• Korean Journal of Biological Psychiatry
• /
• v.28 no.1
• /
• pp.13-22
• /
• 2021

Objectives Despite growing attention to anxiety in bipolar disorder (BD), little research has assessed anxiety symptoms in the course of BD. The current prospective follow-up study examines the influence of subjectively and objectively measured anxiety symptoms on the course of BD. Methods A total of 49 patients with BD were followed-up prospectively for average of one year at an average of four months interval. The Korean version of the Beck Anxiety Inventory (K-BAI), the Hamilton Anxiety Rating Scale, heart rate variability (HRV) were used to measure anxiety subjectively, objectively and physiologically. Participants were divided into high and low anxiety groups based on their K-BAI scores. Kaplan-Meier survival analysis was performed to compare the recurrence of mood episode, suicide attempt, emergency room visit, and psychiatric hospitalization between two groups. Mediators were investigated with Cox proportional hazards models. Results Compared to the low anxiety group, the high anxiety group reported significantly higher impulsiveness (p = 0.016) and lower high frequency component on HRV (p = 0.007) after controlling for severity of BD. Regarding survival analysis, the high anxiety group showed hastened depressive episode recurrence (p = 0.048) and suicidal ideation was the mediator of the hazard ratio (HR) 1.089 (p = 0.029) in the Cox model. Moreover, the high anxiety group showed a tendency of accelerated suicide attempt (p = 0.12) and impulsivity was the risk factor of suicide attempt (HR = 1.089, p = 0.036). Conclusions This interim analysis of prospective study suggests that high anxiety level in BD may anticipate unfavorable course. Further studies are needed to understand the multifactorial mechanism of anxious bipolar patients.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.116-116
• /
• 2021

자연 하천에서의 부유사 농도 계측은 주로 재래식 채집방식을 활용한 직접계측 방식에 의존하여 비용과 시간이 많이 소요되며 점 계측 방식으로 고해상도의 시공간 자료를 측정하기엔 한계가 존재한다. 이러한 한계점을 극복하기 위해 최근 위성영상과 드론을 활용하여 촬영된 다분광 혹은 초분광 영상을 통해 고해상도의 부유사 농도 시공간분포를 측정하는 기법에 대한 연구가 활발히 진행되고 있다. 하지만, 다른 하천 물리량 계측에 비해 부유사 계측 연구는 하천에 따라 부유사가 비균질적으로 분포하여 원격탐사를 통해 정확하고 전역적인 농도 분포를 재현하기는 어려운 실정이다. 이러한 부유사의 비균질성은 부유사의 입도분포, 광물특성, 침강성 등이 하천에서 다양하게 분포하기 때문이며 이로 인해 부유사는 지역별로 다양한 분광특성을 가지게 된다. 따라서, 본 연구에서는 이러한 영향을 고려한 전역적인 부유사 농도 예측 모형을 개발하기 위해 실내 실험을 통해 부유사 특성별 고유 분광 라이브러리를 구축하고 실규모 수로에서 다양한 부유사 조건에 대한 초분광 스펙트럼과 부유사 농도를 측정하는 실험을 수행하였다. 실제 부유사 농도는 광학 기반 센서인 LISST-200X와 샘플링을 통한 실험실 분석을 통해 계측되었으며, 초분광 스펙트럼 자료는 초분광 카메라를 통해 촬영한 영상에서 부유사 계측 지점에 대한 픽셀의 스펙트럼을 추출하여 구축하였다. 이렇게 생성된 자료들의 분광 다양성을 주성분 분석(Principle Component Analysis; PCA)를 통해 분석하였으며, 부유사의 입도 분포, 부유사 종류, 수온 등과의 상관관계를 통해 분광 특성과 가장 상관관계가 높은 물리적 인자를 규명하였다. 더불어 구축된 자료를 바탕으로 기계학습 기반 주요 특징 선택 알고리즘인 재귀적 특징 제거법 (Recursive Feature Elimination)과 기계학습기반 회귀 모형인 Support Vector Regression을 결합하여 초분광 영상 기반 부유사 농도 예측 모형을 개발하였으며, 이 결과를 원격탐사 계측 연구에서 일반적으로 사용되어 오던 최적 밴드비 분석 (Optimal Band Ratio Analysis; OBRA) 방법으로 도출된 회귀식과 비교하였다. 그 결과, 기존의 OBRA 기반 방법은 비선형성을 증가시켜도 좁은 영역의 파장대만을 고려하는 한계점으로 인해 부유사의 다양한 분광 특성을 반영하지 못하였으며, 본 연구에서 제시한 기계학습 기반 예측 모형은 420 nm~1000 nm에 걸쳐 폭 넓은 파장대를 고려함과 동시에 높은 정확도를 산출하였다. 최종적으로 개발된 모형을 적용해 다양한 유사 조건에 대한 부유사 시공간 분포를 매핑한 결과, 시공간적으로 고해상도의 부유사 농도 분포를 산출하는 것으로 밝혀졌다.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.457-459
• /
• 2002

Sunlight causes various types of adverse skin changes on the sun-exposed areas of the skin, in which the most hazardous one is the induction of malignant skin tumours. FT -IR spectra were obtained from specimens excised from normal skin, BCCs, SCCs, MMs, nevi, lesions of solar keratosis and Bowen's disease. Tissue samples from freshly frozen specimens were cut into 2 sections in strictly sequential order to be stained with H & E for histopathological analysis, and then to be air-dried on CaF$_2$ slide glasses for further spectral data acquisition from defined area of interest. Intra- and inter-sample variations were estimated within grouped lesion categories according to each skin component. Mean spectra for each type of tissue pathology in the 800-1800 $cm^{-1}$ / region was interpreted using the classical group frequency approach that showed the most visible differences in spectra of benign, premalignant and malignant changes directly related to protein conformation and nucleic acid bases. The relative intensity of the nucleic acid peak was increased with progression to malignancy. In addition, PCA was able to evaluate and maximise the differences in the spectra by reducing the number of variables characterizing each patient and pathology category. This type of approach to non-destructively estimate the complexity of IR-spectra of inhomogeneous samples such as skin demonstrates the advantage of FT -IR microspectroscopy to be able to observe diseased states (benign, premalignant, malignant) and distinguish them from normal against a huge background of inter- and intra-subject variability.

• Journal of International Society for Simulation Surgery
• /
• v.1 no.1
• /
• pp.37-40
• /
• 2014

Purpose For living donor liver transplantation, liver segmentation is difficult due to the variability of its shape across patients and similarity of the density of neighbor organs such as heart, stomach, kidney, and spleen. In this paper, we propose an automatic segmentation of the liver using multi-planar anatomy and deformable surface model in portal phase of abdominal contrast-enhanced CT images. Method Our method is composed of four main steps. First, the optimal liver volume is extracted by positional information of pelvis and rib and by separating lungs and heart from CT images. Second, anisotropic diffusing filtering and adaptive thresholding are used to segment the initial liver volume. Third, morphological opening and connected component labeling are applied to multiple planes for removing neighbor organs. Finally, deformable surface model and probability summation map are performed to refine a posterior liver surface and missing left robe in previous step. Results All experimental datasets were acquired on ten living donors using a SIEMENS CT system. Each image had a matrix size of $512{\times}512$ pixels with in-plane resolutions ranging from 0.54 to 0.70 mm. The slice spacing was 2.0 mm and the number of images per scan ranged from 136 to 229. For accuracy evaluation, the average symmetric surface distance (ASD) and the volume overlap error (VE) between automatic segmentation and manual segmentation by two radiologists are calculated. The ASD was $0.26{\pm}0.12mm$ for manual1 versus automatic and $0.24{\pm}0.09mm$ for manual2 versus automatic while that of inter-radiologists was $0.23{\pm}0.05mm$. The VE was $0.86{\pm}0.45%$ for manual1 versus automatic and $0.73{\pm}0.33%$ for manaual2 versus automatic while that of inter-radiologist was $0.76{\pm}0.21%$. Conclusion Our method can be used for the liver volumetry for the pre-surgery planning of living donor liver transplantation.

• Journal of the Korean earth science society
• /
• v.25 no.7
• /
• pp.604-614
• /
• 2004

Using three-components geomagnetic data from a permanent geomagnetic observatory in Icheon, we have computed the power spectrum of each geomagnetic component, amplitude, phase and estimation error of transfer function for each day in the 6 months period July 2002${\sim}$December 2002. The temporal variation of power spectrum have random appearances with repeating relative strong and weak magnitude, which is considered as solar activities. However, there is no clear long-term trend. In the case of amplitude, phase and error of transfer function, even though there are some random patterns over the periods of 1000 s and under 100 s, they seem to be comparatively stable without manifest temporal changes. Futhermore, we have estimated electrical field by assuming P$_{1}\;^{0}$ spherical harmonics and then calculated the approximated apparent resistivity for each day. As a result, the variations of resistivity depend on the temporal magnitude of spectral power in horizontal magnetic fields rather than hydrological changes in near surface.

• Korean Journal of Soil Science and Fertilizer
• /
• v.50 no.3
• /
• pp.150-161
• /
• 2017

This study was conducted with the data of monitoring on soil chemical properties of rice paddy soils in Gyeongbuk Province. The selected soil chemical properties were analyzed every 4 year from 1999 to 2015. The soil pH measured in 2015 was higher than pH 6.0, which was 0.3-0.4 pH unit higher than data until 2007 survey year. The mean content of organic matter was greater than $24g\;kg^{-1}$ since 2003, but 35% of soil samples remained below the recommended level ($20-30g\;kg^{-1}$) in 2015. The mean concentration of available phosphate was maintained at $40mg\;kg^{-1}$ higher than the upper recommendation level ($80-120mg\;kg^{-1}$), and more than 40% of paddy soils tested were found to have less than the recommendation level during the survey period. The exchangeable K concentration ranged from 0.25 to $0.39cmol_c\;kg^{-1}$. Exchangeable Ca showed an average at the optimum range ($5.0-6.0cmol_c\;kg^{-1}$) during the monitoring period. Exchangeable Mg decreased linearly ($0.02cmol_c\;kg^{-1}\;year^{-1}$) from $1.55cmol_c\;kg^{-1}$ as of 1999 to below the lower level of the recommendation range ($1.5-2.0cmol_c\;kg^{-1}$). The amount of available $SiO_2$ was increased significantly from 2011 to over the recommendation level (${\geq}157mg\;kg^{-1}$). It was revealed that the soil chemical properties of rice paddy fields was influenced by topology, soil texture, type and region as result of principal component analysis or cluster analysis. Therefore, an assessment on chemical properties of rice paddy soils should be performed to consider various soil physical conditions and agronomic practices such as fertilization, cropping system, and so on. Because of the high variability of nutrient levels across Gyeongbuk Province, nutrient management based on soil fertility test is required by respective farm land unit.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.149-153
• /
• 2006

Precipitation is the most important component and critical to the study of water and energy cycle. This study investigates the propagation of precipitation retrieval uncertainty in the simulation of hydrologic variables for varying spatial resolution on two different vegetation cover. We explore two remotely sensed rain retrievals (space-borne IR-only and radar rainfall) and three spatial grid resolutions. An offline Community Land Model (CLM) was forced with in situ meteorological data In turn, radar rainfall is replaced by the satellite rain estimates at coarser resolution $(0.25^{\circ},\;0.5^{\circ}\;and\;1^{\circ})$ to determine their probable impact on model predictions. Results show how uncertainty of precipitation measurement affects the spatial variability of model output in various modelling scales. The study provides some intuition on the uncertainty of hydrologic prediction via interaction between the land surface and near atmosphere fluxes in the modelling approach.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.529-534
• /
• 2009

Climate models, both global and regional, have increased in sophistication and are being run at increasingly higher resolutions. The Land Surface Models (LSMs) coupled to these climate models have evolved from simple bucket models to sophisticated Soil-Vegetation-Atmosphere Transfer (SVAT) schemes needed to support complex linkages and processes. However, some underpinnings of terrestrial hydrologic parameterizations so crucial in the predictions of surface water and energy fluxes cause model errors that often manifest as non-linear drifts in the dynamic response of land surface processes. This requires the improved parameterizations of key processes for the terrestrial hydrologic scheme to improve the model predictability in surface water and energy fluxes. The Common Land Model (CLM), one of state-of-the-art LSMs, is the land component of the Community Climate System Model (CCSM). However, CLM also has energy and water biases resulting from deficiencies in some parameterizations related to hydrological processes. This research presents the implementation of a selected set of parameterizations and their effects on the runoff prediction. The modifications consist of new parameterizations for soil hydraulic conductivity, water table depth, frozen soil, soil water availability, and topographically controlled baseflow. The results from a set of offline simulations are compared with observed data to assess the performance of the new model. It is expected that the advanced terrestrial hydrologic scheme coupled to the current CLM can improve model predictability for better prediction of runoff that has a large impact on the surface water and energy balance crucial to climate variability and change studies.

• Analytical Science and Technology
• /
• v.16 no.2
• /
• pp.143-151
• /
• 2003

In the present study, we made measurements of PM-bound metal concentrations from seven different urbanized locations in Seoul for the period covering March 2001 through May 2002. The measurement data were analyzed to explore the possible influences of spatial factors on metal distribution characteristics. To check for the importance of such aspects on metal distribution characteristics, the measured data were compared between different metals and between different sites by several criteria including (1) coefficient of variation (CV) values; (2) temporal variability; and (3) the abundance of strongly correlated pairs. The overall results of our study indicate strong diversity in the distribution characteristics of different metals. It is found that some metals (like Fe, Mn, and Pb) tend to exhibit strong compatibility among different study sites. However, no such compatibility appears to exist for certain metals like Cu. To account for the importance of spatial factors, complex relationships between source/sink processes and geochemical characteristics of a given metallic component may have to be examined in a systematic manner.

• Ocean and Polar Research
• /
• v.26 no.4
• /
• pp.543-550
• /
• 2004

Dense macroalgal assemblages are a common feature of the rocky subtidal habitats along the coast of Geumo Archipelago in the central South Sea of Korea, but are highly variable in space. This study addresses two questions concerning the algal assemblages: (1) how variable the distribution, abundance and species composition of the assemblages are in space, and (2) how closely the distribution, abundance and species composition of the assemblages are correlated to the spatial variation in abiotic factors. To answer these questions, we investigated 30 sites along the coast in autumn of 2003. The nonmetric multidimensional scaling analysis showed that there were strong differences in the composition and abundance of species in the assemblages among the sites. The similarity among the sites based on presence/absence data was approximately 51%, whereas the similarity based on abundance data was less than 37%, suggesting that the abundance of species contributed much to these differences. There were also strong differences in the number of species, abundance and vertical distribution of the assemblages along the coast. Multiple regression analyses revealed that the number of species, abundance and vertical distribution of the assemblages had a positive relationship with water depth, but less than 58% of total variation in these variables was explained by this abiotic factor. The results suggest that spatial (between habitats) variation is an important and consistent component of subtidal algal assemblages in Geumo Archipelago and should be explained before any differences between localities are assessed.