• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.32 no.3
• /
• pp.170-179
• /
• 2020

Tidal asymmetry would occur owing to shallow water tides at the Western Coast of macro tidal area. Especially, as ebb dominance of Mokpo coastal zone is known as the most prominent in Korea, it had been studied by domestic researchers. The cause of ebb dominance in Mokpo area is considered due to extensive inter-tidal zone in Muan Bay, and this has been studied based on amplification ratio, relative phase and skewness of tide/tidal flow curves in order to analyze qualitative tidal asymmetry. Furthermore, it was possible to figure out tidal characteristics with the difference of tidal amplitude and phase with Mokpo Harbor by observing the tide for 15 days in Muan Bay, which showed 40 minutes shorter ebbing time than at Mokpo Harbor. In addition, tidal flow prediction data in Mokpo North Harbor and Mokpo-Gu were analyzed. Meanwhile, the basis regarding qualitative interpretation of bed sediment and suspended sediment was provided by examining the qualitative changes in tidal asymmetry for spring-neap tidal cycle through the PCA/SWA indices. In addition, by examining long-term changes of ebb dominance in Mokpo Port, tidal characteristics of the past, present and future in this area, which is related to tidal asymmetry, is also provided.

• The Korean Journal of Nuclear Medicine
• /
• v.25 no.2
• /
• pp.192-199
• /
• 1991

Peripheral arterial disease, because of it's significant and prolonged morbidity and related mortality is a major medical and surgical problem. Contrast angiogram remains the essential standard for the anatomic demonstration of disease. It does not, however, provide data suitable for quantification or any evaluation of the microcirculation. For these reasons, radionuclide studies are playing an increasingly important role by not only confirming the diagnosis and offering objective data on the physiologic significance of anatomic lesions, but by offering prognosis of healing and prediction of therapeutic results. In addition, radionuclide procedures offer means to safely and repeatedly monitor response to therapy and long term follow up. The object of this study was to evaluate the clinical availability of $^{201}T1$ perfusion scan in patients with peripheral arterial diseases. We performed $^{201}T1$ perfusion scans in patients with five Buerger' s disease (10 legs), six DM gangrenes (12 legs) and classified three perfusion pattern groups. Finally we compared treatment modalities among each groups and compaired T1-201 perfusion scan findings with angiographic findings in six patients with Buerger's disease. The results were as follows: 1) Seven legs showed increased perfusion in stress image and normal or increased perfusion in resting image (type 1). Six legs showed decreased perfusion in stress image and improved in resting image (type II). Of total 13 legs, only 1 leg needed to amputation. 2) Three legs showed decreased perfusion in stress and resting image (type III), and subsequently all cases were received surgical amputation. 3) In six Buerger's disease patients, there were disagreements in two patients (2 legs) between $^{201}T1$ scan and angiography, in which angiograms were normal but $^{201}T1$ scans showed 'type II' perfusion patterns.

• Journal of the Korean Institute of Gas
• /
• v.22 no.2
• /
• pp.34-45
• /
• 2018

The cleat system in coalbed methane (CBM) reservoirs is generally occupied by water which liberated during the coalification process, and behavior of water have influence on CBM production performance. Therefore, it is essential to investigate the effect of the water saturation to operate the degasification process and predict the CBM production performance properly. In this study, type curve analyses were performed on CBM reservoirs under various water saturation to improve the prediction of production performance. A CBM reservoir models with fully-, modestly-, and undersaturated reservoir were built to get production data using GEM by CMG Ltd., and the data were matched with Fetkovich, Palacio-Blasingame(P-B), and Agarwal-Gardner (A-G) type curve. The results showed that undersaturated reservoir was successfully matched by A-G type curve, while the Fetkovich type curve was inappropriate for matching in the late time. The modestly saturated model could be almost corresponded with all the type curve methods at late production period. For the fully saturated model, after peak production had been reached, both P-B and A-G methods showed a proper match to the reservoir production data without long-term production period. Based on the results, merit and demerit of each type curve under specific water saturation were analyzed and listed. Therefore, it is believed that the production data analysis with proper type curve model considering water saturation can be performed to predict accurate production performance.

• Korean Journal of Head & Neck Oncology
• /
• v.26 no.1
• /
• pp.3-8
• /
• 2010

Background : Though papillary microcarcinoma(PMC) of thyroid gland is known to have very favorable long-term prognosis, the recurrence in the neck and distant metastasis have been often reported. The predictive factors of node metastasis and tumor recurrence in clinical course were investigated to define surgical decision or guidelines in surgery of papillary microcarcinoma. Methods : The authors conducted a retrospective analysis of 216 patients of PMC treated with surgery at Department of Surgery, Busan Paik Hospital for the period from 1997 to 2007. Of these patients, 58 cases showing cervical lymph node metastasis at initial surgery were studied. Results : In overall 216 patients, the sex ratio of male to female was 1 : 9.3(male 21, female 195 cases), the mean age at the time of diagnosis was 44.7 years and the median tumor size was 6.61mm. Neck lymph node metastasis was found in 58 patients(26.9%), thyroid capsular invasion was 56 cases(25.9%), multifocality and bilaterality were found in 32(14.8%) and 29 cases(13.4%), respectively. Through statistical analysis, sex, capsular invasion, ETE, and tumor size(>5mm) were considered to be predictive factors of cervical lymph nodes metastasis. Of them, capsular invasion was the most predictive indicator of cervical lymph node metastasis on multivariate analysis. Nodal recurrence was observed in 6 of 58 patients of node positive at initial surgery. Conclusion : The cervical lymph node metastasis is known to be a risk factor of prognosis in PMC of thyroid gland. The results of this study showed four statistically significant independent predictive factors of cervical lymph node metastasis in PMC : capsular invasion, tumor size(>5mm), ETE, and sex. On multivariate analysis, capsular invasion was a great influencing factor in prediction of lymph node metastasis. Basically, patients who has predictive factors of cervical lymph node metastasis should have a thorough investigation, and close surveillance for nodal status is required in follow-up.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.6
• /
• pp.261-271
• /
• 2003

A condition evaluation procedure for the pavement foundations using multi-load level Falling Weight Deflectometer(FWD) deflections is presented in this paper. A dynamic finite element program incorporating a stress-dependent material model, was used to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical responses, such as stresses and strains in base and subgrade layers, have been established. FWD deflection data, Dynamic Cone Penetrometer(UP) data, and repeated load resilient modulus testing results used in developing this procedure were collected from the Long Term Pavement Performance (LTPP) and North Carolina Department of Transportation (NCDOT) database. Research effort focused on investigation of the effect of the FWD load level on the condition evaluation procedures. The results indicate that the proposed procedure can estimate the pavement foundation conditions. It is also found that structurally adjusted Base Damage Index (BDI) and Base Curvature Index (BCI) are good indicators for the prediction of stiffness characteristics of aggregate base and subgrade respectively. A FWD test with a load of 66.7 kN or less does not improve the accuracy of this procedure. Results from the study for the nonlinear behavior of a pavement foundations indicate that the deflection ratio obtained from multi-load level deflections can predict the type and quality of the pavement foundation materials.

• Journal of the Korean earth science society
• /
• v.41 no.1
• /
• pp.31-39
• /
• 2020

Cheonji, the largest caldera lake in Asia, is located at the summit of Baekdu Mountain. Cheonji is covered with snow and ice for about six months of the year due to its high altitude and its surrounding environment. Since most of the sources of water are from groundwater, the water temperature is closely related to the volcanic activity. However, in the 2000s, many volcanic activities have been monitored on the mountain. In this study, we analyzed the dimension of ice produced during winter in Baekdu Mountain using Sentinel-1 satellite image data provided by the European Space Agency (ESA). In order to calculate the dimension of ice from the backscatter image of the Sentinel-1 satellite, 20 Gray-Level Co-occurrence Matrix (GLCM) layers were generated from two polarization images using texture analysis. The method used in calculating the area was utilized with the Support Vector Machine (SVM) algorithm to classify the GLCM layer which is to calculate the dimension of ice in the image. Also, the calculated area was correlated with temperature data obtained from Samjiyeon weather station. This study could be used as a basis for suggesting an alternative to the new method of calculating the area of ice before using a long-term time series analysis on a full scale.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.10 no.1
• /
• pp.69-78
• /
• 2005

ARCO and TAO data which supply three dimensional global ocean information are assimilated to the background field from a general circulation model, MOM3. Using a variational Analysis using Filter (VAF), which is a spatial variational filter designed to reduce computational time and space efficiently and economically, observed ARGO and TAO data are assimilated to the OGCM-generated background sea temperature for the generation of initial condition of the model. For the assessment of the assimilation impact, a comparative experiment has been done by integrating the model from different intial conditions: one from ARGO-, TAO-data assimilated initial condition and the other from background state without assimilation. The assimilated analysis field not only depicts major oceanic features more realistically but also reduces several systematic model bias that appear in every current OGCMs experiments. From the 10-month of model integrations with and without assimilated initial conditions, it is found that the major assimilated characteristics in sea temperature appeared in the initial field remain persistently throughout the integration. Such implies that the assimilated characteristics of the reduced sea temperature bias is to last in the integration without rapid restoration to the non-assimilated OGCM integration state by dispersing mass field in the form of internal gravity waves. From our analysis, it is concluded that the data assimilation method adapted in this study to MOM3 is reasonable and applicable with dynamical consistency. The success in generating initial condition with ARGO and TAO data assimilation has significant implication upon the prediction of the long-term climate and weather using ocean-atmosphere coupled model.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.31 no.6
• /
• pp.450-457
• /
• 2019

Sedimentation is a common problem for river ports. But its intensity depends on the rate of sedimentation, channel shape and size, hydrodynamic behavior of the river and the importance of the port. High sedimentation rate in Yangon River has become one major issue for Myanmar as her largest port is located on the Yangon riverbank. As a result of the high sedimentation rate, shallow water area near the confluence of Yangon River, Pazundaung Creek, and Bago River keeps blocking the navigation channel to the Yangon Port, which also limits the size of vessel calling to Yangon Port. Therefore, studies to understand sediment transport process in Yangon River are required because the economic development of Myanmar highly relies on the Yangon Port. This paper aims to calculate the sediment transport and to predict the riverbed elevation changes in Yangon River by using Bagnold (1966) theory. Calculation result shows that huge difference can be found in the bed load transport between the rainy season and dry season in Yangon River, and thus the sedimentation problem would become more severe in the dry season when the transported sediments are reduced. The estimated sedimentation rate in dry season indicates that the rate of riverbed level rise near the Yangon Port area is about 0.063 m per year, which would lead to approximately 3.15 m rise in the riverbed level in next 50 yrs, considering the same workload of dredging to maintain the navigation channel.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.5B
• /
• pp.405-414
• /
• 2011

The adaptive network-based fuzzy inference system (ANFIS) which had a success for time series prediction and system control was applied for modeling the hourly runoff in the Gapcheon watershed. The ANFIS used the antecedent rainfall and runoff as the input. The ANFIS was trained by varying the various simulation factors such as mean areal rainfall estimation, the number of input variables, the type of membership function and the number of membership function. The root mean square error (RMSE), mean peak runoff error (PE), and mean peak time error (TE) were used for validating the ANFIS simulation. The ANFIS predicted runoff was in good agreement with the measured runoff and the applicability of ANFIS for modelling the hourly runoff appeared to be good. The forecasting ability of ANFIS up to the maximum 8 lead hour was investigated by applying the different input structure to ANFIS model. The accuracy of ANFIS for predicting the hourly runoff was reduced as the forecasting lead hours increased. The long-term predictability of ANFIS for forecasting the hourly runoff at longer lead hours appeared to be limited. The ANFIS might be useful for modeling the hourly runoff and has an advantage over the physically based models because the model construction of ANFIS based on only input and output data is relatively simple.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.7
• /
• pp.754-759
• /
• 2015

Nowadays, short distance communication systems with low power energy (LPE) are developed for identification and monitoring of site identification of vessel crews and passengers (SIVCP). LPE communication modules, such as Bluetooth low energy (BLE) and Zigbee, are used for short distance communications with LPE. These modules enable 1:N communications and their popularity is growing since the modules can be mounted on movable objects, such as mobile devices and human body. When these modules are used, the important factor that affects their operation time and design are the capacity and size of battery. Therefore, they must be made as small as possible, and the battery should be selected to be slightly smaller than the module. In this study, we calculate the theoretical life of batteries used in SIVCP BLE modules using data sheet and discharge characteristic graph under the condition of a 1/250 transmission-ratio (TR). We thus calculate experimental life by measuring transmission current for the same TR, and low speed mode current for a 1/5000 TR and measure long-term experimental life using 1/25 TR for days. Through these experiments, we verify experimental methods for the prediction and extension of battery life that would enable us to select appropriate sizes of batteries based on vessel usage and passenger types. The selections of the module TR and battery size are important factors affecting the cost reduction of module design, the battery maintenance, and passenger convenience.