• Land and Housing Review
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• v.14 no.4
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• pp.17-37
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• 2023

The rental housing market in South Korea, specifically monthly rent with deposit, has been expanding over the last three decades (8.2% in 1990 to 21.0% in 2020), partly replacing the traditional Jeonse market. The distribution of rent has changed due to public rental subsidies and the emergence of luxury rental housing, while the distribution of rental household income has been polarized because of the emergence of rich renters. This study attempts to measure the structural changes in the rental market by developing a new indicator of income-rent mismatch. Using the seven series of the Korea Housing Survey, this study analyzed the changes in rent (reflecting the conversion rate) and income levels of rental households in 2006 (base year) and 10-15 years later (the analysis year) at the national level and at the spatial unit of 16 metropolitan cities and provinces (excluding Sejong), respectively, by dividing them into quartile data. The result reveals that rental housing was undersupplied in middle- and high-income rental housing due to the decline in the highest quartile (25%→18%) and the third quartile groups (25%→20%), while the supply of public rental housing expanded for the second quartile (25%→28%) and the lowest quartile (25%→35) groups. On the demand side, the highest income quartile shrank (25%→21%), while the lowest income quartile grew (25%→31%). Comparing the 16 metropolitan cities and provinces, there were significant regional differences in the direction and intensity of changes in rent and renter household income. In particular, the rental market in Seoul was characterized by supply polarization, which led to an imbalance in the income distribution of rental households. The structural changes in the apartment rental market were different from those in the non-apartment rental market. The findings of this study can be used as a basis for future regional rental housing markets. The findings can support securing affordable rental housing stock for each income quartile group on monthly rent and developing housing stability measures for a balance between income and rent distribution in each region.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.5
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• pp.67-80
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• 2022

This study was conducted to derive policy measures such as fostering and supporting by examining the actual conditions of domestic startups. The subject of this study was the start-ups located in Seongnam-si, where Pangyo Techno Valley, which is the highest-level innovation cluster in Korea and is evaluated as a start-up mecca. Startups were defined as startups under 7 years old based on new technologies such as IT, BT, and CT, and the subjects of the study were selected. This can be seen as a step forward from previous research in that it embodies the concept of a startup that was previously abstract in a quantitatively measurable way. As a result of the analysis, about 94% of startups are distributed in the so-called "Death Valley" growth stage, and startups above scale-up, which means full-scale growth beyond BEP, account for about 6%. appeared to be occupied. He cited the problem of start-up funds as the biggest difficulty in the early stages of startups, and cited the loan evaluation method that prioritizes sales or collateral in raising funds as the biggest problem. In addition, start-ups rated the access to private investment capital such as VC, AC, and angel investors at a low level compared to policy funds, which are public funds. Most startups showed a lot of interest in overseas expansion, and they chose matching overseas investors such as overseas VCs as the biggest support for overseas expansion. The overall competitiveness in the overseas market was 49.6 points, which is less than 50 points out of 100, indicating that the overall competitiveness was somewhat inferior. It was analyzed that public support and investment in overseas sales channels (sales channels, distribution networks, etc.) should be prioritized along with enhancement of technological competitiveness in order for domestic startups to increase their competitiveness in overseas markets as well as in the domestic market.

• Journal of Marine Life Science
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• v.9 no.1
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• pp.9-21
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• 2024

Paralytic shellfish poisoning (PSP) including Saxitoxin (STX) is caused by harmful algae, and poisoning occurs when the contaminated seafood is consumed. The mouse bioassay (MBA), a standard test method for detecting PSP, is being sanctioned in many countries due to its low detection limit and the animal concerns. An alternative to the MBA is the Neuro-2a cell-based assay. This study aimed to establish various test conditions for Neuro-2a assay, including cell density, culture conditions, and STX treatment conditions, to suit the domestic laboratory environment. As a result, the initial cell density was set to 40,000 cells/well and the incubation time to 24 hours. Additionally, the concentration of Ouabain and Veratridine (O/V) was set to 500/50 μM, at which most cells died. In this study, we identified eight concentrations of STX, ranging from 368 to 47,056 fg/μl, which produced an S-shaped dose-response curve when treated with O/V. Through inter-laboratory variability comparison of the Neuro-2a assay, we established five Quality Control Criteria to verify the appropriateness of the experiments and six Data Criteria (Top and Bottom OD, EC₅₀, EC₂₀, Hill slop, and R² of graph) to determine the reliability of the experimental data. The Neuro-2a assay conducted under the established conditions showed an EC₅₀ value of approximately 1,800~3,500 fg/μl. The intra- & inter-lab variability comparison results showed that the coefficients of variation (CVs) for the Quality Control and Data values ranged from 1.98% to 29.15%, confirming the reproducibility of the experiments. This study presented Quality Control Criteria and Data Criteria to assess the appropriateness of the experiments and confirmed the excellent repeatability and reproducibility of the Neuro-2a assay. To apply the Neuro-2a assay as an alternative method for detecting PSP in domestic seafood, it is essential to establish a toxin extraction method from seafood and toxin quantification methods, and perform correlation analysis with MBA and instrumental analysis methods.

• Journal of the Korean Society of Radiology
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• v.82 no.3
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• pp.670-681
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• 2021

Purpose This study aimed to investigate the optimal threshold value in Hounsfield units (HU) on CT to detect the solid components of pulmonary subsolid nodules using pathologic invasive foci as reference. Materials and Methods Thin-section non-enhanced chest CT scans of 25 patients with pathologically confirmed minimally invasive adenocarcinoma were retrospectively reviewed. On CT images, the solid portion was defined as the area with higher attenuation than various HU thresholds ranging from -600 to -100 HU in 50-HU intervals. The solid portion was measured as the largest diameter on axial images and as the maximum diameter on multiplanar reconstruction images. A linear mixed model was used to evaluate bias in each threshold by using the pathological size of invasive foci as reference. Results At a threshold of -400 HU, the biases were lowest between the largest/maximum diameter of the solid portion of subsolid nodule and the size of invasive foci of the pathological specimen, with 0.388 and -0.0176, respectively. They showed insignificant difference (p = 0.2682, p = 0.963, respectively) at a threshold of -400 HU. Conclusion For quantitative analysis, -400 HU may be the optimal threshold to define the solid portion of subsolid nodules as a surrogate marker of invasive foci.

• Journal of Korean Society of Disaster and Security
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• v.17 no.1
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• pp.9-16
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• 2024

In Korea, as disasters become larger and more complex, there is a trend of shifting from a focus on response and recovery to a focus on prevention and preparedness. In order to prevent and prepare for disasters, each local government manages disaster management resources by stockpiling them. However, although disaster management resources are stored in individual warehouses, they are managed by department rather than by warehouse, resulting in insufficient management of disaster management resources due to the heavy workload of those in charge. In order to intensively manage these disaster management resources, an integrated disaster management resource management center is established and managed at the metropolitan/provincial level. In the case of Gangwon-do, the subject of this study, a warehouse is rented and operated as an integrated disaster management resource management center. When leasing an integrated management center, there is the inconvenience of having to move the location every 1 to 2 years, so it is deemed necessary to build a dedicated facility in an available site. To select a location candidate, network analysis was used to measure access to and use of facilities along interconnected routes of networks such as roads and railways. During network analysis, the Location-Allocation method, which was widely used in the past to determine the location of multiple facilities, was applied. As a result, Hoengseong-gun in Gangwon-do was identified as a suitable candidate site. In addition, if the integrated management center uses our country's logistics system to stockpile disaster management resources, local governments can mobilize disaster management resources in 3 days, and it is said that it takes 3 days to return to normal life after a disaster occurs. Each city's disaster management resource stockpile is 3 days' worth per week, and the integrated management center stores 3 times the maximum of the city's 4-day stockpile.

• Food Science and Preservation
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• v.31 no.2
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• pp.267-275
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• 2024

Artemisia fukudo Makino belongs to the Asteraceae family, is a halophyte that can grow in salinity soils and is known for its various physiological activities. However, few studies were comparing it according to the growth environment. Therefore, in this study, we analyzed the antioxidant activity, functional ingredients, and safety of Artemisia fukudo Makino according to the growth environment. Total polyphenol content was the highest in native mature leaves, but 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity was higher in cultivated leaves than in native leaves. The total mineral content, excluding sodium, was higher in cultivated than in native leaves. The content of potassium and calcium was higher in cultivated leaves than in native leaves. In addition, heavy metal analysis showed that cultivated leaves were generally lower than those of native leaves. Residual pesticides were not detected in all samples. In conclusion, since there is no significant difference in cultivated leaves compared to native leaves, it was judged that cultivated leaves could be used as a variety to be grown and mass-produced.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.134-144
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• 2009

Paleoproductivity changes in the central part of the Bering Sea since the last glacial period were reconstructed by analyzing opal and total organic carbon (TOC) content and their mass accumulation rate (MAR) in sediment core PC23A. Ages of the sediment were determined by both AMS $^{14}C$ dates using planktonic foraminifera and Last Appearance Datum of radiolaria (L. nipponica sakaii). The core-bottom age was calculated to reach back to 61,000 yr BP. and some of core-top was missing. Opal and TOC contents during the last glacial period varied in a range of 1-10% and 0.2-1.0%, and their average values are 5% and 0.7%, respectively. In contrast, during the last deglaciation, opal and TOC contents varied from 5 to 22% and from 0.8 to 1.2%, respectively, with increasing average values of 8% and 1.0%. Opal and TOC MAR were low ($1gcm^{-2}kyr^{-1}$, $0.2gcm^{-2}kyr^{-1}$) during the last glacial period, but they increased (>5 and >$1gcm^{-2}kyr^{-1}$) during the last deglaciation. High diatom productivity during the last deglaciation was most likely attributed to the elevated nutrient supply to the sea surface resulting from increased melt water input from the nearby land and enhanced Alaskan Stream injection from the south under the restricted sea-ice and warm condition during the rising sea level. On the contrary, low productivity during the last glacial period was mainly due to decreased Alaskan Stream injection during the low sea-level condition as well as to extensive development of sea ice under low-temperature seawater and cold environment.

• Journal of agricultural medicine and community health
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• v.25 no.2
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• pp.397-411
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• 2000

The present study was conducted to analyze the degree of changes in knowledge and attitude toward health, arid health promoting activities after providing health education intervention for a year to elementary school children, to examine the factors effecting knowledge, attitude and health promoting practices for obesity and diet, and to analyze whether changes are present in health level according to changes in knowledge on health and health promoting activities. After conducting a pre-survey rio 354 subjects of 3rd and 4th grade students and their mothers in the city area of Kyungju, in April, 1999, 301. responses with the responding rate of 85% were obtained. Final analysis was done with 231 pairs of a student and his/her mother who could be followed up after a year among 301 pairs of the respondents, excluding those students who transferred, those who were excused from school early, those who did not take abdominal fat measurements, and those students and mothers respondents whose survey was incomplete. Based on the changes before and after the intervention, the scores on knowledge about obesity and diet showed a significant difference in normal weight group, and the scores on the attitude toward obesity and diet increased significantly in obesity group but decreased significantly in normal weight group(p<0.01). The scores of practicing health promoting activities were significantly increased in both groups, and although the waist-hip ratio (WHR) did not change in obesity group, the rate increased significantly in normal weight group(p<0.01). As for changes on the knowledge of obesity and diet before and after the intervention while dividing the scores into 3 levels based on the scores of the pre-survey and compared to changes in the scores one year after, in the case of the changes in the scores in the 1st third, the score on the knowledge about obesity and diet changed from 1.3 in the pre survey to 3.7 after the intervention, showing significant increase(p<0.01) The scores of practicing health promoting activities for obesity and diet were significantly increase in all three levels(p<0.01), and the degree of changes in the scores was 7.0 points in the 1st third, 4.4 points for the and third and 1.8 points for the 3rd third, showing a significant difference among the three levels(p<0.01). It was shown that the increase in BMI in those students whose mothers have the education level higher than university was significantly higher than the increase in BMI in those students whose mothers have the education level under high school, and those students whose mothers are in their 30's showed higher changes in practicing health promoting activities for obesity and diet. When the scores of mothers' knowledge and attitude toward obesity and diet were compared by dividing the scores into tertile, the score of students' knowledge changed significantly according to the scores of mothers' attitude toward obesity and diet. In multiple regression analysis on changes in the scores of knowledge about obesity and diet, the student variables of the degree of awareness on the seriousness of obesity, and the scores of previous knowledge on diet and obesity were selected the significant variables, and among the mother variables, the degree of guiding the child on diet and the education level were the significant variables. In multiple regression analysis to analyze the factors effecting changes in the attitude toward obesity and diet, the student variables of the BMI, scores of previous knowledge on obesity and diet, and scores on the previous attitude toward obesity and diet were shown to be significant. In multiple regression analysis on the factors effecting changes in health promoting activities for obesity and diet, the student variables of the BMI, scores on the previous attitude toward obesity and diet, and changes in the scores of obesity and diet were selected the significant variables.

• Journal of Intelligence and Information Systems
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• v.23 no.4
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• pp.77-110
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• 2017

Recently, the diversification and individualization of consumption patterns through the web and mobile devices based on the Internet have been rapid. As this happens, the efficient operation of the offline store, which is a traditional distribution channel, has become more important. In order to raise both the sales and profits of stores, stores need to supply and sell the most attractive products to consumers in a timely manner. However, there is a lack of research on which SKUs, out of many products, can increase sales probability and reduce inventory costs. In particular, if a company sells products through multiple in-store stores across multiple locations, it would be helpful to increase sales and profitability of stores if SKUs appealing to customers are recommended. In this study, the recommender system (recommender system such as collaborative filtering and hybrid filtering), which has been used for personalization recommendation, is suggested by SKU recommendation method of a store unit of a distribution company that handles a homogeneous brand through a plurality of sales stores by country and region. We calculated the similarity of each store by using the purchase data of each store's handling items, filtering the collaboration according to the sales history of each store by each SKU, and finally recommending the individual SKU to the store. In addition, the store is classified into four clusters through PCA (Principal Component Analysis) and cluster analysis (Clustering) using the store profile data. The recommendation system is implemented by the hybrid filtering method that applies the collaborative filtering in each cluster and measured the performance of both methods based on actual sales data. Most of the existing recommendation systems have been studied by recommending items such as movies and music to the users. In practice, industrial applications have also become popular. In the meantime, there has been little research on recommending SKUs for each store by applying these recommendation systems, which have been mainly dealt with in the field of personalization services, to the store units of distributors handling similar brands. If the recommendation method of the existing recommendation methodology was 'the individual field', this study expanded the scope of the store beyond the individual domain through a plurality of sales stores by country and region and dealt with the store unit of the distribution company handling the same brand SKU while suggesting a recommendation method. In addition, if the existing recommendation system is limited to online, it is recommended to apply the data mining technique to develop an algorithm suitable for expanding to the store area rather than expanding the utilization range offline and analyzing based on the existing individual. The significance of the results of this study is that the personalization recommendation algorithm is applied to a plurality of sales outlets handling the same brand. A meaningful result is derived and a concrete methodology that can be constructed and used as a system for actual companies is proposed. It is also meaningful that this is the first attempt to expand the research area of the academic field related to the existing recommendation system, which was focused on the personalization domain, to a sales store of a company handling the same brand. From 05 to 03 in 2014, the number of stores' sales volume of the top 100 SKUs are limited to 52 SKUs by collaborative filtering and the hybrid filtering method SKU recommended. We compared the performance of the two recommendation methods by totaling the sales results. The reason for comparing the two recommendation methods is that the recommendation method of this study is defined as the reference model in which offline collaborative filtering is applied to demonstrate higher performance than the existing recommendation method. The results of this model are compared with the Hybrid filtering method, which is a model that reflects the characteristics of the offline store view. The proposed method showed a higher performance than the existing recommendation method. The proposed method was proved by using actual sales data of large Korean apparel companies. In this study, we propose a method to extend the recommendation system of the individual level to the group level and to efficiently approach it. In addition to the theoretical framework, which is of great value.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.157-166
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• 2000

Purpose : This investigation was peformed in order to improve the health care of radiation workers, to predict a risk, to minimize the radiation exposure hazard to them and for them to realize radiation exposure danger when they work in radiation area in hospital. Methods and Materials : The documentations checked regularly for personal radiation exposure in four university hospitals in Pusan city in Korea between January 1, 1993 and December 31, 1997 were analyzed. There were 458 persons in this documented but 111 persons who worked less then one year were excluded and only 347 persons were included in this study. Results : The average of yearly radiation exposure of 347 persons was 1.52$\pm$1.35 mSv. Though it was less than 50mSv, the limitaion of radiation in law but 125 (36%) people received higher radiation exposure than non-radiation workers. Radiation workers under 30 year old have received radiation exposure of mean 1.87$\pm$1.01 mSv/year, mean 1.22$\pm$0.69 mSv between 31 and 40 year old and mean 0.97$\pm$0.43 mSv/year over 41year old (p<0.001). Men received mean 1.67$\pm$1.54 mSv/year were higher than women who received mean 1.13$\pm$0.61 mSv/year (p<0.01). Radiation exposure in the department of nuclear modicine department in spite of low energy sources is higher than other departments that use radiations in hospital (p<0.05). And the workers who received mean 3.59$\pm$1.81 msv/year in parts of management of radiation sources and injection of sources to patient receive high radiation exposure in nuclear medicine department (p<0.01). In department of diagnostic radiology high radiation exposure is in barium enema rooms where workers received mean 3.74$\pm$1.74 mSv/year and other parts where they all use fluoroscopy such as angiography room of mean 1.17$\pm$0.35 mSv/year and upper gastrointestinal room of mean 1.74$\pm$1.34 mSv/year represented higher radiation exposure than average radiation exposure in diagnostic radiology (p<0.01). Doctors and radiation technologists received higher radiation exposure of each mean 1.75$\pm$1.17 mSv/year and mean 1.50$\pm$1.39 mSv/year than other people who work in radiation area in hospital (p<0.05). Especially young doctors and technologists have the high opportunity to receive higher radiation exposure. Conclusions : The training and education of radiation workers for radiation exposure risks are important and it is necessary to rotate worker in short period in high risk area. The hospital management has to concern health of radiation workers more and to put an effort to reduce radiation exposure as low as possible in radiation areas in hospital.