• 한국약용작물학회지
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• 제27권5호
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• pp.322-329
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• 2019

Background: Studies have suggested that the northern provinces of Gangwon-do are good sites for licorice (Glycyrrhiza uralensis Fisch.) cultivation in Korea, as they have similar temperatures to its original locations in northern China. However, poor growth and freezing injury are often reported in Korea. Therefore, it is necessary to reassess the domestic cultivation site of licorice. Methods and Results: To determine the optimum temperature for cultivating licorice, the growth, yield, and pharmacological characteristics of G. uralensis were assessed in a temperature gradient tunnel at Eumseong, Chungcheongbuk-do, Korea in 2017. Plant height increased until the temperature rose to $5.9^{\circ}C$ above the local external temperature. Yield (㎏/10a) increased by 46.9% when the growing temperature was $1.5^{\circ}C$ to $3.0^{\circ}C$ (T2) above the external temperature and by 72.6% when the growing temperature was $3.0^{\circ}C-4.5^{\circ}C$ (T3) above the external temperature. However, a difference of $4.5^{\circ}C-5.9^{\circ}C$ (T4) above the external temperature, decreased the yield by 9.8% compared to that at T2. The glycyrrhizin content of G. uralensis roots in each temperature band was 0.72%, 0.53%, 0.91%, and 0.84% (T1, T2, T3, T4), these differences appear to result form individual plant variation rather than growth temperature. Conclusions: Based on the results of this study, we estimate that the temperature-based optimum cultivation site for G. uralensis in Korea is the south central region, rather than the northern province of Gangwon-do. Improvement in growth and yield maybe observed if the plantations in the central Jecheon (Chungcheongbuk-do, Korea) are expanded into the south central region.

• 한국습지학회지
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• 제19권2호
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• pp.202-210
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• 2017

전단응력은 여러 분야에서 사용하는 매우 중요한 역학 인자 중 하나이며, 인공수로의 설계를 위해서 중요하다. 현재 전단응력은 과거에 정해진 계산법을 사용하고 있지만, 사용되는 식에서 바닥전단응력과 에너지경사와 같이 실제로 측정하거나 계산하기 어려운 요소들이 존재한다. 특히, 에너지경사는 산정하기 매우 어려운 인자이며, 전단응력분포를 구하기위해서는 에너지경사가 있어야만 산정할 수 있지만, 경계층의 유속기울기와 유속을 측정하는 것은 현실적으로 어려운 부분이다. 또한 전단응력분포 중 바닥전단응력은 직접 측정하기 매우 어렵고, 유속에 비해 연구가 다소 더딘 실정이다. 전단응력분포를 정확하게 산정할 수 있다면, 바닥전단응력과 에너지경사를 손쉽게 산정할 수 있다. 본 연구에서는 에너지경사를 반영하지 않고 엔트로피 M을 이용하여 평균유속과 전단응력분포를 간단히 산정하는 연구를 진행하였고, 적용한 식의 효용성을 증명하기 위해 기존의 실험실 실측 자료를 사용하였다. 이는 그래프를 통해 응력분포를 나타내어 비교분석을 하였으며, 등류와 부등류에서 각각 결정계수는 0.930-0.998까지로 거의 일치하였다.

• 한국ITS학회 논문지
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• 제17권6호
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• pp.121-132
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• 2018

기상은 교통흐름, 운전자의 주행패턴, 교통사고 등 여러 방면에서 도로교통에 영향을 미치는 중요한 요인이다. 본 연구는 기상상황과 노면상태 사이의 관계에 초점을 맞추어 기계학습을 통해 도로의 노면상태를 추정하는 모델을 개발하였다. 노면 상태의 수집을 위해 실험 차량에 노면센서를 부착하여 '건조', '습윤', '젖음', 3가지 범주로 구분된 노면상태 정보를 수집하였고, 이를 추정하기 위한 변수로 도로의 기하구조 정보(곡률, 구배), 교통정보(교통량), 기상정보(강우량, 습도, 온도, 풍속)를 활용하였다. 노면 상태를 예측하기 위한 알고리즘으로는 다양한 기계학습 알고리즘이 검토되었으며, 그 중 가장 높은 정확도를 보인 'Random forest'를 기반으로 한 2단계 분류모형을 구축하였다. 총 16일의 실측 데이터 중 14일의 데이터를 모델을 학습하는 데 활용하였고, 2일의 데이터를 모형의 정확도를 검증하기 위해 사용하였다. 그 결과 81.74%의 검증 정확도를 가지는 노면상태 예측 모델을 구축하였다. 본 연구의 결과는 기상청에서 관측하는 기상정보로 도로의 노면상태를 추정할 수 있다는 가능성을 보여주며, 새로운 장비나 센서를 설치하지 않고도 기존의 기상 관측 정보와 교통정보 등을 활용하여 노면의 상태를 추정할 수 있음을 시사한다.

• 대한토목학회논문집
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• 제29권1A호
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• pp.9-18
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• 2009

본 논문은 외부 긴장된 텐던의 장력추정에 대한 차분진화기법의 적용을 소개한다. 제안된 차분진화 알고리즘의 SI기법은 기존의 구배 기반의 최적화 기법과는 다르게 전역해 탐색이 가능하다. 수치실험은 인식변수에 대한 사전정보 없이도, 제안된 차분진화기법이 외부긴장 텐던의 정확한 장력 추정뿐 아니라 유효공칭직경 추정이 가능하여 1%미만의 추정 오차를 갖는 유용한 기법임을 보여준다. 또한 긴장력 손실 유무의 사용 상태를 고려한 축소실험 모델 실험을 이용하여 제안된 기법의 타당성이 실험적으로 검증되었다. 실험의 결과는 긴장력 손실과 무관하게 정확한 장력 추정과 유효공칭직경의 추정뿐 아니라 실험 모델의 감쇠비까지 추정되어 제안된 기법이 적합하고, 효과적인 방법임을 보여준다. 유효공칭 직경의 2% 추정 오차는 실제 꼬여진 단면을 갖는 텐던의 직경과 충실단면을 갖는 FE 모델의 직경의 차이 때문이다. 마지막으로, 기존이론과의 비교 분석으로 제안된 차분진화 기법의 정확성과 우월성이 검증되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2961-2966
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• 2007

When the pressure at the weak spot established at a certain part of a high pressure vessel or piping system exceeds a design pressure, this weak spot is burst, and the pressurized gas emitted through the weak spot will cause a compression wave system. In this connection, in the present study, an experimental study by using a conventional shock tube facility is performed to estimate the effects of the material of diaphragm, curvature radius and thickness of materials on the valve opening time in diaphragm. Pressure sensor having 500kHz in natural frequency is installed at 35mm downstream of the rupture diaphragm to measure the static pressure history of propagating and being accumulated compression wave. 4 kinds of materials are used as diaphragm that is aluminium, copper, stainless steel and zinc. The diaphragm radii of curvature R are ${\infty}$, 120mm and 60, respectively. And the depth for $90^{\circ}$ groove is 0.04mm. It is found that the smaller the tensile strength and elongation of the rupture diaphragm is, the smaller the radius of curvature of the rupture diaphragm is, and for the same conditions the thinner the thickness of the rupture diaphragm is, the shorter the valve opening time becomes. Also, the tensile strength, elongation and the radius of curvature of the rupture diaphragm for the same conditions are smaller, the maximum pressure rise caused by the coalescences of the compression wave is smaller. Finally the pressure ratio is higher, the valve opening time is shortened and gradient of pressure increment is more steepen.

• Journal of Forest and Environmental Science
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• 제28권4호
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• pp.199-204
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• 2012

This study was conducted to estimate climax index by eco-morphology for major 36 tree and sub-tree species in natural deciduous forests so as to interpret seral position of each species in the forest community. Fourteen eco-morphological characters which were considered to be associated with successional gradient in the forest were selected for the study. Four levels per character for each species were given on a standardized scale of increasing climax, and the index was computed by the proportion of the sum of total scores, expressed by percent values. With calculated mean value of 54.8 for all indices, Carpinus cordata had the highest index value of 90.5, and Populus davidiana recorded the lowest of 13.2. The most climax group, greater than 70 of the index, contained only 8 species, intermediate group, between 41 to 70 of the index, had 23 species, and the most pioneer group, less than 40 of the index comprised 5 species. The result has noticed that the large number of species would take advantage of most diverse resource and niche in the intermediate stage of the sere in the forest. By cluster analysis all 36 species were subjected to be classified into several species groups which had common similar eco-morphological characteristics. The indices were additionally plotted on the two dimensional graph to recognize the positions related to the light absorption factor and reproduction factor. The climax index of tree and sub-tree species developed by this study could be applied to understand the present status of successional stage on the basis of species composition by the method of summing up the indices. And comparison of forest successional stage among various forest communities could be done by summing up the climax indices of composed species in each community. However, this kind of applied methodology should be limited to the forest of similar species composition and site condition.

• Mass Spectrometry Letters
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• 제2권4호
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• pp.92-95
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• 2011

Pyrophosphates are the key intermediates in the biosynthesis of isoprenoids, and their concentrations could reveal the benefits of statins in cardiovascular diseases. Quantitative analysis of five pyrophosphates, including isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP), farnesyl pyrophosphate (FPP), and geranylgeranyl pyrophosphate (GGPP), was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in negative ionization mode. After dilution with methanol, samples were separated on a 3 ${\mu}m$ particle multi-modal $C_{18}$ column ($50{\times}2$ mm) and quantified within 10 min. The gradient elution consists of 10 mM ammonium bicarbonate and 0.5% triethylamine (TEA) in water and 0.1% TEA in 80% acetonitrile was used at the flow rate of 0.4 mL/min. Overall recoveries were 51.4-106.6%, while the limit of quantification was 0.05 ${\mu}g$/mL for GPP and FPP and 0.1 ${\mu}g$/mL for IPP, DMAPP, and GGPP. The precision (% CV) and accuracy (% bias) of the assay were 1.9-12.3% and 89.6-111.8%, respectively, in 0.05-10 ${\mu}g$/mL calibration ranges ($R^2$ > 0.993). The devised LC-MS/MS technique with the multi-modal $C_{18}$ column can be used to estimate the biological activity of pyrophosphates in plasma and may be applicable to cardiovascular events with cholesterol metabolism as well as the drug efficacy of statins.

• 한국해양학회지
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• 제30권6호
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• pp.543-549
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• 1995

연속된 AVHRR/SST 자료를 이용한 표층유속의 추정에 역행렬법이 이용되어 왔다. 본 모델에서 방정식체계는 열방정식과 제한요소로서 가중치가 있는 발산최소화이다. 제한요소는 열방정식의 속도해중에서 null space(Menke, 1984)에 해당하는 해를 구하기 위하여 도입되었으며 이 식들은 격자화한 영역에서 AVHRR/SST의 수온경사에 의해 선형화된다. 실험은 열방정식에 대한 발산최소화의 상대적 중요성을 나타내는 가중치의 크기를 설정하기 위하여 수행하였으며 행렬식은 SVD(Singular Value Decomposion)에 의해 해를 구했다. 실험에서 가상온도분포의 수온경사와 가상유속장의 발산의 크기는 실제해역에 근사시켰다. 열방정식은 착산의 효과를 무시하고 열속이 공간적으로 일정한 것으로 가정하여 구성하였으며 이와같은 가정에 의한 오류를 고려하기 위하여 가상 온도자료에 무작위오류를 도입하였다. 실험결과에 의하면 가중치를 설정하는 기준으로서 상대오차 최소화가 잔차최소화보다 바람직한 것으로 나타났으며 가중치가 $10^{-1}$의 크기일 때 추정유속의 오류가 가장 작은것으로 나타났다.

• 한국환경과학회지
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• 제7권4호
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• pp.425-432
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• 1998

The purpose of the present study is to estimate the release of dissolved Inorganic nitrogen and photophorous from sediments of Deukryang Bay. One method used In this study is to calculate nutrients released from a concentration gradient between sediment porewaters and the overlying water based on periments. The calculated and measured ammonium released from the sediments were 8.93mg-atN/$m^2$ hr and 60.4mg/atN/$m^2$ hr, respectively In July. 8.57mg-atN/$m^2$. hr and 32.9mg/atN/$m^2$ hr, respectively in October. The ammonium was released more highly in truly than in October, and the measured ammonium flux was higher than the calculated one. The calculated nitrate plus nitrite released from the sediments were 0.31mg/atN/$m^2$. hr in July and 0.84mg/atN/$m^2$. hr in October. The measured nitrate plus nitrite released from the sediments was 282mg/atN/$m^2$. hr in October. The calcuated was lower than the measured because the content of the nutrients in the sediments was always much more than in the overlying waters, and it has shown a differently seasonal pattern compared to the ammonium flux. The calculated phosphorous released from the sediments were 0.97mP/atN/$m^2$ hr and measured negative fluxed -6.50mP/atN/$m^3$ hr In truly, and alculated 0.18mg/atP/$m^2$. hr and measured 24.6mg/atP/$m^2$. hr, respectively in October.

• 한국산업융합학회 논문집
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• 제23권3호
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• pp.433-444
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• 2020

This study proposes a method to improve the sleep stage and efficiency estimation of sleep apnea patients using a UWB (Ultra-Wideband) radar. Motion and respiration extracted from the radar signal were used. Respiratory signal disturbances by motion artifacts and irregular respiration patterns of sleep apnea patients are compensated for in the preprocessing stage. Preprocessing calculates the standard deviation of the respiration signal for a shift window of 15 seconds to estimate thresholds for compensation and applies it to the breathing signal. The method for estimating the sleep stage is based on the difference in amplitude of two kinds of smoothed respirations signals. In smoothing, the window size is set to 10 seconds and 34 seconds, respectively. The estimated feature was processed by the k-nearest neighbor classifier and the feature filtering model to discriminate between the sleep periods of the rapid eye movement (REM) and non-rapid eye movement (NREM). The feature filtering model reflects the characteristics of the REM sleep that occur continuously and the characteristics that mainly occur in the latter part of this stage. The sleep efficiency is estimated by using the sleep onset time and motion events. Sleep onset time uses estimated features from the gradient changes of the breathing signal. A motion event was applied based on the estimated energy change in the UWB signal. Sleep efficiency and sleep stage accuracy were assessed with polysomnography. The average sleep efficiency and sleep stage accuracy were estimated respectively to be about 96.3% and 88.8% in 18 sleep apnea subjects.