• Journal of radiological science and technology
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• v.15 no.2
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• pp.25-30
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• 1992

With transmitted dose through chest which has the problem of wide variations in absorption, simple film/screen combination method makes it diffucult to image lung field, mediastinum and retrocardiac areas. In order to overcome this, it is very common to use the high kilovoltage technique in diminishing the differences between high and low contrast. We have been adopting this method at department of diagnostic radiology, Seoul National University Hospital. To compare the image of it with that of low kilovoltage technique, we did radiographic tests using beans on the skin. We marked off into three anatomical categories such as lungs, mediastinum and near diaphragm, then attached a bean on a marked area at random. In order to compare with high and low, we took a radiography of high($120{\sim}140\;kVp$) and low($70{\sim}90\;kVp$) kilovoltage tehchniques, respectively at the same time. We have done experiments 320 cases. We evaluated the results of test in response to sensitivity(true positive) and specificity(true negative). In evaluating, we gave them points from 1 to 5 according to true or false. With given points by a radiologist having much experiences, we could acquire the percentage of sensitivity and specificity. The percentage made us to get the schematic table of ROC curve of those two methods. Consequently, high kilovoltage technique appeared 18% better than low kilovoltage technique for detecting beans with our apparatus.

• The Journal of Information Systems
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• v.20 no.3
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• pp.257-277
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• 2011

The current study categorizes factors of smartphone into three, using KANO model: attractive factors which cause only product satisfaction, must-be factors for dissatisfaction, and one-dimensional factors for both. Based on it, it presents a new model for the effects that smartphone factors have on satisfaction or dissatisfaction. The purpose is to theoretically explain that smartphone factors on which companies and users place a high value can actually affect satisfaction or dissatisfaction. After choosing 15 factors out of 25 which had been selected through literature study, these were divided into attractive, must-be, and one-dimensional ones. 93 out of 109 questionnaires returned were used for analysis. After frequency analysis using SPSS were conducted on the surveys, the factors were grouped, based on KANO table. The grouping results are as follows. Attractive factors include 'expansion slots for external memory, battery desorption, brand awareness, mobile banking and internet telephony'. Must-be ones include 'multi-touch, information security, entertainment, information retrieval, location based service and SNS. Finally, 'screen visibility, size of internal memory, the amount of internal memory, battery life, and response to after-sales service' are classified as one-dimensional factors. A critical finding of this paper is that since the results are different depending on the operating system of smartphones, it must be taken into consideration in studies on smartphones. The wide and rapid spread of smartphones has changed people's lifestyle as well as business environment, which forces companies to compete with each other to adapt to the changed circumstances. In this competitive system, studies on smartphone factors of satisfaction and dissatisfaction are essential for firms to establish a new strategy. From this point of view, the present paper is expected to be a basic material for enterprises not only to develop goods and services that maximize customer satisfaction and minimize dissatisfaction, but also to establish the future business strategy.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.3
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• pp.155-162
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• 2016

Observations of the damages to high-rise reinforced concrete (RC) wall building structures caused by by recent earthquakes in Chile ($M_w$ 8.8, February 2010) and New Zealand (February 2011, $M_L$ 6.3) have generally exceeded expectations. Firstly, this study estimated the seismic damage levels of 15-story RC box-type wall building structures using the analytical models calibrated by the results of a shaking table test on a 1:5 scale 10-story RC box-type wall building model. Then, the seismic fragility analysis of the prototype model was conducted by using the SAC/FEMA method and the incremental dynamic analysis (IDA). To compensate for the uncertainties and variability of ground motion and its impacts on the prototype model, in the SAC/FEMA method, a total of 61 ground motion records were selected from 20 earthquakes, with a magnitude ranging from 5.9 to 8.8 and an epicentral distance ranging from 5 to 105km. In the IDA, a total of 11 ground motion records were used based on the uniform hazard response spectrum representing a return period of 2,475 years. As a result, the probabilities that the limits of the serviceability, damage control, and collapse prevention would be exceeded were as follows: from the SAC/FEMA method: 79%, 0.3%, and 0%, respectively; and from the IDA: 57%, 1.7%, and 0%, respectively.

• Journal of Acupuncture Research
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• v.24 no.1
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• pp.127-135
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• 2007

Objectives: To evaluate the methodological quality of Korean Acupuncture Clinical trials Methods : Two independent researchers reviewed 12 protocols of Acupuncture clinical trials which were conducted in Korea 2006. Also, Survey Principal Investigator of those was conducted. We compare the results of protocol review with investigator reponses of actual practice. Quality assessment consisted of 5 items including random sequence generation, randomization method, allocation concealment, subject blinding, assessor blinding. Results : Randomization was performed using the proper procedure to insure that treatment assignment is unbiased and concealed from subjects in all clinical trials, According to protocols, 6(50%) of 12 clinical trials used computer-generated random numbers, 6(50%) remaining trials didn't describe the randomization method. Also all trials used appropriate randomization methods on the basis of the survey results: 8 trials used computer-generated random number, 2 used random table. Of 7 protocols in which allocation concealment was stated, 5(71%) reported appropriate method (Calling a central office or statisticians, Sealed opaque envelopes). However according to survey, 5(42%) of 12 trials used inappropriate allocation concealment (Keeping a master randomization list and referring to when subject entered the trial). In addition, the result of protocol review and survey response was not coincident in 5(42%) trials. Subject blinding was conducted in all except 1 clinical trials. Although 11(92%) of 12 trials were conducted using assessor blinding in actual practice, only 7(58%) reported that in protocol. Conclusion : Although randomization and blinding were conducted adequately, allocation concealment was used inadequately, Not only appropriate allocation concealment, but also every quality assessment item including randomization, blinding should be stated in more detail in protocol.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.119-127
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• 2018

The formal data used in the business is managed in a table form without normalization due to lack of understanding and application of data modeling. If the balance of the database design is destroyed, it affects the speed of response to the data query, and the data obesity becomes high. In this paper, it is investigated how data obesity improved through database design through optimized data modeling. The data query path was clearly visualized by square design through data modeling based on the relationship between object (data) and object, from the radial and task - oriented isolation design where data obesity is excessive. In terms of data obesity, the obesity degree of the current research support database was 57.2%, but it was 16.2% in the new research support database, and the data obesity degree was reducd by 40.5%. In addition, by minimizing redundancy of data, the database has been improved to ensure the accuracy and integrity of the data.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.67-80
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• 2011

This paper presents the results of shaking table tests on a 1:5 scale 10-story R.C. wall-type residential building model. The following conclusions are drawn based on the test results. (1) The model responded linear elastically under the excitations simulating an earthquake with a return period of 50 years, and showed a nonlinear response under the excitations simulating the design earthquake of Korea. (2) The model showed a significant strength drop under the maximum considered earthquake, with a return period of 2400 years. (3) The major portion of the resistance to lateral inertia forces came from the walls used for the elevator and stair case. (4) Finally, the damage and failure modes appear to be due to the flexural behavior of walls and slabs. A significant deterioration of stiffness and an elongation of the fundamental periods were observed under increased earthquake excitations.

• Korean Journal of Plant Resources
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• v.30 no.5
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• pp.549-555
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• 2017

The production of ginseng cultivation is decreasing due to shortage of cultivated land and climate change, so additional methods are needed. Therefore, the physiological and morphological characteristics of finebubble were analyzed by applying them to ginseng cultivation which is the representative crop of Korea. The application of fine bubble water to 2 year old ginseng showed that stem length and leaf were increased, and weight increased as main root increased in root. In particular, it is shown that the weight of roots increases with the increase of leaf size. This is because the total chlorophyll content is high and it is judged to be related to the increase of photosynthesis efficiency. When the results of this study were confirmed, it was confirmed that ginseng cultivation using fine bubbles showed no inhibition of growth of ginseng. According to the results of physiological characteristics and subdividing results, It was confirmed that the growth of about 10% to 15% of the growth was increased and that the growth of ginseng was increased by applying the fine bubble when growing ginseng.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.138-141
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• 2004

The environmental tracers tritium/helium-3 (3H/3He) and chlorofluorocarbons (CFCs) were investigated in ground water from Jeju Island, Korea, a basaltic volcanic island. The apparent 3H/3He and CFC-12 ages were in relatively good agreement in samples with low concentrations of terrigenic He. Ground water mixing was evaluated by comparing 3H and CFC-12 concentrations with mixing models, which distinguished old water with negligible 3H and CFC-12, young water with piston flow, and binary mixtures of the two end members. The ground water CFC-12 age is much older in water from wells completed in confined zones of the hydro-volcanic Seoguipo formation in coastal areas than in water from the basaltic aquifer. Comparison of major element concentrations in ground water with the CFC-12 age shows that nitrate contamination processes contribute more solutes in young water than are derived from water-rock interactions in non-contaminated old water. Chemical evolution of ground water resulting from silicate weathering in basaltic rocks reaches the zeolite-smectite phase boundary. The calcite saturation state of ground water increased with the CFC-12 apparent (piston flow) age. In agricultural areas, the temporal trend of nitrate concentration in ground water was consistent with the known history of chemical fertilizer use on Jeju Island, but the response of nitrate concentration in ground water to nitrogen inputs follows an approximate 10-year delay. Based on mass balance calculations, it was estimated that about 40% of the nitrogen applied by fertilizers reached the water table and contaminated ground water resources when the fertilizer use was at the highest level.

• Journal of the Korea Computer Industry Society
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• v.3 no.7
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• pp.921-926
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• 2002

B+-Tree is the most popular indexing method in DBMS to manage large size data in more efficiency. However the existing B+-Tree has shortcomings in there is overhead on DISK/IO when the first time of constructing DB or of making Index, and it lessens the concurrency if there are frequent delete operations so that the index structure also should be changed frequently. To solve these problems almost DBMS is using batch construction method and lazy deletion method. But to apply B+-Tree, which is using batch construction method and lazy deletion method, into DBMS the technique for controlling and recovering concurrency is necessary, but its researching is still unsatisfactory so that there is a problem on applying it into actual systems. On this paper I suggest the technique for controlling and recovering concurrency how to implement the batch construction method and the lazy deletion method in actual DBMS. Through the suggested technique there is no cascade rollback by using Pending list, it enhances the concurrency by enabling insertion and deletion for base table on every reconstruction, and it shortens transaction response time for user by using system queue which makes the batch constructing operation is processed not in user's transaction level but in system transaction level.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.11_12
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• pp.717-721
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• 2005

With HTTP/1.0, a single request means a single HTTP connection so that the granular unit of dispatching is the same as real load. But with persistent HTTP connection, multiple requests may arrive on a single TCP connection. Therefore, a scheme that dispatches load at the granularity of individual requests constrains the feasible dispatching policies In this paper we propose a new connection dispatching polity for supporting HTTP/1.1 persistent connections in cluster-based Web servers. When the request of a base html file arrives, the dispatcher gets the subsequent load arriving on that connection using the embedded objects information. After the dispatcher stores the load information in Load Table, the dispatcher employs the connection aging strategy on live persistent connections on the passage of time. The results of simulation show about $1.7\%\~16.8\%$ improved average response time compared to existing WLC algorithm.