• Journal of KIISE:Databases
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• v.37 no.2
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• pp.71-81
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• 2010

The problem of finding clusters is widely used in numerous applications, such as pattern recognition, image analysis, market analysis. The important factors that decide cluster quality are the similarity measure and the number of attributes. Similarity measures should be defined with respect to the data types. Existing similarity measures are well applicable to numerical attribute values. However, those measures do not work well when the data is described by categorical attributes, that is, when no inherent similarity measure between values. In high dimensional spaces, conventional clustering algorithms tend to break down because of sparsity of data points. To overcome this difficulty, a subspace clustering approach has been proposed. It is based on the observation that different clusters may exist in different subspaces. In this paper, we propose a new similarity measure for clustering of high dimensional categorical data. The measure is defined based on the fact that a good clustering is one where each cluster should have certain information that can distinguish it with other clusters. We also try to capture on the attribute dependencies. This study is meaningful because there has been no method to use both of them. Experimental results on real datasets show clusters obtained by our proposed similarity measure are good enough with respect to clustering accuracy.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.65-71
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• 2015

Red Tide phenomenon which happens in the southern coast of Korea gives massive damage to the fishermen who run fish farms and thereby a lot of efforts to prevent damage are made from various angles. In particular, red tide monitoring with satellite imagery can make it possible to obtain the occurrence data of red tide throughout the whole areas of the sea, which helps provide important information for establishing the preventive plans of disasters. In this regard, this study selected the South Sea of Gyeongnam Province with a view to suggesting the monitoring results with regard to the spread and reduction of the Red Tide in the middle of the day by using the GOCI Images of COMS. With this intention, it selected the region in the South Sea of Gyeongnam Province. The study results of analysis on the GOCI image data for the years of 2013(Aug. 12) and 2014 (Sep. 11) are as follows: the pattern of the Red Tide in the region of the South Sea occurred in the southern sea area of Geoje-do in the morning. It gradually spread and showed a gradual decline after reaching the top at 1 PM. In addition, in terms of the tide movement in the middle of the day, Red Tide began in the southern sea area and moved to the west, and moved to the east again at noon. It is judged that additional study on many factors such as the characteristics of the future Red-tide organisms, tidal currents, amount of sunshine, and water temperature is needed, but it is estimated that Red Tide movement monitoring with GOCI images would provide very crucial information for predicting the spread and movement of the Red Tide to protect and manage the Red Tide disasters.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.599-610
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• 2005

Purpose: The success of the bonding between electroformed gold and ceramic is dependent on the surface treatment of the pure gold coping. The purpose of this study was to evaluate the bonding strength between the electroformed gold and ceramic with varying surface treatment. Materials and methods: A total of 32 disks,8 were using conventional ceramometal alloy, 24 were using electroforming technique as recommended by manufacturer, were prepared. 24 electroformed disks were divided 3 groups according to surface treatment, i.e. 50 microns aluminium oxide sandblasting(GES-Sand), gold bonder treatment(GES-Bond) and $Rocatec^{TM}$ system(GES-Rocatec). For control group of conventional alloy 50 microns aluminium oxide treatment was done(V-Supragold). Energy dispersive x-ray analysis and scanning electron microscope image were observed. Using universal testing machine, shear bond strength and bonding failure mode at metal-porcelain interface were measured. Results and Conclusion: The following conclusions were drawn: 1. In the energy dispersive x-ray analysis, the Au was main component in electroformed gold(99.9wt%). After surface treatment, a little amount of $Al_2O_3(2.4wt%)$ were found in GES-Sand, and $SiO_2(4wt%)$ in GES-Bond. In GES-Rocatec, however, a large amount of $SiO_2(17.4wt%)$ were found. 2. In the scanning electron microscopy, similar pattern of surface irregu larities were observed in V-Supragold and GES-Sand. In GES-Bond, surface irregularities were increased and globular ceramic particles were observed. In GES-Rocatec, a large amount of silica particles attached to metal surface with increased surface irregularities were observed. 3. The mean shear bond strength values(MPa) in order were $22.9{\pm}3.7(V-Supragold),\;22.1{\pm}3.8(GES-Bond),\;20.1{\pm}2.8(GES-Rocatec)\;and\;13.0{\pm}1.4(GES-Sand)$. There was no significant difference between V-Supragold, GES-Bond, and GES-Rocatec. (P>0.05) 4. Most bonding failures modes were adhesive type in GES-Sand. However, in V-Supragold, GES-Bond and GES-Rocatec, cohesive and combination failures were commonly observed. From the result, with proper surface treatment method electroformed gold may have enough strength compare to conventional ceramometal alloy.

• Journal of the Korean association of regional geographers
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• v.7 no.2
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• pp.82-96
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• 2001

The purpose of this study is to investigate the wise use and the management of intertidal environment. For tills purpose, we selected the Kanghwa island mudflat which is one of the most important intertidal region in Korea peninsula. The main research method is surface sediment and several map analysis. The results are as follows. (1) The study area is worldwide coastal wetland in view of ecology and geomorphology. But most of the salt marsh has been reclaimed since Japanese colonial period, the study area is mainly composed of mudflat. (2) The mean tidal regime of study area is 7.3m. From this tidal regime, the study area is subdivided into four distinct areas: the high intertidal area the middle intertidal area the low intertidal area and the shallow sea area terrestrial area near mudflat. (3) The mean particle size of surface sediment is sand 41.5%, silt 47.3%, clay 11.2%. This particle size pattern indicates the ecological characteristics of surface sediment of the study area. The proportion of clay is increasing to the open sea. (5) The pursuit of the wise use and the management must be implemented by the consideration of not only ecologic and sedimentary characteristics but also of the eco-tour site plan. And the entire use and management subject is different in each area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.284-295
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• 2019

Celebrities form a dominant culture of one era and are cultivating influence to lead new fashion. Domestic women celebrities attending Seoul Fashion Week build their image as a fashion leader by exposing their own fashion aesthetics to the public. This promotes PR and sales of the brand of fashion designers in the collection. This study considers the fashion trends of women celebrities by analyzing the fashion style of women celebrities in Seoul Collection over the recent five years. The results of this study on contents analysis are as follows. First, straight silhouettes, achromatic colors, and an absence of a pattern or decoration comprised a high proportion. Celebrities preferred a modern and minimal style. Second, they preferred a feminine style that shows traditional feminine beauty through slim and princess silhouettes, one-piece dress or skirts, soft materials, and decorations with ruffles. In addition, as a matching jacket on one-piece dresses also appeared, it showed that celebrities attempted to change the chic feminine style with masculine beauty. Third, boxy silhouettes, multi-color mixed with colorful colors, graphic or lettering patterns, glittering materials and lots of details comprised a high proportion. This means celebrities pursue a maximal style that reveals their strong presence as fashion leaders.

• Journal of Service Research and Studies
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• v.11 no.2
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• pp.21-36
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• 2021

This study investigated the means-end chain theory more concretely through the APT hard laddering technique. This is carrying out a questionnaire survey targeting users by hair salon type, and the items drawn from the qualitative laddering technique are applied. The technique is a comparative analysis of each attribute, consequences, and value item by analyzing each step's questions. The results are as follows. First, hairdresser's ability, acceptance of individual-customized opinions, and cheap price were the most mentioned items in the selection attributes. As for the consequences items, image transformation, neatness, novelty, and psychological stability were drawn in order. The items indicated as important among the value items were satisfaction, followed by happiness, confidence, beauty, and bond. Second, the remarkable selection attributes, irrelevant of hair salon type, was revealed as hairdresser's ability and the key values pursued when using a hair salon were drawn as satisfaction, confidence, and beauty. From this result, it was found that meeting the desire of consumers using hair salons can be linked with ultimately pursued values. It was also verified that partial differences were shown by hair salon type and this meant that consumers' desire and expected benefits were different by hair salon type. Although this study drew value perception through comparison with hair salon types based on the means-end chain theory, it was confirmed that the most important selection attribute was hairdresser's ability and they select and use hair salons to gain satisfaction and confidence.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1115-1122
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• 2023

This study aimed to present reasonable reception bandwidth application standards for the purpose of suppressing metal objects during MRI examinations. For this purpose, T2 contrast images were acquired using high-speed spin echo technology on a phantom made of screws for spinal surgery, and metal objects were detected. In addition, images were obtained by increasing the reception bandwidth from 100 Hz/PX to 800 Hz/PX by 100 Hz/PX. The metal artifacts were determined as the sum of the areas of the signal attenuation area and the signal accumulation area. In addition, Pearson correlation analysis was performed to analyze the pattern of metal artifacts according to imaging variables. As a result, the signal accumulation area did not change significantly as the reception bandwidth increased (p>0.05), but the signal loss area and the area of metal artifacts decreased as the reception bandwidth increased (p<0.05). Interestingly, the area of metal objects decreased to a maximum in the section where the reception bandwidth was increased from 100 Hz/PX to 200 Hz/PX, consistent with the section where the echo spacing was reduced to a maximum due to the increase in reception bandwidth. In addition, the correlation analysis results also showed that the eco spacing was more related to the signal attenuation area and the area of metal objects than to the reception bandwidth. Therefore, if the reception bandwidth is increased for the purpose of reducing metal objects, it is reasonable to set it based on a value that minimizes the echo spacing in consideration of image quality factors.

• Journal of the Korean Chemical Society
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• v.60 no.3
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• pp.203-214
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• 2016

The purpose of this study was to investigate brain activation pattern and functional connectivity during convergence thinking based creative problem solving and chemistry problem solving to identify characteristic convergence thinking that is backbone of creative problem solving using functional magnetic resonance imaging(fMRI). A fMRI paradaigm inducing convergence thinking and chemistry problem solving was developed and adjusted on 17 highschool students, and brain activation image during task was analyzed. According to the results, superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus, medial frontal gyrus, cingulate gyrus, precuneus and caudate nucleus body in left hemisphere and cuneus and caudate nucleus body in right hemisphere were significantly activated during convergence thinking. The other hand, middle frontal gyrus, medial frontal gyrus and caudate nucleus in left hemisphere and middle frontal gyrus, lingual gyrus, caudate nucleus, thalamus and culmen of cerebellum in right hemisphere were significantly activated during chemistry problem solving. As results of analysis functional connectivity, all of areas activated during convergence thinking were functionaly connected, whereas scanty connectivity of chemistry problem solving between right middle frontal gyrus, bilateral nucleus caudate tail and culmen. The results show that logical thinking, working memory, planning, imaging, languge based thinking and learning motivation were induced during convergence thinking and these functions and regions were synchronized intimately. Whereas, logical thinking and inducing learning motivation functioning during chemistry problem solving were not synchronized. These results provide concrete information about convergence thinking.

• Journal of Intelligence and Information Systems
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• v.26 no.2
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• pp.131-145
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• 2020

In line with the trend of industrial innovation, IoT technology utilized in a variety of fields is emerging as a key element in creation of new business models and the provision of user-friendly services through the combination of big data. The accumulated data from devices with the Internet-of-Things (IoT) is being used in many ways to build a convenience-based smart system as it can provide customized intelligent systems through user environment and pattern analysis. Recently, it has been applied to innovation in the public domain and has been using it for smart city and smart transportation, such as solving traffic and crime problems using CCTV. In particular, it is necessary to comprehensively consider the easiness of securing real-time service data and the stability of security when planning underground services or establishing movement amount control information system to enhance citizens' or commuters' convenience in circumstances with the congestion of public transportation such as subways, urban railways, etc. However, previous studies that utilize image data have limitations in reducing the performance of object detection under private issue and abnormal conditions. The IoT device-based sensor data used in this study is free from private issue because it does not require identification for individuals, and can be effectively utilized to build intelligent public services for unspecified people. Especially, sensor data stored by the IoT device need not be identified to an individual, and can be effectively utilized for constructing intelligent public services for many and unspecified people as data free form private issue. We utilize the IoT-based infrared sensor devices for an intelligent pedestrian tracking system in metro service which many people use on a daily basis and temperature data measured by sensors are therein transmitted in real time. The experimental environment for collecting data detected in real time from sensors was established for the equally-spaced midpoints of 4×4 upper parts in the ceiling of subway entrances where the actual movement amount of passengers is high, and it measured the temperature change for objects entering and leaving the detection spots. The measured data have gone through a preprocessing in which the reference values for 16 different areas are set and the difference values between the temperatures in 16 distinct areas and their reference values per unit of time are calculated. This corresponds to the methodology that maximizes movement within the detection area. In addition, the size of the data was increased by 10 times in order to more sensitively reflect the difference in temperature by area. For example, if the temperature data collected from the sensor at a given time were 28.5℃, the data analysis was conducted by changing the value to 285. As above, the data collected from sensors have the characteristics of time series data and image data with 4×4 resolution. Reflecting the characteristics of the measured, preprocessed data, we finally propose a hybrid algorithm that combines CNN in superior performance for image classification and LSTM, especially suitable for analyzing time series data, as referred to CNN-LSTM (Convolutional Neural Network-Long Short Term Memory). In the study, the CNN-LSTM algorithm is used to predict the number of passing persons in one of 4×4 detection areas. We verified the validation of the proposed model by taking performance comparison with other artificial intelligence algorithms such as Multi-Layer Perceptron (MLP), Long Short Term Memory (LSTM) and RNN-LSTM (Recurrent Neural Network-Long Short Term Memory). As a result of the experiment, proposed CNN-LSTM hybrid model compared to MLP, LSTM and RNN-LSTM has the best predictive performance. By utilizing the proposed devices and models, it is expected various metro services will be provided with no illegal issue about the personal information such as real-time monitoring of public transport facilities and emergency situation response services on the basis of congestion. However, the data have been collected by selecting one side of the entrances as the subject of analysis, and the data collected for a short period of time have been applied to the prediction. There exists the limitation that the verification of application in other environments needs to be carried out. In the future, it is expected that more reliability will be provided for the proposed model if experimental data is sufficiently collected in various environments or if learning data is further configured by measuring data in other sensors.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.375-390
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• 2009

Statement of problem: Implant supported overdenture is accepted widely as a way to restore edentulous ridge providing better retention and support of dentures. Various types of attachment for overdenture have been developed. Purpose: The purpose of this study was to investigate the influence of attachment type in implant overdentures on the biomechanical stress distribution in the surrounding bone, prosthesis and interface between implant and bone. Material and methods: Finite element analysis method was used. Average CT image of mandibular body(Digital $Korea^{(R)}$, KISTI, Korea) was used to produce a mandibular model. Overdentures were placed instead of mandibular teeth and 2mm of mucosa was inserted between the overdenture and mandible. Two implants($USII^{(R)}$, Osstem, Korea) were placed at both cuspid area and 4 types of overdenture were fabricated ; ball and socket, Locator, magnet and bar type. Load was applied on the from second premolar to second molar tooth area. 6 times of finite element analyses were performed according to the direction of the force $90^{\circ}$, $45^{\circ}$, $0^{\circ}$ and unilateral or bilateral force applied. The stress at interface between implants and bone, and prosthesis and the bone around implants ware compared using von Mises stress. The results were explained with color coded graphs based on the equivalent stress to distinguish the force distribution pattern and the site of maximum stress concentration. Results: Unilateral loading showed that connection area between implant fixture and bar generated maximum stress in bar type overdentures. Bar type produced 100 Mpa which means the most among 4 types of attachments. Bilateral loading, however, showed that bar type was more stable than other implants(magnet, ball and socket). 26 Mpa of bar type was about a half of other types on overdenture under $90^{\circ}$ bilateral loading. Conclusions: In any directions of stress, bar type was proved to be the most vulnerable type in both implants and overdentures. Interface stress did not show any significant difference in stress distribution pattern.