• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.1-7
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• 2021

In order to acquire an image in a positron emission tomography, it is necessary to draw the position coordinates of the scintillation pixels of the detector module measured at the same time. To this end, in a detector module using a plurality of scintillation pixels and a small number of photosensors, it is necessary to obtain a flood image and divide a region of each scintillation pixel to obtain a position of a scintillation pixel interacting with a gamma ray. Alternatively, when the number of scintillation pixels and the number of photosensors to be used are the same, the position coordinates for the position of the scintillation pixels can be directly acquired as digital signal coordinates. A method of using a plurality of scintillation pixels and a small number of photosensors requires a process of obtaining digital signal coordinates requires a plurality of photosensors and a signal processing system. This complicates the signal processing process and raises the cost. To solve this problem, in this study, we developed a method of obtaining digital signal coordinates without performing the process of separating the planar image and region using a plurality of flash pixels and a small number of optical sensors. This is a method of obtaining the position coordinate values of the flash pixels interacting with the gamma ray as a digital signal through a look-up table created through the signals acquired from each flash pixel using the maximum likelihood function. Simulation was performed using DETECT2000, and verification was performed on the proposed method. As a result, accurate digital signal coordinates could be obtained from all the flash pixels, and if this is applied to the existing system, it is considered that faster image acquisition is possible by simplifying the signal processing process.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.6A
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• pp.163-177
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• 2008

As many companies are considering to use server virtualization technology to reduce cost, the crime rates in virtual server environment are expected to be increasing rapidly. The server virtualization solution has a basic function to produce virtual machine images without using any other disk imaging tools, so that investigating virtual servers are more efficient because the investigator only has to collect the virtual machine image and submit it to the court. However, the virtual machine image has no admissibility to be the legal evidence because of security, authenticity, procedural problems in collecting virtual machine images on virtual servers. In this research, we are going to provide requirements to satisfy security, authenticity and chain of custody conditions for the admissibility of the virtual machine image in server virtualization environment. Additionally, we suggest definite roles and driving plans for related organizations to produce virtual machine image as a admissible evidence.

• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.41-50
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• 2020

Since cracks in concrete structures expedite corrosion of reinforced concrete over a long period of time, regular on-site inspections are essential to ensure structural usability and prevent degradation. Most of the safety inspections of facilities rely on visual inspection with naked eye, so cost and time consuming are severe, and the reliability of results differs depending on the inspector. In this study, a portable measuring device that can be used for safety diagnosis and maintenance was developed as a device that measures the width and length of concrete cracks through image analysis of cracks photographed with a camera. This device captures the cracks found within a close distance (3 m), and accurately calculates the unit pixel size by laser distance measurement, and automatically calculates the crack length and width with the image processing algorithm developed in this study. In measurement results using the crack image applied to the experiment, the measurement of the length of a 0.3 mm crack within a distance of 3 m was possible with a range of about 10% error. The crack width showed a tendency to be overestimated by detecting surrounding pixels due to vibration and blurring effect during the binarization process, but it could be effectively corrected by applying the crack width reduction function.

• International Journal of Advanced Culture Technology
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• v.9 no.1
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• pp.16-21
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• 2021

As the average age of national veterans has increased from 69 years old(2011) to 71 years old(since 2015) over the past five years, the overall medical service cost of veterans has increased by about 20%. The main cause of this phenomenon is 'ultra-aging', which accounts for 67% of veterans, while the proportion of health insurance patients aged 70 or older is 9%. Therefore, it is judged that the analysis of the trend of use of medical services at veterans hospitals in each region that is in charge of severe medical services of national veterans can serve as an opportunity to seek countermeasures for the severe medical system of national veterans. First of all, based on the details of major medical expenses (hospitalization, outpatient, pharmaceutical expenses) by region for the last 10 years(2010-2019), data significance was performed through a chi-square test, and the Central Veterans Hospital and Non-Central Veterans Hospital using EXCEL. 'Expected frequency' was calculated by year. By applying the CHITEST(observation frequency, expected frequency) function again, the p-value(p<0.05) was calculated, and the profit bias of each region's veterans hospital could be determined. The specific research method is for the last 10 years(2010-2019) for state-sponsored patients_outpatient treatment income, state-sponsored patients_hospitalization income, exempt patients_outpatients at the Central Veterans Hospital, Busan Veterans Hospital, Gwangju Veterans Hospital, Daegu Veterans Hospital, and Daejeon Veterans Hospital. A one-way analysis of variance was conducted to verify the significance of the difference between group averages on the status of 5 medical revenues of veterans hospitals in each of the 5 regions, including medical treatment income, reduced patients_hospitalization income, and reduced patients_medicine expenses. It was found to be significant(p<0.05) at all levels, including region and type. Finally, the bias in the profit structure of regional veterans hospitals was the highest in 2017(p=0.0004) and the lowest in 2013(p=0.0349). In addition, in the profit structure of the Veterans Hospital, the year in which the'regional' variable worked the most was 2019, and the year with the least affected was 2010. The order of the former is Jungang(=31,674,713), Busan(=12,314,614), Gwangju(=11,957,038), Daegu(=10,168,015), and Daejeon(=6,991,034), and the order of the latter is Jungang(=57,868,791), and Busan(=19,183,194). Gwangju(=17,904,712), Daegu(=15,656,034), and Daejeon(=14,377,395). In conclusion, the profit bias of veterans hospitals repeatedly raced the lowest(p=0.01986) and highest(p=0.03499) for the past five years(2010-2014) year by year, with the 'regional' variable being the most in the veterans hospital's profit structure It was identified as a major influence factor. On the other hand, for the last 5 years (2015-2019), the influence factors of the'regional' variable every year were in 2015(p=0.02015), 2016(p=0.01741), 2017(p=0.00045), and 2018(p=0.00394). in 2019(p=0.00227), a significant difference was confirmed at a very low level.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.55-62
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• 2022

The perovskite solar cell is an active part of research in renewable energy fields such as solar energy, wind, hydroelectric power, marine energy, bioenergy, and hydrogen energy to replace fossil fuels such as oil, coal, and natural gas, which will gradually disappear as power demand increases due to the increase in use of the Internet of Things and Virtual environments due to the 4th industrial revolution. The perovskite solar cell is a solar cell device using an organic-inorganic hybrid material having a perovskite structure, and has advantages of replacing existing silicon solar cells with high efficiency, low cost solutions, and low temperature processes. In order to optimize the light absorption layer thin film predicted by the existing empirical method, reliability must be verified through device characteristics evaluation. However, since it costs a lot to evaluate the characteristics of the light-absorbing layer thin film device, the number of tests is limited. In order to solve this problem, the development and applicability of a clear and valid model using machine learning or artificial intelligence model as an auxiliary means for optimizing the light absorption layer thin film are considered infinite. In this study, to estimate the light absorption layer thin-film optimization of perovskite solar cells, the regression models of the support vector machine's linear kernel, R.B.F kernel, polynomial kernel, and sigmoid kernel were compared to verify the accuracy difference for each kernel function.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.412-419
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• 2022

For treatment of partially edentulous patients, a treatment using implant is widely used. Treatment method using implant are implant fixed prostheses and removable partial dentures, and for patients with severe bone resorption, removable implant overdenture with the effects of aesthetic and reducing cost can be used as treatment options. Specially, prosthesis with milled-bar and attachment has the effect of being splinted between implant fixtures, higher retention and stability than conventional removable partial denture. And it has the effect of improvement of aesthetic through lip support by denture base. In this case, the patient with severe alveolar bone resorption and partial edentulous maxilla and mandible was treated by implant-assisted removable partial denture using Milled-bar and ADD-TOC attachment. The esthetic was improved by removing the clasp because of effects of additional retention by using the attachment, and reducing palatal coverage of implant-assisted removable partial denture. The clinical results were satisfactory on the aspect of aesthetic and masticatory function.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.655-660
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• 2022

This paper analyzes the problem of the economic order quantity (lot size) of a retailer in a two-stage supply chain consisting of a supplier, a retailer(distributor), and a customer. In this two-stage supply chain, the supplier permits the retailer to defer payment for a certain fixed period of time for the purchase cost to be paid by the retailer as a price differentiation strategy with his competitor. In addition, in the case of customer goods such as food and grain, it is common to see that end-customer demand is generally depend on the level of inventory displayed by the retailer. From this perspective, this paper analyzes the inventory problem of retailers under the assumption that the supplier may allow a certain period to suspend payments for the purchase of goods and the end customer demand is a function of the retailer's inventory level increasing with size. In this regard, we need to analyze how much the length of the grace period for product purchase costs affect the retailer's lot-sizing policy. Therefore, we formulate the retailer's annual net profit and analyze the effect of the length of credit period on the retailer's inventory policy numerically.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.1
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• pp.8-17
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• 2023

In conventional liquid crystal display(LCD) manufacturing process, Indium Tin Oxide(ITO) as transparent electrode and rubbing process of polyimide as alignment layer are essential process to apply electric field and align liquid crystal molecules. However, there are some limits that deposition of ITO requires high vacuum state, and rubbing process might damage the device with tribolectric discharge. In this paper, we made nanocomposite with PEDOT:PSS and MWNT to replace ITO and constructed alignment layer by nano imprint lithography with nano wrinkle pattern, to replace rubbing process. These replacement made that only one PEDOT:PSS/MWNT film can function as two layers of ITO and polyimide alignment layer, which means simplification of process. Transferred nano wrinkle patterns functioned well as alignment layer, and we found out lowered threshold voltage and shortened response time as MWNT content increase, which is related to increment of electric conductivity of the film. Through this study, it may able to contribute to process simplification, reducing process cost, and suggesting a solution to disadvantage of rubbing process.

• Korean Journal of Acupuncture
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• v.40 no.1
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• pp.1-12
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• 2023

Objectives : This study aims to provide information regarding the status and quality of mobile applications (MAs) using self-acupressure by performing a systematic review. Methods : We conducted comprehensive searching on five international databases and two app markets from inception to July 31, 2022 to identify MAs using self-acupressure. We analyzed the characteristics of each MA regarding the name of the MA, registered app markets, target symptoms, developers, the year and country of development, cost, target age, media function, and expertise. We assessed the quality of each MA using Mobile Application Rating Scale (MARS). Results : We identified a total of 30 MAs using self-acupressure (25 MAs from the app market and 6 MAs from clinical studies, with 1 MA in common). 17 out of 24 MAs from the app market provided self-acupressure regimens for various symptoms and the others provided regimens for specific symptoms such as memory, anxiety, depression, asthma, allergy, low back pain, and headache. 14 developers were reported. 23 MAs were developed after 2013. The largest number of MAs were developed in the United States. The target age group of 12 MAs was above the age of 3, and that of 11 MAs was above the age of 12. 14 MAs provided multimedia functions such as videos. 13 MAs provided information of expertise. From clinical studies, only 3 out of 6 MAs were accessible through the app market. 4 MAs were developed by the researchers of the study. In terms of MARS, the score of MAs from the app market was higher than that of MAs from clinical studies in both objective and subjective evaluation areas. Conclusions : This study summarizes the characteristics of MAs using self-acupressure. More MAs using self-acupressure should be developed and further clinical research for MA on each symptom and disease is warranted for the diversification of MA fields using self-acupressure.

• Journal of Service Research and Studies
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• v.13 no.3
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• pp.105-126
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• 2023

The domestic used car market continues to grow along with the used car online platform service. The used car online platform service discloses vehicle specifications, accident history, inspection history, and detailed options to service consumers. Most of the preceding studies were predictions of used car prices using vehicle specifications and some options for vehicles. As a result of the study, it was confirmed that there was a nonlinear relationship between used car prices and some specification variables. Accordingly, the researchers tried to solve the nonlinear problem by executing a Machine Learning model. In common, the Regression based Machine Learning model had the advantage of knowing the actual influence and direction of variables, but there was a disadvantage of low Cost Function figures compared to the Decision Tree based Machine Learning model. This study attempted to predict used car prices of six domestic brands by utilizing both vehicle specifications and vehicle options. Through this, we tried to collect the advantages of the two types of Machine Learning models. To this end, we sequentially conducted a regression based Machine Learning model and a decision tree based Machine Learning model. As a result of the analysis, the practical influence and direction of each brand variable, and the best tree based Machine Learning model were selected. The implications of this study are as follows. It will help buyers and sellers who use used car online platform services to predict approximate used car prices. And it is hoped that it will help solve the problem caused by information inequality among users of the used car online platform service.