• Journal of Korean Society of Forest Science
• /
• v.109 no.3
• /
• pp.350-360
• /
• 2020

The purpose of this study was to identify and prioritize the key indicators and drivers of forest thinning. The research for this study was designed in two-phases: 1) sequential, exploratory, mixed methods research that was initiated with a qualitative phase (Delphi technique), and 2) the quantitative phase (Analytic Hierarchy Process technique). Results indicated that management and planning were the most important factors in the first level of criteria among the "management and planning," "directing and monitoring," "supervision," and "quality of thinning work." On the sub-criteria level, "the quality of forest management planning" was indicated as the most important factor among the ten sub-criteria. Our results have shown that the developed forest thinning evaluation factors were a well-represented characteristic for a variety of forest thinning work in Korea.

• The Journal of the Korea Contents Association
• /
• v.18 no.12
• /
• pp.208-217
• /
• 2018

The purpose of this study was to provide information on the treatment and management of diabetic patients using all the available data of the Korea National Health and Nutrition Examination Survey (KNHANES, 2013-2015) on the serological and complication patterns of cardiovascular disease (CVD) according to the duration of diabetes mellitus (DM). KNHANES consists of health questionnaires, screenings, and nutrition surveys. The study subjects were 1,316 persons who were aged between 18 and 80 years and who answered the duration of DM. DM was classified as 0-5, 6-10, 11-15, 16-20, and over 20 years according to duration of DM. The longer the duration of DM, the older the BMI, the lower the smoker, the higher the HbA1c and the lower the glomerular filtration rate. Total cholesterol, LDL-C and triglyceride levels were low and HDL-C levels were similar. The proportion of patients receiving insulin and oral hypoglycemic agents increased. The longer the duration of DM, the worse blood glucose control and the increased risk of microvascular and macrovascular complications. To prevent these complications, intensive care and monitoring should be used to control the risk factors.

• Journal of Korean Society of Forest Science
• /
• v.113 no.3
• /
• pp.271-281
• /
• 2024

The purpose of this study is to establish baseline data on the habitat status of Dracocephalum argunense Fisch. ex Link by identifying its vegetation structure and correlating environmental factors. A total of 9 vegetation plots (10 m×10 m) were surveyed. Cluster analysis revealed a total of three clusters: Quercus aliena (Group 1), Pinus thunbergii-Rubus parvilolius (Group 2), and Indigofera kirilowii-Zanthoxylum piperitum (Group 3). The importance value of D. argunense was the highest in Group 2, with a value of 6.19. Diversity analysis indicated a range of 2.747-3.166, but differences among the groups was not statistically significant (p>0.05). In the areas surrounding sedimentary rock zones, invasive plants were identified as indicator species, emphasizing the need for monitoring invasive species in the future. Although D. argunense exhibits good adaptability to moisture and atmospheric conditions due to its diverse habitats (forest and coast), there is a risk of decline due to interspecific competition and human activities, as analyzed in this study.

• Korean Journal of Soil Science and Fertilizer
• /
• v.43 no.3
• /
• pp.374-383
• /
• 2010

Microwave radar can penetrate cloud cover regardless of weather conditions and can be used day and night. Especially a ground-based polarimetric scatterometer has advantages of monitoring crop conditions continuously with full polarization and different frequencies. Kim et al. (2009) have measured backscattering coefficients of paddy rice using L-, C-, X-band scatterometer system with full polarization and various angles during the rice growth period and have revealed the necessity of near-continuous automatic measurement to eliminate the difficulties, inaccuracy and sparseness of data acquisitions arising from manual operation of the system. In this study, we constructed an X-band automatic scatterometer system, analyzed scattering characteristics of paddy rice from X-band scatterometer data and estimated rice growth parameter using backscattering coefficients in X-band. The system was installed inside a shelter in an experimental paddy field at the National Academy of Agricultural Science (NAAS) before rice transplanting. The scatterometer system consists of X-band antennas, HP8720D vector network analyzer, RF cables and personal computer that controls frequency, polarization and data storage. This system using automatically measures fully-polarimetric backscattering coefficients of rice crop every 10 minutes. The backscattering coefficients were calculated from the measured data at a fixed incidence angle of $45^{\circ}$ and with full polarization (HH, VV, HV, VH) by applying the radar equation and compared with rice growth data such as plant height, stem number, fresh dry weight and Leaf Area Index (LAI) that were collected at the same time of each rice growth parameter. We examined the temporal behaviour of the backscattering coefficients of the rice crop at X-band during rice growth period. The HH-, VV-polarization backscattering coefficients steadily increased toward panicle initiation stage, thereafter decreased and again increased in early-September. We analyzed the relationships between backscattering coefficients in X-band and plant parameters and predicted the rice growth parameters using backscattering coefficients. It was confirmed that X-band is sensitive to grain maturity at near harvesting season.

• Korean Journal of Remote Sensing
• /
• v.27 no.2
• /
• pp.191-201
• /
• 2011

Soybean has widely grown for its edible bean which has numerous uses. Microwave remote sensing has a great potential over the conventional remote sensing with the visible and infrared spectra due to its all-weather day-and-night imaging capabilities. In this investigation, a ground-based polarimetric scatterometer operating at multiple frequencies was used to continuously monitor the crop conditions of a soybean field. Polarimetric backscatter data at L, C, and X-bands were acquired every 10 minutes on the microwave observations at various soybean stages. The polarimetric scatterometer consists of a vector network analyzer, a microwave switch, radio frequency cables, power unit and a personal computer. The polarimetric scatterometer components were installed inside an air-conditioned shelter to maintain constant temperature and humidity during the data acquisition period. The backscattering coefficients were calculated from the measured data at incidence angle $40^{\circ}$ and full polarization (HH, VV, HV, VH) by applying the radar equation. The soybean growth data such as leaf area index (LAI), plant height, fresh and dry weight, vegetation water content and pod weight were measured periodically throughout the growth season. We measured the temporal variations of backscattering coefficients of the soybean crop at L, C, and X-bands during a soybean growth period. In the three bands, VV-polarized backscattering coefficients were higher than HH-polarized backscattering coefficients until mid-June, and thereafter HH-polarized backscattering coefficients were higher than VV-, HV-polarized back scattering coefficients. However, the cross-over stage (HH > VV) was different for each frequency: DOY 200 for L-band and DOY 210 for both C and X-bands. The temporal trend of the backscattering coefficients for all bands agreed with the soybean growth data such as LAI, dry weight and plant height; i.e., increased until about DOY 271 and decreased afterward. We plotted the relationship between the backscattering coefficients with three bands and soybean growth parameters. The growth parameters were highly correlated with HH-polarization at L-band (over r=0.92).

• Journal of Korea Water Resources Association
• /
• v.49 no.10
• /
• pp.835-849
• /
• 2016

Accurate drought outlook and drought monitoring have been preceded recently to mitigate drought damages that further deepen. This study improved the limitations of the previous MSWSI (Modified Surface Water Supply Index) used in Korea and carried out probabilistic drought forecasts based on ensemble technique with the improved MSWSI. This study investigated available hydrometeorological components in Geum river basin and supplemented appropriate components (dam water level, dam release discharge) in addition to the four components (streamflow, groundwater, precipitation, dam inflow) usedin the previous MSWSI to each sub-basin. Although normal distribution was fitted in the previous MSWSI, the most suitable probabilistic distributions to each meteorological component were estimated in this study, including Gumbel distribution for precipitation and streamflow data; 2-parameter log-normal distribution for dam inflow, water level, and release discharge data; 3-parameter log-normal distribution for groundwater. To verify the improved MSWSI results using historical precipitation and streamflow, simulated drought situations were used. Results revealed that the improved MSWSI results were closer to actual drought than previous MSWSI results. The probabilistic forecasts based on ensemble technique with improved MSWSI were performed and evaluated in 2006 and 2014. The accuracy of the improved MSWSI was better than the previous MSWSI. Moreover, the drought index of actual drought was included in ranges of drought forecasts using the improved MSWSI.

• Korean Journal of Remote Sensing
• /
• v.31 no.6
• /
• pp.549-560
• /
• 2015

With the global scale impact of atmospheric $CO_2$ in global warming and climate system, it is necessary to monitor the $CO_2$ concentration continuously on a global scale, where satellite remote sensing has played a significant role recently. In this study, global monthly $CO_2$ concentrations obtained by satellite remote sensing were compared with ground-based measurements at Anmyeon-do and Gosan Korean Global Atmosphere Watch Center. Atmospheric $CO_2$ concentration has increased from 371.87 ppm in January 1999 to 405.50 ppm in December 2013 at Anmyeon-do station (KMA, 2013). Comparison of the continuous measurements by flask air sampling at Anmyeon-do shows the same trend and seasonal variations with those of global monthly mean dataset. Nevertheless, the trends of $CO_2$ over Northeast Asia showed the higher than those of global and the trends also changes with different slope. $CO_2$ products derived from Greenhouse Gases Observing Satellite (GOSAT) and Atmospheric Infrared Sounder (AIRS) were compared with ground-based measurement at Anmyeon-do. The monthly mean values of GOSAT and AIRS data are systemically lower than those obtained at Anmyeon-do, however, the seasonal cycle of satellite products present the similar trend with values of global and Anmyeon-do. The accuracy of $CO_2$ products from GOSAT and AIRS were evaluated statistically for two years from January 2011 to December 2012. GOSAT showed good correlation with the correlation coefficient, RMSD and bias of 0.947, 5.610 and -5.280 to ground-based measurements respectively, while AIRS showed reasonable comparison with 0.737, 8.574 and -7.316 at Anmyeon-do station, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.311-312
• /
• 2012

본 발표에서는 광학적 분석 시스템에 적용 가능한 발광소자(광원)과 수광소자(광센서)를 집적화시키는 모듈(수 발광 집적모듈) 기술을 제시하고자 한다. 이러한 수-발광 집적모듈은 다양한 응용 분야에 적용 될 수 있다. 예를 들어, 광신호 감지를 위한 광통신용 송-수신 모듈(optical communication), 의료/진단 분야에서 단백질/DNA/박테리아 등의 검출 및 분석에 관한 바이오 센서(bio-sensor), 그리고 대기(가스)/수질 모니터링에 관한 환경센서 등 매우 광범위한 분야에 해당되는 요소 기술이라 할 수 있다. 특히, 이들 분야들 중 바이오 물질을 분석하고 검출하는 광학적 바이오 센서 기술은 높은 경제적 가치와 산업적 성장 잠재력으로 인해 오랫동안 활발한 연구가 진행되어 오고 있다. 이러한 광학적 바이오 센서에서 가장 범용적인 방법 중 하나가 항온-항체 면역반응을 기반으로 하는 형광 검출(fluorescence detection) 기법이다. 이러한 시스템은 전체적으로 광원, 광학계, 그리고 센서로 구성되는데 기존에 일반적으로 사용되고 있는 형광 현미경의 경우는 민감도가 우수하다는 장점은 있으나 상당히 고가이고 부피가 크며 복잡한 광학구성으로 이루어져 있다는 한계점을 가지고 있다. 이러한 맥락에서 고민감도를 확보하면서 휴대성, 고속처리, 저가 등의 특성을 가진 시스템에 대한 요구가 갈수록 증가하고 있다. 이를 해결하기 위한 핵심기술 중의 하나가 수-발광 부분을 집적화 시키는 기술이라 할 수 있다. 본 연구에서는 바이오 센서 기술의 하나로서 형광을 측정하여 혈액내의 진단 지표인자를 검출할 수 있는 휴대용 혈액진단기기에 적용되는 소형 수 발광 집적 모듈을 개발하였다. 혈액내의 검출 성분의 양에 따라 형광의 세기가 변화하게 됨으로써 정량적인 검출이 가능한 원리이다. 모듈의 구조는 크게 광원(발광소자), 광학계, 그리고 광센서(수광소자) 세 영역으로 나누어 진다. 광원은 635 nm 적색 레이저다이오드로서 형광체(Alexa Fluor 647/발광파장: 668 nm)를 여기 시키는 기능을 하며 장착된 볼렌즈 의해 샘플의 형광체 영역으로 집광된다. 광학계는 크게 시준렌즈(collimating lens)와 광학필터로 구성됨으로써 샘플로부터 발생되는 광을 적절하게 수광소자로 전달하는 기능을 하게 된다. 여기서 광학필터의 경우는 기본적으로 Distributed Bragg's Reflector(DBR) 구조로써 실리콘(Si) 포토다이오드 상부에 모노리식(monolithic)하게 형성되며 검출 샘플로부터 진행되는 레이저 광(잡음의 주원인)은 차단하고 형광(광신호)만 통과 시키는 기능을 하게 된다. 따라서 신호 대 잡음비(S/N ratio)를 향상시키기 위해서는 정밀한 광 필터링 기능이 요구됨으로써 박막의 세밀한 공정 조건과 구조적-광학적 특성 분석이 수행되었다. 마지막으로 포토다이오드 소자는 일반적인 구조 이외에 중앙에 원형 구멍이 형성된 특별한 구조가 적용된다. 이것은 포토다이오드 구조에 변화를 줌으로써 모듈 구조를 효율적으로 응용할 수 있다는 의미를 갖는다. 또한 포토다이오드의 전기적-광학적 측정 분석을 통해 잡음 및 감도 특성이 세부적으로 조사되며 형광신호를 효과적으로 측정할 수 있음을 확인하였다. 최종적으로 제작된 모듈은 약 $1{\times}1{\times}1cm^3$ 내외 정도의 크기를 갖는다. 요약하자면 본 발표에서는 광학적 바이오센서에 적용할 수 있는 소형 수-발광 소자 집적모듈을 소개한다. 전체 모듈 설계는 최소한의 부피를 가짐과 동시에 측정의 정밀성을 향상시키는데 초점을 맞추어 진행하였다. 세부요소인 광학필터와 포트다이오드의 경우 잡음 및 민감도에 미치는 중요성 때문에 세밀한 공정 및 특성분석이 수행되었다. 결론적으로 독자적인 설계 및 공정을 통해 휴대성 및 정밀성 등의 목적에 부합한 경쟁력 있는 수-발광 소자 집적모듈 제작 기술을 확보하였다.

• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.2
• /
• pp.126-135
• /
• 2015

Increase of delivery effect of pollutant loads and surface runoff due to urbanization of catchment area results in serious environmental problems in receiving urban streams. This study aims to develop integrated stormwater management system to assist efficient urban stream flow and water quality control using information from the Storm Water Management Model (SWMM), real time water level and quality monitoring system and remote or automatic treatment facility control system. Based on field observations in the study site, most of the pollutant loads are flushed within 4 hours of the rainfall event. SWMM simulation results indicates that the treatment system can store up to 6 mm of cumulative rainfall in the study catchment area, and this means any type of normal rainfall situation can be treated using the system. Relationship between rainfall amount and fill time were developed for various rainfall duration for operation of stormwater treatment system in this study. This study can further provide inputs of river water quality model and thus can effectively assist integrated water resources management in urban catchment and streams.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.4
• /
• pp.20-29
• /
• 2022

The operational modal analysis (OMA) technique, which extracts the modal parameters of a structural system using ambient vibrations, has been actively developed as a field of structural health monitoring of cable-supported bridges. In this paper, the short and long-term modal parameters of a cable-stayed bridge were evaluated using the acceleration data obtained from the two ambient vibration tests (AVTs) and three years of continuous measurements. A total of 27 vertical modes and 1 lateral mode in the range 0.1 ~ 2.5 Hz were extracted from the high-resolution AVTs which were conducted in the 6th and 19th years after its completion. Existing OMA methods such as Peak-Picking (PP), Eigensystem Realization Algorithm with Data Correlation (ERADC), Frequency Domain Decomposition (FDD) and Time Domain Decomposition (TDD) were applied for modal parameters extraction, and it was confirmed that there was no significant difference between the applied methods. From the correlation analysis between long-term natural frequencies and environmental factors, it was confirmed that temperature change is the dominant factor influencing natural frequency fluctuations. It was revealed that the decreased natural frequencies of the bridge were not due to changes in structural performance and integrity, but to the environmental effects caused by the temperature difference between the two AVTs. In addition, when the TDD technique is applied, the accuracy of extracted mode shapes is improved by adding a proposed algorithm that normalizes the sequence so that the autocorrelations at zero lag equal 1.