• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.279-279
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• 2022

최근 이미지분석 기술은 하드웨어 및 소프트웨어 기술의 급격한 발전으로 인해 의학, 생물학, 지리학, 재료공학 등에서 수많은 연구 분야에서 광범위하게 활용되고 있으며, 이미지분석은 다량의 토사에 대하여 입경을 포함한 형상학적 특성을 간편하게 정량화 할 수 있기 때문에 매우 효과적인 분석 방법으로 판단된다. 현재 모래의 입도분석 방법으로는 신뢰성 있는 체가름 시험법(KSF2302) 등이 있으나, 번거로운 처리과정과 많은 시간이 소요된다. 또한 입자형상은 입경이 세립 할수록 직접 측정이 어렵기 때문에, 최근에는 이미지 분석을 이용하는 방법이 시도되고 있다. 본 연구에서는 75㎛ 이상의 조립질 하상 토사 이미지를 취득하여, 입자들의 장·축단 길이, 면적, 둘레, 공칭직경 및 종횡비 등의 형상학적 특성인자를 자동으로 측정하는 프로그램 개발을 수행하였다. 프로그램은 이미지 분석에 특화된 라이브러리인 OpenCV(Open Source Computer Vision)를 적용하였다. 이미지 분석 절차는 크게 이미지 취득, 기하보정, 노이즈제거, 객체추출 및 형상인자 측정 단계로 구성되며, 이미지 취득시 패널의 하단에 Back light를 부착해 시료에 의해 발생되는 음영을 제거하였다. 기하보정은 원근변환(perspective transform)을 적용했으며, 노이즈 제거는 모폴로지 연산과 입자간의 중첩으로 인한 뭉침을 제거하기 위해 watershed 알고리즘을 적용하였다. 최종적으로 객체의 외곽선 추출하여 입자들의 다양한 정보(장축, 단축, 둘레, 면적, 공칭직경, 종횡비)를 산출하고, 분포형으로 제시하였다. 본 연구에서 제안하는 이미지분석을 적용한 토사의 형상학적 특성 측정 방법은 시간과 비용의 측면에서 보다 효율적으로 하상 토사에 대한 다양한 정보를 획득 할 수 있을 것으로 기대한다.

• Atmosphere
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• v.23 no.3
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• pp.293-305
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• 2013

Nonhydrostatic effects on convectively forced mesoscale flows in two dimensions are numerically investigated using a nondimensional model. An elevated heating that represents convective heating due to deep cumulus convection is specified in a uniform basic flow with constant stability, and numerical experiments are performed with different values of the nonlinearity factor and nonhydrostaticity factor. The simulation result in a linear system is first compared to the analytic solution. The simulated vertical velocity field is very similar to the analytic one, confirming the high accuracy of nondimensional model's solutions. When the nonhydrostaticity factor is small, alternating regions of upward and downward motion above the heating top appear. On the other hand, when the nonhydrostaticity factor is relatively large, alternating updraft and downdraft cells appear downwind of the main updraft region. These features according to the nonhydrostaticity factor appear in both linear and nonlinear flow systems. The location of the maximum vertical velocity in the main updraft region differs depending on the degrees of nonlinearity and nonhydrostaticity. Using the Taylor-Goldstein equation in a linear, steady-state, invscid system, it is analyzed that evanescent waves exist for a given nonhydrostaticity factor. The critical wavelength of an evanescent wave is given by ${\lambda}_c=2{\pi}{\beta}$, where ${\beta}$ is the nonhydrostaticity factor. Waves whose wavelengths are smaller than the critical wavelength become evanescent. The alternating updraft and downdraft cells are formed by the superposition of evanescent waves and horizontally propagating parts of propagating waves. Simulation results show that the horizontal length of the updraft and downdraft cells is the half of the critical wavelength (${\pi}{\beta}$) in a linear flow system and larger than ${\pi}{\beta}$ in a weakly nonlinear flow system.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.7-16
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• 2015

The transmitter of quadrature multiplexed GMSK (QM-GMSK) is composed of two quadrature multiplexed GMSK modulators. QM-GMSK has a slightly increased spectrum main lobe compared with $Q^2PSK$ or QMSK, but it has highly suppressed side lobes. As a result, practical spectrum efficiency of QM-GMSK is achieved. By replacing the baseband elementary pulses of QM-GMSK with their approximate, the squared sinusoid of half-period, offset-$Q^2PSK$($OQ^2PSK$) is obtained. The $OQ^2PSK$ signal has similar spectral properties to QM-GMSK. The transmitter of $OQ^2PSK$ can be simply implemented without the Gaussian lowpass filter, which is required in QM-GMSK transmitter. In this paper, we propose an overlapped pulse shaping in $OQ^2PSK$ with RC(raised-cosine) or SRC(squared raised-cosine) pulses of length longer than the symbol period. Power spectrum of the proposed modulation scheme exhibits further suppressed side lobes, hence enhanced spectrum efficiency is obtained. Simulation results indicate that BER performance of the proposed scheme is comparable to that of $OQ^2PSK$.

• Korean Journal of Plant Taxonomy
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• v.31 no.3
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• pp.283-309
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• 2001

Acer pictum complex (A. pictum Thunb. ex Murray with varieties, A. okamotoanum Nakai, A. truncatum Bunge) in eastern Asia causes frequent difficulty in identification. One hundred twenty five specimens from A. pictum complex of China, Korea and Japan and A. cappadocicum var. sinicum of China were compared to investigate patterns of intra- and interspecific variation and to evaluate a recognition of several species as well as many varieties using 22 characters for morphometric analysis. The first three PCA accounted for 59% of the total variance. No strong discontinuities existed among taxa with respect to fruit and leaf characters. Much overlap among all taxa occurred the central region of the scatter diagram. Many characters appeared to show some clinal variation with changes from east of China to Japan through Korea. This was true not only when all species as considered as a single taxon, but when characters of individual taxa were compared with geography. As one considers a path from the western part of the ranges to areas to the east, the leaves become larger in most respects and become increasingly many lobed (five to seven or nine). In general, there was a tendency toward larger nutlet with smaller wing in the area toward northeast of China (=A. truncatum), while in the east of ranges (Island Ullung-do), plants were larger with respect to characters of fruit and leaves (=A. okamotoanum). The morphological differentiation between A. okamotoanum and Japanese and Korean individuals of A. pictum was not considered sufficient to warrant recognition of either specific or varietal status and should be treated as con specific under A. pictum var. mono. Since the lectotype of Acer pictum had minute hairs uniformly on the under surface of leaves(A. pictum var. pictum), the glabrous type of A. pictum was called A. pictum var. mono as Ohahsi suggested. The univaraite analysis (the mean and maximum/minium of nutlet size and wing/nutlet length ratio) indicated geographical differentiation of northeastern populations, A. truncatum, was distinctive, but Korean individuals of A. truncatum showed an affinity between Chinese individuals of A. truncatum and Korean individuals of A. Pictum var. mono. The current results, together with qualitative character, trunk features, justify subspecific status for this taxon. The previous varieties of A. mono in Korea were indistinguishable from typical form of A. Pictum var. mono on the basis of the wing angle and nutlet size, rejecting continued recognition of these taxa as distinctive varieties. Therefore, it is recommended that only one polymorphic species of A. pictum be recognized in addition to three varieties.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.1-15
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• 2015

In order to outline the kinematics and movement history of a new Quaternary fault, Jingwan Fault in Dangjin, West Korea, we analyzed the geometry of the fault zone composed of a few gouge zones, and made ESR dating for fault gouge materials. The $N55^{\circ}E$ striking Jingwan Fault is a normal fault and exhibits a gradual change in dip (gentle in the lower part, steep in the upper part), indicating a listric fault. As for the fault gouge zone, its thickness varies and reaches 2~3 cm in the lower part or between basement rocks, and 20~30 cm in the middle-upper part or between the basement and Quaternary deposit. It is observed in the latter case that more than three gouge zones develop with different colors, and branch out and re-merge, or they are partly superimposed, indicating different movement episodes. The cumulative displacement is estimated to be about 10 m using the geological cross-sections, from which it is inferred that the total length of fault may be about 2.5 km on the basis of the empirical relation between cumulative displacement and fault length. Therefore, a more study would be needed to verify the entire fault length. The results of ESR dating for three gouge samples at different spots along the fault yields ages of $651{\pm}47$, $649{\pm}96$, and $436{\pm}66ka$, indicating at least two movement episodes. Slickenlines observed on the fault planes indicate a pure dip slip (normal faulting), which suggests that the ENE-WSW trending Jingwan Fault was presumably moved under a NNW-SSE extensional environment.

• Journal of the Korean Geophysical Society
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• v.6 no.3
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• pp.155-164
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• 2003

The validity and efficiency of the roll-along technique widely used in 2-D electrical resistivity survey are analyzed in case of the dipole-dipole and the Wenner-Schlumberger arrays by numerical modelling. The shallow anomalous resistivity bodies are successfully inverted both in the dipole-dipole and in the Wenner-Schlumberger arrays because the shallow data of pseudosection are not omitted by the roll-along technique. However, the deep anomalous resistivity bodies can not be well resolved due to the skip of observed data which is more significant in the Wenner-Schlumberger array having relatively poor horizontal coverage of obtaining data. Carrying out electrical survey adopting the dipole-dipole array, the skip of data is insignificant because it is unfeasible to expand the electrodes to the maximum electrode separation coefficient($n_max$) owing to low S/N ratio. In case of the Wenner-Schlumberger array, however, because it is generally feasible to expand the electrodes $n_max$ to the owing to high S/N ratio, it is highly possible that skip of data from the roll-along technique causes significant distortion of inversion results. Therefore, adopting the Wenner-Schlumberger array having deeper median depth(Edwards, 1977) than do the dipole-dipole array on condition of the same unit electrode spacing( ($a$) ) and $n_max$, it is recommended to determine $a$ based on not $n_max$but $n_prob$free from the skip of observing data and forward electrodes with keeping overlap interval 3/4 of the survey line length in order to reduce the distortion of resistivity structure and perform resistivity survey efficiently. These results are confirmed by numerical modelling.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.39-50
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• 2001

In proceeding with orthodontic treatment, the prediction for the shape, growth rate and growth direction of mandible plays a major role to set up the treatment plan and determine its period and prognosis. Various approaches being made so far have shown that the linear and angular measurement using lateral cephalograms are relatively accurate to estimate them. This study was purposed to find the shape of mandible more clearly by preventing the overlap of the Condyle head area which appears in lateral cephalogram, and to estimate its growth rate by comparing the growth quantity and ratio via lateral area measurement. This experimental was performed against 40 patients total, of which Class I of 14, Class II of 9 and Class III of 17 consist. Wide open lateral cephalograms of 40 patients were taken over average period of 4 Year 3 Months, then the linear and angular measurements were carried out with 11 itemized lists. Autocad Rl4 application program was utilized to draw their appearance, measure and compare their lateral area. As a result of study, conclusions were made as follows; 1. Mandibular body length (gonion-menton) tended to increase in order of CIII, CI and CII, and Mandibular body length of CIII group had a tendency to grow twice faster than that of CII group. 2. In lateral items such as Go-Me, A-Cd, B-Cp, E-F and G-H, CIII showed a significant increase on the year-average quantity and rate of the growth, and especially apparent difference was observed in CIII group rather than CII group. 3. For the 4 Year 3 Months period, the year-average growth quantity of lateral area of the mandible was $1.0cm^2$ for Class I, $0.8cm^2$ for Class II and $1.4cm^2$ for Class III, which corresponds to $11.9\%,\;11.8\%\;and\;20.3\%$ of growth ratio respectively. Thus, growth ratio almost 2 times more than other groups was observed in group CIII while growth ratio between group CI and CII has little difference. 4. Considering the results as above, it can be proposed that the difference in size of the mandible between groups is caused by the difference in the growth rate and growth quantity of the mandible, which generated in the middle of growth, rather than the difference in size of congenital Jaw-bone.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.629-639
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• 2018

In this study, the application of the single beam echosounder and multi beam echosounder was analyzed for the Youngsan river, from the Juksanbo to the Juksan bridge, length of 840m, width 230m and area $0.16km^2$. A single beam echosounder and a multi beam echosounder are mounted on an USV (Unmanned Surface Vessel), and each data is acquired. Then, TIN (Triangular Irregular Network) is created and the grid depth of 10m intervals is extracted. The grid depth of the single beam echo sounder and the grid depth of the multi beam echo sounder were overlapped to compare the two data. As a result of analysis using 5,024 data, the mean depth difference was 0.0319m and the standard deviation was 2.4095m. The river bed shape was similar to each other. If the multi-beam echo sounder is regarded as the standard, the volume difference of the stream is $161,882m^3$. With a multi-beam echo sounder installed, the operating distance increased by approximately 55% to 4595.85m, and the operating time increased by approximately 59% to approximately 47%.

• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.86-92
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• 2020

We confirmed the effects on the device performances and the charge injection characteristics of organic field-effect transistor (OFET) by selectively differently controlling the surface energies on the contact region of the substrate where the source/drain electrodes are located and the channel region between the two electrodes. When the surface energies of the channel and contact regions were kept low and increased, respectively, the field-effect mobility of the OFET devices was 0.063 ㎠/V·s, the contact resistance was 132.2 kΩ·cm, and the subthreshold swing was 0.6 V/dec. They are the results of twice and 30 times improvements compared to the pristine FET device, respectively. As the results of analyzing the interfacial trap density according to the channel length, a major reason of the improved device performances could be anticipated that the pi-pi overlapping direction of polymer semiconductor molecules and the charge injection pathway from electrode is coincided by selective surface treatment in the contact region, which finally induces the decreases of the charge trap density in the polymer semiconducting film. The selective surface treatment method for the contact region between the electrode and the polymer semiconductor used in this study has the potential to maximize the electrical performances of organic electronics by being utilized with various existing processes to lower the interface resistance.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.124-131
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• 2009

A reliable detection of regions in radiography is one of the most important task before the evaluation of defects on welded joints. The extracted features is to be classified into distinctive clusters for each segmented region. But conventional segmentation techniques give unsatisfactory results for this task due to the spatial superposition of intensity and low signal-to-ratio(SNR) in radiographic images. The usage of global or local processes not only provide the necessary noise resistance but also fail in classification of regions. In this paper, we presents an appropriate approach for segmentation of region-based indications in industrial Computed Radiography(CR) images. The geometric differences between welded and non-welded area which is generated on radiography as the representative regions(background, thickness, middle and welded region in steel tube image) have constructed the hierarchical structure. Although this structure is contaminated by noise, the scheme between regions can be selected by the help of local clustering based on distinctive geometric property of each region. Because of the geometric nature of the considered region and so that the region is selected layer by layer, and that the real class represents the boundary between regions, the vertical and horizontal clustering process in each layer must be judicious. In order to show the effectiveness of this approach, a comparative experiment of various segmentation method is performed on industrial steel tube CR images.