는 것으로 나타났다. 4. 전체산주(全體山主)의 시업의식(施業意識)에 대한 7가지 사회심리성격(社會心理性格)의 중상관계수(重相關係數)는 0.6566으로서 매우 유의적(有意的)이었으며, 이러한 7가지 성격요인(性格要因)은 통합적(統合的)으로 종속변량(從屬變量)을 43.1% 설명(說明)할 수 있다. 그리고, 이 43.1%는 다시 무의욕적성격(無意慾的性格)에 의하여 15% 전통적가정관(傳統的家庭觀)에 의하여 11.2%가 설명(說明)되는 것으로 나타났다. 5. 결국(結局) 우리나라 사유림소유자(私有林所有者)의 산림시업의식(山林施業意識)은 대부분(大部分) 경제적요인(經濟的要因) 보다는 심리적(心理的)인 요인(要因)에 의하여 결정(決定)되므로 임업지도활동(林業指導活動)을 통하여 사회심리적요인(社會心理的要因)을 개선(改善)해 나갈 필요(必要)가 있다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.65-72
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• 2001

Power system stabilizer act efficiently to damp the electromechanical oscillations in interconnected power systems. This paper presents an algorithm for the optimal parameter selection of a power system stabilizer in two-area power systems with a series HVDC link. This method is one of the classical techniques by allocating properly pole-zero positions to fit as closely as desired the ideal phase lead between the voltage reference and the generator electrical power and by changing the gain to produce a necessary damping torque over the matched frequency range. Control of HVDC converter and inverter are used a constant current loop. Proper parameters of PI controllers are obtain based on the Root-locus technique in other to have sufficient speed and stability margin to cope with charging reference values and disturbance. The small signal stability arid transient stability studies using the PSS parameters obtained from this method show that a natural oscillation frequency of the studycase system is adequately damped. Also the simulation results using the HVDC converter and inverter parameters obtained from this proposed method show proper current control characteristics. The simulation used in the paper was performed by the Power System Toolbox software program based on MATLAB.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1765-1773
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• 2016

Wastewater containing kraft lignin (KL) discharged from pulp and paper industries could cause serious environmental contamination. Appropriate effluent treatment is required to reduce the pollution. Investigations on anaerobic bacteria capable of degrading KL are beneficial to both lignin removal and biofuel regeneration from the effluent. In this paper, an anaerobic strain capable of degrading KL was isolated from the sludge of a pulp and paper mill and identified as Dysgonomonas sp. WJDL-Y1 by 16S rRNA analysis. Optimum conditions for KL degradation by strain WJDL-Y1 were obtained at initial pH of 6.8, C:N ratio of 6 and temperature of 33℃, based on statistical analyses by response surface methodology. For a 1.2 g/l KL solution, a COD removal rate of 20.7% concomitant with biomass increase of 17.6% was achieved after 4 days of incubation under the optimum conditions. After the treatment by strain WJDL-Y1, KL was modified and degraded.

• 한국대기환경학회지
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• 제15권2호
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• pp.79-87
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• 1999

$^{239+240}Pu$ concentrations in precipitation were determined for the period of May 1994 to August 1996 in oder to describe current $^{239+240}Pu$ deposition at the mid-western coat of Korea (Ansan, 37$^{\circ}$17'N, $126^{\circ}$50'E). $^{239+240}Pu$ concentration in daily precipitation varied from 0.05 to 131$\mu$Bq $kg^{-1}$ with a geometric mean of $1.26\mu$Bq $kg^{-1}$. The concentration was high in the period of Yellow Sand Storm in spring and low in wet summer monsoon. The specific $^{239+240}Pu$ concentration in daily precipitation appears to be controlled by the $^{239+240}Pu$ input to the atmosphere in spring and washout effects by precipitation in the wet summer monsoon. Wet depositional flux of $^{239+240}Pu$ varied from 4 to 123$\mu$Bq $m^{-2}d^{-1}$ with a geometric mean of $33.8\mu$Bq $m^{-2}d^{-1}$ and with a maximum in the period of Yellow Sand Storm and a minimum in the period of wet summer monsoon. $^{238}Pu$/$^{239+240}Pu$ activity raios(0.04~0.31) in precipitation for March-June period suggested that one of the major sources of Pu isotopes falling in Ansan area is the arid region of the Chinese continent.

• 한국조경학회지
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• 제29권5호
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• pp.51-59
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• 2001

This paper presents a design of the Dasan Children\`s Park which is located Shindang- dong, lung-gu, Seoul which has an area of about 3,678$m^2$. Objectives for the design were to make nature-friendly space, learning space, interesting play space, space for every child, adventure play space, traditional play space, sense of place, and recycle space. For the space compositions a children\`s garden, a traditional play space, and a science play space were located around the S shaped main route. Facilities relating nature, science, culture. environment and adventure play were arranged in the 3 main spaces. The Children\`s Garden is a green space for learning and playing with natural elements. It is composed of a ecological learning space, a children\`s story garden, a children\`s song road, an environmental labyrinth, and a pall space leer handicap children. The Science Play Place is a place space for learning scientific theories through plays to which scientific theories were applied. It is composed of a total play structure, a math experience playground, a \"Keojunggi\" play space, a sound reflecting experience space, arid an infant playground. The Traditional Play Madang(space) is a space for traditional plays. It is composed of a traditional play pattern, a sun dial, and a floor fountain. The Recycle Road is a dragon shaped road fort learning about resource recycling and conservation. It is composed of a dragon head, body, tail space and a dragon bead(cint mani).int mani).

• 한국세라믹학회지
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• 제42권7호
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• pp.469-474
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• 2005

Activated Carbon Fibers (ACFs) are widely used as adsorbents in technologies related to pollution abatement due to their highly porous structure and large adsorption capacity. The porous structure and surface area of ACFs depends strongly on both the activation processes arid the nature .of the precursors. The chemical activation with hydroxides has recently been, of great interest as it permits the preparation of activated carbon fibers with highly developed porosity. In this work, OXI-PAN fiber used as precursor for the preparation of activated carbon fibers by chemical activation with KOH and NaOH. The affects of several activation conditions on the surface properties, pore size distribution and adsorption capacity of Ag ion and Iodine ion on ACFs studied.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.224-227
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• 2008

Land cover and its changes, affecting multiple aspects of the environmental system such as energy balance, biogeochemical cycles, hydrological cycles and the climate system, are regarded as critical elements in global change studies. Especially in arid and semiarid regions, the observation of ecosystem that is sensitive to climate change can improve an understanding of the relationships between climate and ecosystem dynamics. The purpose of this research is analyzing the ecosystem surrounding the Gobi desert in North Asia quantitatively as well as qualitatively more concretely. We used Normalized Difference Vegetation Index (NDVI) derived from SPOT-VEGETATION (VGT) sensor during 1999${\sim}$2007. Ecosystem monitoring of this area is necessary because it is a hot spot in global environment change. This study will allow predicting areas, which are prone to the rapid environmental change. Eight classes were classified and compare with MODerate resolution Imaging Spectrometer (MODIS) global land cover. The time-series analysis was carried out for these 8 classes. Class-1 and -2 have least amplitude variation with low NDVI as barren areas, while other vegetated classes increase in May and decrease in October (maximum value occurs in July and August). Although the several classes have the similar features of NDVI time-series, we detected a slight difference of inter-annual variation among these classes.

• 한국콘텐츠학회논문지
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• 제2권4호
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• pp.85-92
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• 2002

본 논문에서는 고속 ATM 스위치에 적합한 셀 스케줄링 알고리즘을 제안하고 있다. 제안한 셀 스케줄링 방식은 기존의 FRR(Fixed weight Round Robin: 고정 가중치 라운드 로빈) 방식과 QLT(Queue Length Threshold) 변형방을 결합한 가변 가중치 라운드 로빈(VRR: Variable weight Round Robin) 셀 스케줄링 방식이다. FRR 방식은 각 버퍼별로 고정 가중치를 부여하여 고정 라운드 로빈 방식에 의해 셀 스케줄링을 수행하므로 고속 스위치의 구현 관점에서는 매우 큰 장점을 지니고 있지만 ATM 서비스 클래스들이 요구하는 QoS를 만족시키거나 네트워크 상황에 융통성 있게 대처할 수는 없으므로 VRR 방식은 FRR 방식을 기반으로 고정 가중치를 수행하고 버퍼 상황에 따라 가변 가중치로 확장하는 방식을 적용하여 셀 손실 QoS를 향상시키면서 셀 지연률 QoS를 만족시킬 수 있는 방식임을 시뮬레이션을 통하여 입증하였다.