• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.6
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• pp.683-690
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• 2006

Reducing power consumption to extend network lifetime is one of the most important challenges in designing wireless sensor networks. One promising approach to conserving system energy is to keep only a minimal number of sensors active and put others into low-powered sleep mode, while the active sensors can maintain a connected covet set for the target area. The problem of computing such minimum working sensor set is NP-hard. In this paper, a centralized Voronoi tessellation (CVT) based approximate algorithm is proposed to construct the near optimal cover set. When sensor's communication radius is at least twice of its sensing radius, the covet set is connected at the same time; In case of sensor's communication radius is smaller than twice of its sensing radius, a connection scheme is proposed to calculate the assistant nodes needed for constructing the connectivity of the cover set. Finally, the performance of the proposed algorithm is evaluated through theoretical analysis and extensive numerical experiments. Experimental results show that the proposed algorithm outperforms the greedy algorithm in terms of the runtime and the size of the constructed connected cover set.

• Korean Journal of Remote Sensing
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• v.38 no.5_2
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• pp.793-810
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• 2022

Synthetic Aperture Radar (SAR) is considered to be suitable for near real-time inundation monitoring. The distinctly different intensity between water and land makes it adequate for waterbody detection, but the intrinsic speckle noise and variable intensity of SAR images decrease the accuracy of waterbody detection. In this study, we suggest two modules, named 'morphology module' and 'edge-enhanced module', which are the combinations of pooling layers and convolutional layers, improving the accuracy of waterbody detection. The morphology module is composed of min-pooling layers and max-pooling layers, which shows the effect of morphological transformation. The edge-enhanced module is composed of convolution layers, which has the fixed weights of the traditional edge detection algorithm. After comparing the accuracy of various versions of each module for U-Net, we found that the optimal combination is the case that the morphology module of min-pooling and successive layers of min-pooling and max-pooling, and the edge-enhanced module of Scharr filter were the inputs of conv9. This morphologic and edge-enhanced U-Net improved the F1-score by 9.81% than the original U-Net. Qualitative inspection showed that our model has capability of detecting small-sized waterbody and detailed edge of water, which are the distinct advancement of the model presented in this research, compared to the original U-Net.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.67-67
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• 2003

It is crucial to minimize setup errors of a cancer treatment machine using a high energy and to perform precise radiation therapy. Usually, port film has been used for verifying errors. The Korea Cancer Center Hospital (KCCH) has manufactured digital electronic portal imaging device (EPID) system to verify treatment machine errors as a Quality Assurance (Q.A) tool. This EPID was consisted of a metal/fluorescent screen, 45$^{\circ}$ mirror, a camera and an image grabber and could display the portal image with near real time KIRAMS has also made the acrylic phantom that has lead line of 1mm width for ligh/radiation field congruence verification and reference points phantom for using as an isocenter on portal image. We acquired portal images of 10$\times$10cm field size with this phantom by EPID and portal film rotating treatment head by 0.3$^{\circ}$, 0.6$^{\circ}$ and 0.9$^{\circ}$. To check field size, we acquired portal images with 18$\times$18cm, 19$\times$19cm and 20$\times$20cm field size with collimator angle 0$^{\circ}$ and 0.5$^{\circ}$ individually. We have performed Flatness comparison by displaying the line intensity from EPID and film images. The 0.6$^{\circ}$ shift of collimator angle was easily observed by edge detection of irradiated field size on EPID image. To the extent of one pixel (0.76mm) difference could be detected. We also have measured field size by finding optimal threshold value, finding isocenter, finding field edge and gauging distance between isocenter and edge. This EPID system could be used as a Q.A tool for checking field size, light/radiation congruence and flatness with a developed video based EPID.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.1
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• pp.28-37
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• 2022

Pregnancy requires an important interpretation of thyroid function tests. The presence of anti-thyroid antibodies and viral infectious agents affect the health of both the fetus and the mother. Hence, a selective evaluation of thyroid function in pregnancy is required. This study is a retrospective cross-sectional survey to examine the correlation between thyroid hormones and viral infections during pregnancy. The results showed that the triiodothyronine (T3) decreased with increasing age, especially in the hepatitis C virus (HCV)-positive group (P<0.01). In addition, although negative for the human immunodeficiency virus (HIV), thyroxine (FT4) showed a significant increase in near-threshold or twin pregnant women (P<0.05). The thyroid stimulating hormone (TSH) was highly distributed at the age of 30, and there was no statistically significant correlation with other viral infection factors. In addition, as a result of dividing and analyzing the result of TSH by the quantiles, FT4 and T3 showed a positive correlation but showed a negative correlation with TSH (P<0.05). Therefore, the evaluation of prenatal thyroid screening during pregnancy and viral infection factors should reflect the time of pregnancy, exposure to infection, and the quantitative values. Adequate thyroid hormone and viral infections availability is important for an uncomplicated pregnancy and optimal fetal development.

• Journal of Intelligence and Information Systems
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• v.16 no.3
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• pp.147-161
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• 2010

As broadcasting and communication are converged recently, communication is jointed to TV. TV viewing has brought about many changes. The IPTV (Internet Protocol Television) provides information service, movie contents, broadcast, etc. through internet with live programs + VOD (Video on demand) jointed. Using communication network, it becomes an issue of new business. In addition, new technical issues have been created by imaging technology for the service, networking technology without video cuts, security technologies to protect copyright, etc. Through this IPTV network, users can watch their desired programs when they want. However, IPTV has difficulties in search approach, menu approach, or finding programs. Menu approach spends a lot of time in approaching programs desired. Search approach can't be found when title, genre, name of actors, etc. are not known. In addition, inserting letters through remote control have problems. However, the bigger problem is that many times users are not usually ware of the services they use. Thus, to resolve difficulties when selecting VOD service in IPTV, a personalized service is recommended, which enhance users' satisfaction and use your time, efficiently. This paper provides appropriate programs which are fit to individuals not to save time in order to solve IPTV's shortcomings through filtering and recommendation-related system. The proposed recommendation system collects TV program information, the user's preferred program genres and detailed genre, channel, watching program, and information on viewing time based on individual records of watching IPTV. To look for these kinds of similarities, similarities can be compared by using ontology for TV programs. The reason to use these is because the distance of program can be measured by the similarity comparison. TV program ontology we are using is one extracted from TV-Anytime metadata which represents semantic nature. Also, ontology expresses the contents and features in figures. Through world net, vocabulary similarity is determined. All the words described on the programs are expanded into upper and lower classes for word similarity decision. The average of described key words was measured. The criterion of distance calculated ties similar programs through K-medoids dividing method. K-medoids dividing method is a dividing way to divide classified groups into ones with similar characteristics. This K-medoids method sets K-unit representative objects. Here, distance from representative object sets temporary distance and colonize it. Through algorithm, when the initial n-unit objects are tried to be divided into K-units. The optimal object must be found through repeated trials after selecting representative object temporarily. Through this course, similar programs must be colonized. Selecting programs through group analysis, weight should be given to the recommendation. The way to provide weight with recommendation is as the follows. When each group recommends programs, similar programs near representative objects will be recommended to users. The formula to calculate the distance is same as measure similar distance. It will be a basic figure which determines the rankings of recommended programs. Weight is used to calculate the number of watching lists. As the more programs are, the higher weight will be loaded. This is defined as cluster weight. Through this, sub-TV programs which are representative of the groups must be selected. The final TV programs ranks must be determined. However, the group-representative TV programs include errors. Therefore, weights must be added to TV program viewing preference. They must determine the finalranks.Based on this, our customers prefer proposed to recommend contents. So, based on the proposed method this paper suggested, experiment was carried out in controlled environment. Through experiment, the superiority of the proposed method is shown, compared to existing ways.

• Korean Journal of Remote Sensing
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• v.37 no.6_3
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• pp.2035-2046
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• 2021

Glacier movement speed is the most basic measurement for glacial dynamics research and is a very important indicator in predicting sea level rise due to climate change. In this study, the two-dimensional velocity measurements of Campbell Glacier located in Terra Nova Bay in East Antarctica were observed through the SAR offset tracking technique. For this purpose, domestic KOMPSAT-5 SAR satellite images taken on July 9, 2021 and August 6, 2021 were acquired. The Multi-kernel SAR offset tracking proposed through previous studies is a technique to obtain the optimal result that satisfies both resolution and precision. However, since offset tracking is repeatedly performed according to the size of the kernel, intensive computational power and time are required. Therefore, in this study, we strategically proposed a coarse-to-fine offset tracking approach. Through coarse-to-fine SAR offset tracking, it is possible to obtain a result with improved observation precision (especially, about 4 times in azimuth direction) while maintaining resolution compared to general offset tracking results. Using this proposed technique, a two-dimensional velocity measurements of Campbell Glacier were generated. As a result of analyzing the two-dimensional movement velocity image, it was observed that the grounding line of Campbell Glacier exists at approximately latitude -74.56N. The flow velocity of Campbell Glacier Tongue analyzed in this study (185-237 m/yr) increased compared to that of 1988-1989 (140-240 m/yr). And compared to the flow velocity (181-268 m/yr) in 2010-2012, the movement speed near the ground line was similar, but it was confirmed that the movement speed at the end of the Campbell Glacier Tongue decreased. However, there is a possibility that this is an error that occurs because the study result of this study is an annual rate of glacier movement that occurred for 28 days. For accurate comparison, it will be necessary to expand the data in time series and accurately calculate the annual rate. Through this study, the two-dimensional velocity measurements of the glacier were observed for the first time using the KOMPSAT-5 satellite image, a domestic X-band SAR satellite. It was confirmed that the coarse-to-fine SAR offset tracking approach of the KOMPSAT-5 SAR image is very useful for observing the two-dimensional velocity of glacier movements.

• Explosives and Blasting
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• v.30 no.2
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• pp.29-42
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• 2012

Variables influencing the free face movement due to rock blasting include the physical and mechanical properties, in particular the discontinuity characteristics, explosive type, charge weight, burden, blast-hole spacing, delay time between blast-holes or rows, stemming conditions. These variables also affects the blast vibration, air blast and size of fragmentation. For the design of surface blasting, the priority is given to the safety of nearby buildings. Therefore, blast vibration has to be controlled by analyzing the free face movement at the surface blasting sites and also blasting operation needs to be optimized to improve the fragmentation size. High-speed digital image analysis enables the analyses of the initial movement of free face of rock, stemming optimality, fragment trajectory, face movement direction and velocity as well as the optimal detonator initiation system. Even though The high-speed image analysis technique has been widely used in foreign countries, its applications can hardly be found in Korea. This thesis aims at carrying out a fundamental study for optimizing the blast design and evaluation using the high-speed digital image analysis. A series of experimentation were performed at two large surface blasting sites with the rock type of shale and granite, respectively. Emulsion and ANFO were the explosives used for the study. Based on the digital images analysis, displacement and velocity of the free face were scrutinized along with the analysis fragment size distribution. In addition, AUTODYN, 2-D FEM model, was applied to simulate detonation pressure, detonation velocity, response time for the initiation of the free face movement and face movement shape. The result show that regardless of the rock type, due to the displacement and the movement velocity have the maximum near the center of charged section the free face becomes curved like a bow. Compared with ANFO, the cases with Emulsion result in larger detonation pressure and velocity and faster reaction for the displacement initiation.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1086-1091
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• 1999

$K^+-{\beta}/{\beta}"-Al_2O_3$ in the ternary system $K_2O-MgO-Al_2O_3$ was directly synthesized by solid state reaction. The phase formation and phase relation were carefully investigated in relation to starting composition, calcining temperature and time, and dispersion medium. The optimal synthetic condition was also examined for the formation of ${\beta}"-Al_2O_3$ phase with a maximum fraction. As a composition range, the mole ratio of $K_2O$ to $Al_2O_3$ was changed from 1:5 to 1:6.2 and the amount of MgO used as a stabilizer was varied from 4.2 wt % to 6.3 wt %. The calcining temperature was selected between $1000^{\circ}C$ and $1500^{\circ}C$. At $1000^{\circ}C$, the ${\beta}/{\beta}"-Al_2O_3$ phases began to form resulted from the combining of ${\alpha}-Al_2O_3$ and $KAlO_2$ and increased with temperature rising. All of ${\alpha}-Al_2O_3$ phase disappeared to be homogenized to the ${\beta}/{\beta}"-Al_2O_3$ phase at $1200^{\circ}C$. Near the temperature at $1300^{\circ}C$, the fraction of ${\beta}"-Al_2O_3$ phase showed a maximum value with the composition of $K_{1.67}Mg_{0.67}Al_{10.33}O_{17}$. At temperatures above $1300^{\circ}C$, the fraction of ${\beta}"-Al_2O_3$ phase decreased gradually owing to $K_2O$ loss caused by a high potassium vapor pressure, and the appropriate calcining time was about 5 hours. Acetone was more effective than distilled water as a dispersion medium for milling and mixing.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.4
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• pp.26-37
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• 2015

This paper aims to review all landscaping elements of Donggwoldo by building and identify the palatial garden landscaping characteristics and landscaping methods in a bid to explore landscaping methods applicable for modern-time gardens of Korea through Succession of Tradition. The research methodology was adopted by which the palatial gardens appearing in Donggwoldo were observed according to garden elements to identify their characteristics. Garden elements in Donggwoldo include oddly shaped stones, ponds, buildings and Madang, borders and areas, and trees. Their characteristics were analyzed, and as a result they are outlined as follows. Location : Buildings in Donggwoldo were located in the optimal areas within the Myungdang (the best location), with the building sites being created by transforming the natural topography positively according to the existing topography and uses. Tree planting : The construction of the buildings involved using the existing trees. There were no specific principle and method of planting trees, and no specific criteria for choosing the kind of tree. Symmetrical planting was adopted and its is considered embracing the viewpoint of making gardens based on the expression of Yin and Yang. Strongly symbolical kinds of trees were also adopted. Bangji : it takes a nearly circular shape in palatial gardens, and such shapes represent conceptual and abstract symbols. They were also frequently used as the place of public entertainment. Pavilions : they did not take a certain standard shape. They had diverse shapes, including a triangle, square, pentagon, hexagon, and octagon and cross. Oddly shaped stones : Oddly shapes stones and stone cases were deployed mainly near the bedroom and the crow prince's residence and in the rear garden. Hwagye : it appeared mainly in the back of the bedroom, the crown prince's residence, the princess's residence, and other women's quarters. Chwibyeong : it was installed for the purpose of drawing the natural energy like a natural inlet instead of being the nature-dividing wall. Korea's garden composition method was very different from the Western and Chinese method. Overall, Chosun palatial garden style was characterized by strict and Confucian features, while the garden construction method adopted the Taoism thought. Yet, the gardens had a carefree aspect.