• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.961-970
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• 2017

Despite of large demand for high spatial resolution products of aerosol properties from satellite remote sensing, it has been very difficult due to the weak signal by a single pixel and higher noise from clouds. In this study, aerosol retrieval algorithm with the high spatial resolution ($500m{\times}500m$) was developed using Geostationary Ocean Color Imager (GOCI) data during the Korea-US Air Quality (KORUS-AQ) period in May-June, 2016.Currently, conventional GOCI Yonsei aerosol retrieval(YAER) algorithm provides $6km{\times}6km$ spatial resolution product. The algorithm was tested for its best possible resolution of 500 m product based on GOCI YAER version 2 algorithm. With the new additional cloud masking, aerosol optical depth (AOD) is retrieved using the inversion method, aerosol model, and lookup table as in the GOCI YAER algorithm. In some cases, 500 m AOD shows consistent horizontal distribution and magnitude of AOD compared to the 6 km AOD. However, the 500 m AOD has more retrieved pixels than 6 km AOD because of its higher spatial resolution. As a result, the 500 m AOD exists around small clouds and shows finer features of AOD. To validate the accuracy of 500 m AOD, we used dataset from ground-based Aerosol Robotic Network (AERONET) sunphotometer over Korea. Even with the spatial resolution of 500 m, 500 m AOD shows the correlation coefficient of 0.76 against AERONET, and the ratio within Expected Error (EE) of 51.1%, which are comparable to the results of 6 km AOD.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.2
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• pp.93-101
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• 2015

This study was conducted to analyze the relationship between tree-ring growth of Quercus acutissima and climatic variables by dendroclimatological method. Annual tree-ring growth data of Quercus acutissima collected by the $5^{th}$ National Forest Inventory (NFI5) were organized to analyze the spatial distribution of the species growth pattern. To explain the relationship between tree-ring growth of Quercus acutissima and climatic variables, monthly temperature and precipitation data from 1950 to 2010 were compared with tree-ring growth data for each county. When tree-ring growth data were analyzed through cluster analysis based on similarity of climatic conditions, four clusters were identified. In addition, index chronology of Quercus acutissima for each cluster was produced through cross-dating and standardization procedures. The adequacy of index chronologies was tested using basic statistics such as mean sensitivity, auto correlation, signal to noise ratio, and expressed population signal of annual tree-ring growth. Response function analysis was conducted to reveal the relationship between tree-ring growth and climatic variables for each cluster. The results of this study are expected to provide valuable information necessary for estimating local growth characteristics of Quercus acutissima and for predicting changes in tree growth patterns caused by climate change.

• YAKHAK HOEJI
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• v.59 no.3
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• pp.98-106
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• 2015

Analytical method for related substances can be categorized into two methods depending on the necessity of reference standard (RS). The analytical method of related substances with RS is fast and accurate, but it's very expensive and technically difficult to synthesize RS due to their complicated structure. Another method is using relative retention time (RRT) and relative response factor (RRF) which are already validated with RS. Validation of this method is not easy and time consuming, but once it has been developed, it can save cost and time. In this study, we developed the analytical method for related substances of fenofibrate using RRT and RRF. We validated the method by evaluating specificity, linearity, accuracy and precision according to the "Manual for Guideline Application for Validation of Analytical Procedures" of MFDS. Also, we calculated RRT and RRF between fenofibrate and fenofibrate related substances. The results of this study showed high specificity for fenofibrate and fenofibrate related substances. Correlation coefficient(r) of all substances were more than 0.99, and the recovery of fenofibrate, fenofibrate related substance I, II and III were 99.44%, 100.84%, 99.14% and 101.58%, respectively. Precision of fenofibrate and its related substances were ranged between RSD 0.29% and 0.93%. Quantification limits of fenofibrate, fenofibrate related substance I, II and III were determined to be $0.03{\mu}g/ml$, $0.05{\mu}g/ml$, $0.04{\mu}g/ml$ and $0.02{\mu}g/ml$, respectively by confirming signal to noise ratio of each chromatogram. The RRT for fenofibrate related substance I, II and III were determined to be 0.35, 0.41 and 1.34, respectively. Also, the RRF for fenofibrate related substance I, II and III were determined to be 1.28, 0.98 and 0.79, respectively. The developed method was applied to determine contents for fenofibrate related substances in commercial fenofibrate (active pharmaceutical ingredient). As a result, developed analytical methods of related substances will be used for revising the monograph of fenofibrate in Korean Pharmacopoeia revision and contribute quality control of drugs by improving cost and time consuming problem of RS.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.8
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• pp.34-41
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• 2017

Vehicle to Infrastructure(V2I) communication means the technology between the vehicle and the roadside unit to provide the Intelligent Transportation Systems(ITS) and Telematic services. The vehicle collects information about the probe data through the evolved Node B(eNodeB) and after that eNodeB provides road conditions or traffic information to the vehicle. To provide these V2I communication services, we need a link adaptation technology that enables reliable and higher transmission rate. The receiver transmits the estimated Channel State Information(CSI) to transmitter, which uses this information to enable the link adaptation. However, due to the rapid channel variation caused by vehicle speed and the processing delay between the layers, the estimated CSI quickly becomes outdated. For this reason, channel interpolation and prediction scheme are needed to achieve link adaptation in V2I communication system. We propose the Advanced Discrete Prolate Spheroidal Sequence(ADPSS) channel interpolation and prediction scheme. The proposed scheme creates an orthonomal basis, and uses a correlation matrix to interpolate and predict channel. Also, smoothing is applied to frequency domain for noise removal. Simulation results show that the proposed scheme outperforms conventional schemes with the high speed and low speed vehicle in the freeway and urban environment.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.157-164
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• 2005

Urban conditions such as underground facilities and ambient noises due to cultural activity restrict the application of conventional geophysical techniques in general. We used the refraction microtremor (REMI) technique as an alternative way to get the geotechnical information, in particular shear-wave (S-wave) velocity information, at a site along an existing rail road. The REMI method uses ambient noises recorded using standard refraction equipment to derived shear-wave velocity information at a site. It does a wavefield transformation on the recorded wavefield to produce Rayleigh wave dispersion curve, which are then picked and modeled to get the shear-wave velocity structure. At this site the vibrations from the running trains provided strong noise sources that allowed REMI to be very effective. REMI was performed along the planned new underground rail tunnel. In addition, Suspension PS logging (SPS) were carried out at selected boreholes along the profile in order to draw out the quantitative relation between the shear wave velocity from the PS logging and the rock mass rating (RMR) determined from the inspection of the cores recovered from the same boreholes, These correlations were then used to relate the shear-wave velocity derived from REMI to RMR along the entire profile. The correlation between shear wave velocity and RMR was very good and so it was possible to estimate the RMR of the total zone of interest for the design of underground tunnel,

• Journal of the Korean Geographical Society
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• v.49 no.1
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• pp.45-56
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• 2014

Data composite methods have been typically applied to satellite-based vegetation index(VI) data to continuously acquire vegetation greenness over the land surface. Data composites are useful for construction of long-term archives of vegetation indices by minimizing missing data or contamination from noise. In addition, if multi-sensor vegetation indices that are acquired during the same composite periods are used interchangeably, data stability and continuity may be significantly enhanced. This study evaluated the influences of sensor geometry on MODIS vegetation indices and investigated data compatibility of two difference vegetation indices, the Normalized Difference Vegetation Index(NDVI) and the Enhanced Vegetation Index(EVI), for potential improvement of long-term data construction. Relationships between NDVI and EVI turned out statistically significant with variations among vegetation covers. Due to their curvilinear relationships, NDVI became saturated and leveled off as EVI reached high ranges. Correlation coefficients between Terra- and Aqua-based vegetation indices ranged from 0.747 to 0.963 for EVI, and from 0.641 to 0.880 for NDVI, showing better compatibility for EVI compared to NDVI. In-depth analyses of VI outliers that deviated from regression equations constructed from the two different sensors remain as a future study to improve their compatibility.

• Journal of Broadcast Engineering
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• v.20 no.6
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• pp.818-826
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• 2015

Recently, objective image quality assessment (IQA) methods that elaborately reflect the visual quality perception characteristics of human visual system (HVS) have actively been studied. Among those characteristics of HVS, luminance adaptation (LA) effect, indicating that HVS has different sensitivities depending on background luminance values to distortions, has widely been reflected into many existing IQA methods via Weber's law model. In this paper, we firstly reveal that the LA effect based on Weber's law model has inaccurately been reflected into the conventional IQA methods. To solve this problem, we firstly derive a new LA effect-based Local weight Function (LALF) that can elaborately reflect LA effect into IQA methods. We validate the effectiveness of our proposed LALF by applying LALF into SSIM (Structural SIMilarity) and PSNR methods. Experimental results show that the SSIM based on LALF yields remarkable performance improvement of 5% points compared to the original SSIM in terms of Spear rank order correlation coefficient between estimated visual quality values and measured subjective visual quality scores. Moreover, the PSNR (Peak to Signal Noise Ratio) based on LALF yields performance improvement of 2.5% points compared to the original PSNR.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.16 no.1
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• pp.23-27
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• 2005

Background and Objectives : Voice disorders can cause problems in patients with benign vocal cord lesions emotionally, physically, economically and functionally. Neither subjective nor objective voice examinations can evaluate such factors adequately. The Voice Handicap Index (VHI) subjectively evaluates voice disorders in terms of physical, functional, emotional factors and measures the patient's perception of the impact of voice disorder. The purpose of this study is to evaluate the usefulness of VHI in the patients with benign vocal cord lesions. Materials and Method : The authors evaluated 37 patients who experienced laryngeal microsurgery for benign vocal cord lesions from september 2003 to August 2004. The VHI was used to measure the postoperative changes of the patient's perception and acoustic analysis and aerodynamic tests were also done. Statistical analysis was done using paired t-test and Pearson's correlation. Results : The VHI scores showed statistically significant reductions postoperatively. In acoustic analysis, jitter and shimmer had statistically significant reductions after surgery but noise-to-harmonics ratio did not. A statistically significant change in the average MFR and MPT perioperatively was found. The relationship between VHI and acoustic, aerodynamic analysis attained statistical significance. Conclusion : The VHI is a useful assessment tool to monitor the patient's self-perception of voice change after the surgery of benign vocal cord lesions. The VHI measurement, when combined with acoustic and aerodynamic analyses, will be helpful in comparing functional outcomes after voice surgery.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.27 no.2
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• pp.102-107
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• 2016

Background and Objectives : Vocal polyps are caused by inflammation induced by stress or irritation. Many patients with vocal polyps complain voice discomfort. For vocal polyps, surgery such as laryngeal microsurgery has been the mainstay of management. We analyzed the clinical features of vocal polyps, and how the size and location of vocal polyps affect the outcomes of surgery. Methods : We retrospectively reviewed 42 patients from March 2014 to December 2015, who were diagnosed as unilateral single vocal polyp. When we operated on a vocal polyp with laryngeal microscopy, we measured their size and location. The quality of voice was evaluated by GRABS scale, jitter, shimmer, NHR (noise to harmonic ratio), MPT (maximum phonation time), and VHI (voice handicap index) before operation and 4 weeks after operation. Results : When we divided the patients into large-sized vocal polyp group (the longest length >3 mm) and small-sized vocal polyp group (the longest length ${\leq}3mm$), all parameter differences tend to be greater at large sized vocal polyp. However, these differences were not statistically significant (p>0.05). When we divided into two groups depending on the volume of vocal polyp, no distinct tendency was found. When we compared the location (anterior, mid and posterior) of vocal polyp with the improvement of voice quality, more change was found at mid portion vocal polyp, except the difference of VHI. However, these differences were also not statistically significant (p>0.05). Conclusion : All parameter differences tend to be greater at large vocal polyp and polyp of the mid location.

• Journal of the Korean Society of Radiology
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• v.5 no.6
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• pp.357-361
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• 2011

In this study, the liquid-crystal optical modulation X-ray detection system using a CdS which is a family of II-IV compound semiconductor was proposed. The system consist of the detector, the signal processing part, the liquid-crystal driving parts, microcontroller, and I/O parts, and was designed to be suitable for miniaturization and portable. In addition, the system can measure a wide range X-ray by using the detecting range selection. In order to evaluate the performance of the proposed system, the CdS sensor's output characteristics were confirmed in accordance with changes of dose, and excellent correlation was determined. And also, the optical penetration ratio was discussed in accordance with changes of the applied voltage by measuring the change of the liquid-crystal in accordance with changes of the applied voltage. Through these results, the characteristics of the liquid-crystal optical modulation system such as the excellent reproducibility and the noise immunity were confirmed. And we considered that the CdS cell-based liquid-crystal optical modulated portable X-ray detection system could be applied to compact, low-cost, portable system.