• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.415-420
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• 2017

유량자료는 연속적으로 관측하기가 쉽지 않을 뿐 아니라 모든 관측소에서 매년 적정한 유량자료를 생산하는 것 또한 매우 어려운 실정이다. 이에 따라 미계측 유역에 대한 유량 산정을 위해 많은 연구가 진행되고 있다. 영국의 "Low Flow Studies report(Institute of Hydrology, 1980)"에서는 갈수량 산정과 관련하여 기저유량비(Base Flow Index, BFI)를 사용하는 것을 추천하였다. 국내에서는 이와 관련한 적용 사례가 없기 때문에 본 연구에서는 BFI를 적용하여 미계측 유역의 갈수량을 산정하고자 하였다. 대상유역은 낙동강 권역의 22개 지점을 대상으로 실시하였으며, 기저유량비 및 평균 갈수량과 유역 및 수문인자들의 상관분석을 수행하였다. 분석을 통하여 기저유량비는 토양군 C와 지하수위를 독립변수로, 평균 갈수량은 기저유량비, 유역면적, 강수량을 독립변수로 선정하여 회귀분석을 실시하였다. 그 결과 개발한 기저유량비 지역회귀모형의 상대오차는 -26.5%(기계2)~57.2%(구영)의 범위로 분포하였고, 절대오차의 평균은 17.2%로 산정되었다. 평균 갈수량 지역회귀모형은 상대오차가 -38.4%(도천)~184.4%(길안)의 범위에서 분포하고 있으며, 절대오차의 평균은 47.3%이다. 그러나 소토, 기계2, 길안 지점을 제외하면 절대오차는 30.6%이다. 상대오차는 다소 부정적이지만 기존에 개발된 지역회귀모형으로 평균 갈수량을 산정한 결과와 비교하면 상대적으로 양호한 것으로 판단된다. 사용한 자료의 기간이 6년으로 통계적인 결과로 보기에는 다소 미흡한 측면이 있지만, 유역인자로서 BFI가 미계측 유역의 갈수량 특성을 설명할 수 있는 우수한 인자라고 판단하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.355-355
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• 2022

기후변화에 의한 이상가뭄 발생 등을 대비하기 위한 비상용수 또는 대체수자원으로서의 지하수 개발수요가 증가하는 추세에 따라 기저유량 확보 및 수질 개선 방안을 수립하는 것은 지속가능한 수자원 이용·관리 측면에 있어서 매우 중요하다. 지하수 및 기저유량 확보 및 수질 개선을 위해서는 지표-지하수 통합 관리가 필요하며 이를 기반으로 지하수 및 기저유량 변동에 대한 인과관계 파악 및 구체적인 조사가 필요하다. 따라서 본 연구에서는 지표-지하수에 대한 계절적·시공간적 변동성을 잘 모의할 수 있는 통합 모델을 기반으로 지하수위 변동을 포함한 물수지 분석과 장·단기 유출해석이 정량적으로 분석하고자 하였으며, 평창군 대화면, 만대지구, 신둔천 유역을 대상으로 간벌, BMP, LID를 비롯한 다양한 시나리오에 따른 기저유량 및 수질변화 그리고 오염특성 파악을 수행하였다. 본 연구에서는 지표-지하수 통합 모델링을 위하여 SWAT-MODFLOW 모형을 활용하였으며, 간벌 시나리오의 경우 모형 Source code를 수정하여 간벌의 효과를 모의할 수 있도록 수정하였다. 또한 BMP와 LID의 경우 각 HRU별로 저감시설에 대한 효율 및 매개변수 조정을 통해 효율을 모의하였다. 모형의 입력자료 구축을 위하여 지표 모형의 경우 DEM, 토지이용도, 토양도를 활용하였으며, 지하수 모형의 경우 지하수기초조사자료에 수록된 수리전도도, 비산출율, 비보유율 조사결과를 활용하여 입력자료를 구축하였다. 그 결과 간벌시나리오의 경우 건기시 최소 6.7% 이상의 하천유량, 22.56% 이상의 기저유량, 그리고 0.3 m 이상의 지하수위 확보가 가능한 것으로 나타났다. BMP의 경우 유역면적의 약 7%에 BMP가 설치된 것으로 나타났으며, 이에 따른 하천 말단 SS저감효율은 6.7%로 나타났으나 유량에서는 큰 차이를 나타내지 못하였다. 마지막으로 LID시나리오의 경우 적용 소유역의 강우시 평균유량이 약 29% 감소하였으며 건기시 평균 기저유량이 약 44%이상, 평균 BFI는 약 0.13 증가한 것으로 나타났다.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.1-11
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• 2014

This study was conducted to investigate the changes understory vegetation composition (shrub and herb layers) in Mt. Gyebang as a northern-temperate deciduous broadleaf forest. Tracheophytes were 146 taxa, consisting 56 families, 93 genera, 124 species, 17 varieties, 3 forma, 2 sub-species and 1 unknown taxa in research subject area. As species area curve analysis, herbaceous layer and shrub species have been decreased over time. As a result of Mantel-test, basal area of upper layer affects to understory vegetation change (p<0.0001). Mean importance value was dominated Lindera obtusiloba (21.585%), Rhododendron schlippenbachii (19.774%) in the shrub layer, identified Sasa borealis (14.082%) and Lindera obtusiloba (7.921%) in the herb layer. According to NMS analysis of shrub layer, Species characterized by strong correlation have been reduced as time goes by. And it reports different species as an increasing in basal area of the upper layer. Herb layer plots of the NMS analysis, Rhododendron schlippenbachii and Rhododendron mucronulatum consistently were affected in shrub layer. In consequence of MRPP-test for changes in vegetation composition, It was analyzed that there are no significant differences for vegetation composition changes on shrub layer in 5-10 years. As a changes of vegetation composition on herb layer were analyzed significantly, composition change of herb layer species was larger than shrub layer species in understory vegetation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.2 s.344
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• pp.84-95
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• 2006

In H/W implementation for the finite field the use of normal basis has several advantages, especially, the optimal normal basis is the most efficient to H/W implementation in $GF(2^m)$. In this paper, we propose a new, simpler, parallel multiplier over $GF(2^m)$ having a Gaussian normal basis of type k, which performs multiplication over $GF(2^m)$ in the extension field $GF(2^{mk})$ containing a type-I optimal normal basis. For k=2,4,6 the time and area complexity of the proposed multiplier is the same as tha of the best known Reyhani-Masoleh and Hasan multiplier.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.132-144
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• 2017

현재, 빛을 이용한 화학 연구가 활발히 진행되고 있고 이러한 연구는 양자역학을 기반으로 화학에서 상당히 중요한 부분을 차지하고 있다. 또한 컴퓨터의 발전에 따라 여러 계산 모델들이 개발되고 있다. 본 논문에서는 회전파 근사(Rotating Wave Approximation, RWA)를 통해 라비 진동을 이론적으로 확인하고, 가장 간단한 연속파 레이저와 두 에너지 준위에서 시작하여 레이저 펄스와 두 에너지 준위, 레이저 펄스와 이원자분자인 $Na_2$ 분자의 두 전자에너지 퍼텐셜 준위, 그리고 실제 시간 밀도 범함수 이론(Real-Time Time Dependent Density Functional Theory, RT-TDDFT)이란 제일원리계산을 통해 연속파 레이저와 $H_2$ 분자와 $C_2H_4$ 분자에서까지 관찰하였다. 이 연구를 통해 공명 전이의 경우 펄스의 면적이 ${\pi}$의 홀수 배일 때 완전한 입자수 전이가 일어나는 펄스 면적 정리를 확인할 수 있었고, 이원자분자인 $Na_2$의 경우엔 펄스의 지속시간도 입자수 전이에 영향을 미친다는 것을 확인하였다. 더 나아가 $H_2$ 분자와 $C_2H_4$ 분자에서는 RT-TDDFT 계산을 통해 라비 진동을 확인할 수 있었고, 두 종류의 기저함수간의 대조를 통해 기저함수 선택의 중요성을 알아보았고, 가장 중요하게는 레이저를 잘 조작하면 입자를 원하는 상태로 들뜨게 할 수 있다는 것이란 결론을 얻게 되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1297-1308
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• 2006

Multiplications in finite fields are one of the most important arithmetic operations for implementations of elliptic curve cryptographic systems. In this paper, we propose a new multiplication algorithm and VLSI architecture over $GF(2^m)$ using Gaussian normal basis. The proposed algorithm is designed by using a symmetric property of normal elements multiplication and transforming coefficients of normal elements. The proposed multiplication algorithm is applicable to all the five recommended fields $GF(2^m)$ for elliptic curve cryptosystems by NIST and IEEE 1363, where $m\in${163, 233, 283, 409, 571}. A new VLSI architecture based on the proposed multiplication algorithm is faster or requires less hardware resources compared with previously proposed normal basis multipliers over $GF(2^m)$. In addition, we gives an easy method finding a basic multiplication matrix of normal elements.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.12
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• pp.80-86
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• 2003

Elliptic curve cryptosystem(ECC) offers the highest security per bit among the known publick key system. The benefit of smaller key size makes ECC particularly attractive for embedded applications since its implementation requires less memory and processing power. In this paper, we propose a new multiplier structure with configurable output sizes and operation cycles. The number of output bits can be freely chosen in the new architecture with the performance-area trade-off depending on the application. Using the architecture, a 193-bit normal basis multiplier and inversion unit are designed in GF(2$^{m}$ ). It is implemented using HDL and 0.35${\mu}{\textrm}{m}$ CMOS technology and the operation is verified by simulation.

• Tuberculosis and Respiratory Diseases
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• v.54 no.2
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• pp.191-198
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• 2003

Background : The pathological features in asthmatic airway remodeling are diverse. The aim of this study was to examine the degree of airway vascularity in relation to the other remodeling parameters in asthmatics. Methods : Bronchial biopsies were done in 34 asthmatic patients, and 6 control subjects. The basement membrane thickness and the subepithelial thickness were measured in the hematoxylin-eosin stained tissue, and the degree of vascularity was measured using type IV collagen immunostaining. Results : 1) Compared to the control subjects, the asthmatics showed a significant increase in the basement membrane thickness ($6.92{\pm}2.01{\mu}m$ vs $9.67{\pm}2.84{\mu}m$, p<0.05) and the subepithelial thickness ($44.49{\pm}31.92{\mu}m$ vs $121.22{\pm}72.79{\mu}m$, p<0.05). 2) Compared to the control subjects, the asthmatics showed a significant increase in the vascular area per unit submucosal area ($4.51{\pm}2.13%$ vs $10.32{\pm}6.08%$, p<0.05). In addition, the number of vessels per unit submucosal area showed an increased tendency without statistical significance. 3) In the asthmatics, the number of vessels and the vascular area per unit submucosal area showed no correlation with the basement membrane thickness, the subepithelial thickness, the severity, the forced expiratory volume in 1 second($FEV_1$), and the methacholine provocative concentration 20($PC_{20}$). Conclusion : This study showed that vascularity was an important parameter in asthmatic airway remodeling but it was not related to the other remodeling parameters such as the basement membrane thickness and the subepithelial thickness. Each of these asthmatic remodeling parameters may have a different clinical significance. Therefore, further studies will be needed.

• Korean Journal of Environment and Ecology
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• v.16 no.2
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• pp.172-178
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• 2002

This study quantified $CO_2$, SO$_2$and NO$_2$uptake by vegetation for the Namsan Nature Park in Seoul, and explored values for the park to contribute to atmospheric purification. Broad-leaved forest accounted for about 54% of total forest area, and tree-age structure was dominated by a young, growing tree population. Tree density and basal area averaged 17.5 trees/100$m^2$ and 2,580$\textrm{cm}^2$/100$m^2$, respectively. Atmospheric purification per unit area by forest type and age class was greater in older age classes, associated with changes in basal area, and tended to be greater in broad-leaved or mixed forest than in coniferous forest for the same age classes. Mean $CO_2$storage per unit area for all the forest types and age classes was 293.8 t/ha and economic value of the $CO_2$storage was ￦ 147millions/ha. Annual uptake averaged 24.6t/ha/yr for $CO_2$, 17.1 kg/ha/yr for SO$_2$and 43.9 kg/ha/yr for NO$_2$, and economic value of the annual uptake was ￦ 13millions/ha/yr. Total forest area stored 72,100 t of $CO_2$, and annually sequestered 6,040 t/yr of $CO_2$, 4,200 kg/yr of SO$_2$and 10,770 kg/yr of NO$_2$. Economic value of atmospheric purification for the entire area amounted to approximately ￦ 36,100millions for the $CO_2$storage, and ￦ 3,100millions/yr for the annual $CO_2$, SO$_2$ and NO$_2$uptake. The park played an important role through annually offsetting $CO_2$emissions from fossil fuel consumption by 1,100 persons, SO$_2$emissions by 2,800 persons, and NO$_2$ emissions by 1,160 persons. The results from this study are expected to be useful not merely in informing the public of atmospheric purification values of urban nature parks, but in urging the necessity for replanting and management budgets.

• Korean Journal of Environment and Ecology
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• v.17 no.4
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• pp.337-345
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• 2004

The objective of this study was to monitor vegetation recovery process after timber harvesting at (Mt.) Baekwoonsan Seoul National University Forests, Korea. Two monitoring plots were established in 1994 and woody plant were monitored in 1997, 1999, 2001, and 2003. Vegetation development pattern during last ten years (1994-2003) after timber harvesting were as follows; Styrax obassia, Styrax japonica and Lindera erythrocarpa as of the existing tree were competitive species in the first year after clear-cut, Styrax japonica and Lindera erythrocarpa as of sprout tree and Aralia elata as of seedling were dominant species in the sixth year after clear-cut, and Lindera erythrocarpa, Styrax japonica and Quercus serrata were dominant species from the eighth year to the tenth year after clear-cut. Species diversity index of harvested forest interior was decreased at the southwestern slope while it was increased in the northeastern slope till 6th year and decreased after the 8th year). According to DBH distribution pattern, No. of individuals of Quercus serrata, Styrax japonica and Lindera erythrocarpa showed high frequency in the southwestern slope, and Acer pseudosieboldianum, Styrax obassia, Magnolia sieboldii, Lindera erythrocarpa, and Aralia elata showed good growth in the northeastern slope. There was a difference between slopes in Basal area. It was decreased at the southwestern slopes during the 10th year continuously and it was increased the sixth year however, was decreased after the eighth year at the northeastern slope.