• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.1
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• pp.37-48
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• 2021

A new high speed rotation type-passive sampling device (HSR-PSD), which can rotate seawater at high speed and absorb easily and quickly the freely dissolved hydrophobic organic contaminants from seawater, was developed and then applied around the Korean Peninsula. Freely dissolved concentrations (Cfree) of polycyclic aromatic hydrocarbons (PAHs) were determined using the HSR-PSD with low density polyethylene (LDPE) sheets as a passive sampler. Furthermore, dissolved concentrations (Cdissolved) of PAHs in seawater were also obtained from high volume water sampling as a conventional method to account for actual bioavailability. When the LDPE sheets were rotated in the HSR-PSD at 900 rpm, PAHs with log KOW 3.4 ~ 5.2 were equilibrated between the LDPE and water in 5 hours. Although the high molecular weight PAHs with log KOW 5.6 ~ 6.8 was expected to be 2 to 30 days to reach the equilibrium, the Cfree of the PAHs at equilibrium could be corrected using performance reference compounds in 5 hours. Meanwhile, the total Cfree of PAHs were from 0.32 to 1.2 ng/L, which were higher than reported values in other oceans, but lower than in coastal water such as estuary, harbor, or shore. A bioavailability from the detected PAHs was highest at the sampling line near the dumping site of the Yellow Sea. Predicted residual concentrations in biota were relatively higher in offshore including the dumping site than in coastal regions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.298-307
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• 2021

Typhoons occur intensively between July and October, and the sea level is the highest during this time. In particular, the mean sea level in summer in Korea is higher than the annual mean sea level about 14.5cm in the west coast, 9.0 to 14.5cm in the south coast, and about 9.0 cm in the east coast. When the rising the sea level and a large typhoon overlap in summer, it can cause surges and flooding in low-lying coastal areas. Therefore, accurate calculation of the surge height is essential when designing coastal structures and assessing stability in order to reduce coastal hazards on the lowlands. In this study, the typhoon surge heights considering the summer mean sea level rise (SH_m) was calculated, and the validity of the analysis of abnormal phenomena was reviewed by comparing it with the existing surge height considering the annual mean sea level (SH_a). As a result of the re-analyzed study of typhoon surge heights for BOLAVEN (SANBA), which influenced in August and September during the summer sea level rise periods, yielded the differences of surge heights (cm) between SH_a and SH_m 7.8~24.5 (23.6~34.5) for the directly affected zone of south-west (south-east) coasts, while for the indirect southeast (south-west) coasts showed -1.0~0.0 (8.3~12.2), respectively. Whilst the differences between SH_a and SH_m of typhoons CHABA (KONG-REY) occurred in October showed remarkably lessened values as 5.2~ 14.2 (19.8~21.6) for the directly affected south-east coasts and 3.2~6.3 (-3.2~3.7) for the indirectly influenced west coast, respectively. The results show the SH_a does not take into account the increased summer mean sea level, so it is evaluated that it is overestimated compared to the surge height that occurs during an actual typhoon. Therefore, it is judged that it is necessary to re-discuss the feasibility of the surge height standard design based on the existing annual mean sea level, along with the accurate establishment of the concept of surge height.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.401-408
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• 2022

As research on a controlled environment system based on crop growth environment sensing for sustainable production of horticultural crops and its industrial use has been important, research on how to properly utilize soil moisture sensors for outdoor cultivation is being actively conducted. This experiment was conducted to suggest the proper method of utilizing the TEROS 12, an FDR (frequency domain reflectometry) sensor, which is frequently used in industry and research fields, for each orchard soil in three regions in Korea. We collected soils from each orchard where fruit trees were grown, investigated the soil characteristics and soil water retention curve, and compared TEROS 12 sensor calibration equations to correlate the sensor output to the corresponding soil volumetric water content through linear and cubic regressions for each soil sample. The estimated value from the calibration equation provided by the manufacturer was also compared. The soil collected from all three orchards showed different soil characteristics and volumetric water content values by each soil water retention level across the soil samples. In addition, the cubic calibration equation for TEROS 12 sensor showed the highest coefficient of determination higher than 0.95, and the lowest RMSE for all soil samples. When estimating volumetric water contents from TEROS 12 sensor output using the calibration equation provided by the manufacturer, their calculated volumetric water contents were lower than the actual volumetric water contents, with the difference up to 0.09-0.17 m³·m^-3 depending on the soil samples, indicating an appropriate calibration for each soil should be preceded before FDR sensor utilization. Also, there was a difference in the range of soil volumetric water content corresponding to the soil water retention levels across the soil samples, suggesting that the soil water retention information should be required to properly interpret the volumetric water content value of the soil. Moreover, soil with a high content of sand had a relatively narrow range of volumetric water contents for irrigation, thus reducing the accuracy of an FDR sensor measurement. In conclusion, analyzing soil water retention characteristics of the target soil and the soil-specific calibration would be necessary to properly quantify the soil water status and determine their adequate irrigation point using an FDR sensor.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.259-270
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• 1985

Meteorological year variations for rice crop from 1973 to 1984 were compared by using air temperature and sunshine hour for nursery period, cooling index for reproductive stage and meteorological yield productivity index for ripening period. The most optimum transplanting date and heading date for crop yield based on real transplanting date-grain yield relationship or heading date-grain yield relationship, meteorological yield productivity index and actual results showed good agreement each other. Around May 26 for transplanting and August 10 for heading were the most optimum date in Indica/Japonica hybrid cultivars while these were about June 8 and August 23 for Japonica cultivars, respectively. On the other hand, theoretical late limiting heading date for safe ripening were August 20 for Indica/Japonica hybrid cultivars and August 30 for Japonica cultivars, respectively, for both methods, cumulative temperature method during ripening with 80% believable frequency and meteorological yield productive index method having 1000(kg/10a) yielding potential. Based on the yield forecast trial, the highest values of photosynthetic efficiency, 2.5%, and crop growth rate, 23g/㎡/day, were recorded during 30 days before rice heading. Considering the photosynthetic efficiency and solar radiation, the potential crop growth rate was more or less 30g/㎡/day and the biological grain yielding potential in a existing cultural practices was approximately 900-1000(kg/10a) in Milyang weather condition. To increase further yielding potential, either photosynthetic efficiency or harvest index or both should be improved by manipulating appropriate canopy architecture, plant spacing, fertilizer, chemical, etc.

• Journal of the Korean Society for information Management
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• v.39 no.1
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• pp.257-280
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• 2022

In this study, we analyzed comments on news articles of representative companies of the three industries (i.e., semiconductor, secondary battery, and bio industries) that had been listed as national strategic technology projects of South Korea to identify public opinions towards them. In addition, we analyzed the relationship between changes in public opinion and stock price. 'Samsung Electronics' and 'SK Hynix' in the semiconductor industry, 'Samsung SDI' and 'LG Chem' in the secondary battery industry, and 'Samsung Biologics' and 'Celltrion' in the bio-industry were selected as the representative companies and 47,452 comments of news articles about the companies that had been published from January 1, 2020, to December 31, 2020, were collected from Naver News. The comments were grouped into positive, neutral, and negative emotions, and the dynamic topics of comments over time in each group were analyzed to identify the trends of public opinion in each industry. As a result, in the case of the semiconductor industry, investment, COVID-19 related issues, trust in large companies such as Samsung Electronics, and mention of the damage caused by changes in government policy were the topics. In the case of secondary battery industries, references to investment, battery, and corporate issues were the topics. In the case of bio-industries, references to investment, COVID-19 related issues, and corporate issues were the topics. Next, to understand whether the sentiment of the comments is related to the actual stock price, for each company, the changes in the stock price and the sentiment values of the comments were compared and analyzed using visual analytics. As a result, we found a clear relationship between the changes in the sentiment value of public opinion and the stock price through the similar patterns shown in the change graphs. This study analyzed comments on news articles that are highly related to stock price, identified changes in public opinion trends in the COVID-19 era, and provided objective feedback to government agencies' policymaking.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1353-1369
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• 2023

In the event of a disaster accident at sea, the scale of damage will vary due to weather effects such as wind, currents, and tidal waves, and it is obligatory to minimize the scale of damage by establishing appropriate control plans through quick on-site identification. In particular, it is difficult to identify pollutants that exist in a thin film at sea surface due to their relatively low viscosity and surface tension among pollutants discharged into the sea. Therefore, this study aims to develop an algorithm to detect suspended pollutants on the sea surface in RGB images using imaging equipment that can be easily used in the field, and to evaluate the performance of the algorithm using input data obtained from actual waters. The developed algorithm uses image enhancement techniques to improve the contrast between the intensity values of pollutants and general sea surfaces, and through histogram analysis, the background threshold is found,suspended solids other than pollutants are removed, and finally pollutants are classified. In this study, a real sea test using substitute materials was performed to evaluate the performance of the developed algorithm, and most of the suspended marine pollutants were detected, but the false detection area occurred in places with strong waves. However, the detection results are about three times better than the detection method using a single threshold in the existing algorithm. Through the results of this R&D, it is expected to be useful for on-site control response activities by detecting suspended marine pollutants that were difficult to identify with the naked eye at existing sites.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.4
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• pp.193-204
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• 2022

This study analyzed the degree of influence of measurement and improvement of customer satisfaction level targeting kiosk users. In modern times, due to the development of technology and the improvement of the online environment, the probability that simple labor tasks will disappear after 10 years is close to 90%. Even in domestic research, it is predicted that 'simple labor jobs' will disappear due to the influence of advanced technology with a probability of about 36%. there is. In particular, as the demand for non-face-to-face services increases due to the Corona 19 virus, which is recently spreading globally, the trend of introducing kiosks has accelerated, and the global market will grow to 83.5 billion won in 2021, showing an average annual growth rate of 8.9%. there is. However, due to the unmanned nature of these kiosks, some consumers still have difficulties in using them, and consumers who are not familiar with the use of these technologies have a negative attitude towards service co-producers due to rejection of non-face-to-face services and anxiety about service errors. Lack of understanding leads to role conflicts between sales clerks and consumers, or inequality is being created in terms of service provision and generations accustomed to using technology. In addition, since kiosk is a representative technology-based self-service industry, if the user feels uncomfortable or requires additional labor, the overall service value decreases and the growth of the kiosk industry itself can be suppressed. It is important. Therefore, interviews were conducted on the main points of direct use with actual users centered on display color scheme, text size, device design, device size, internal UI (interface), amount of information, recognition sensor (barcode, NFC, etc.), Display brightness, self-event, and reaction speed items were extracted. Afterwards, using the questionnaire, the Kano model quality attribute classification of each expected evaluation item was carried out, and Timko's customer satisfaction coefficient, which can be calculated with accurate numerical values The PCSI Index analysis was additionally performed to determine the improvement priorities by finally classifying the improvement impact of the kiosk expected evaluation items through research. As a result, the impact of improvement appears in the order of internal UI (interface), text size, recognition sensor (barcode, NFC, etc.), reaction speed, self-event, display brightness, amount of information, device size, device design, and display color scheme. Through this, we intend to contribute to a comprehensive comparison of kiosk-based research in each field and to set the direction for improvement in the venture industry.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.423-446
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• 2023

Shield TBM tunnel linings are segmented into segments and rings. This study investigates the response characteristics of the stress and displacement of the segment lining under seismic waves through modeling that considers the interface behavior between segments by applying a shell interface element to the contact surface between segments and rings. And there is no management criteria for ovaling deformation of segment linings in Korea. So, this study the ovality criteria and meaning of segment lining. The results of study showed that the distribution patterns of stress and displacement under seismic waves were similar between continuous linings and segment linings. However, the maximum values of stress and displacement showed differences from segment linings. The stress distribution of the continuous lining modeled as a shell type has a stress distribution that has continuity in the 3D cylindrical shape, but the segment lining is concentrated outside the segment, and the largest stress occurs at the location where the contact surface between the segment and the ring is concentrated. This intermittent and localized stress distribution shows an increasing as the ovality of the lining increases at seismic waves. The ovality at which the increase in stress distribution begins to show irregularity and localization is about 150‰. Ovality of 150‰ is an unrealistic value that cannot represent actual lining deformation. Therefore, the ovality of the segment lining increase with depth, but it does not have a significant impact on the stability caused by seismic load.

• Tuberculosis and Respiratory Diseases
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• v.42 no.4
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• pp.555-568
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• 1995

Background: It is most physiologic to measure the diffusing capacity of the lung by using oxygen, but it is so difficult to measure partial pressure of oxygen in the capillary blood of the lung that in clinical practice it is measured by using carbon monoxide, and single-breath diffusing capacity method is used most widely. However, since the process of withholding the breath for 10 seconds after inspiration to the total lung capacity is very hard to practice for patients who suffer from cough, dyspnea, etc, the intra-breath lung diffusing capacity method which requires a single exhalation of low-flow rate without such process was devised. In this study, we want to know whether or not there is any significant difference in the diffusing capacity of the lung measured by the single-breath and intra-breath methods, and if any, which factors have any influence. Methods: We chose randomly 73 persons without regarding specific disease, and after conducting 3 times the flow-volume curve test, we selected forced vital capacity(FVC), percent of predicted forced vital capacity, forced expiratory volume within 1 second($FEV_1$), percent of forced expiratory volume within 1 second, the ratio of forced expiratory volume within 1 second against forced vital capacity($FEV_1$/FVC) in test which the sum of FVC and $FEV_1$ is biggest. We measured the diffusing capacity of the lung 3 times in each of the single-breath and intra-breath methods at intervals of 5 minutes, and we evaluated which factors have any influence on the difference of the diffusing capacity of the lung between two methods[the mean values(ml/min/mmHg) of difference between two diffusing capacity measured by two methods] by means of the linear regression method, and obtained the following results: Results: 1) Intra-test reproducibility in the single-breath and intra-breath methods was excellent. 2) There was in general a good correlation between the diffusing capacity of the lung measured by a single-breath method and that measured by the intra-breath method, but there was a significant difference between values measured by both methods($1.01{\pm}0.35ml/min/mmHg$, p<0.01) 3) The difference between the diffusing capacity of the lung measured by both methods was not correlated to FVC, but was correlated to $FEV_1$, percent of $FEV_1$, $FEV_1$/FVC and the gradient of methane concentration which is an indicator of distribution of ventilation, and it was found as a result of the multiple regression test, that the effect of $FEV_1$/FVC was most strong(r=-0.4725, p<0.01) 4) In a graphic view of the difference of diffusing capacity measured by single-breath and intra-breath method and $FEV_1$/FVC, it was found that the former was divided into two groups in section where $FEV_1$/FVC is 50~60%, and that there was no significant difference between two methods in the section where $FEV_1$/FVC is equal or more than 60% ($0.05{\pm}0.24ml/min/mmHg$, p>0.1), but there was significant difference in the section, less than 60%($-4.5{\pm}0.34ml/min/mmHg$, p<0.01). 5. The diffusing capacity of the lung measured by the single-breath and intra-breath method was the same in value($24.3{\pm}0.68ml/min/mmHg$) within the normal range(2%/L) of the methane gas gradient, and there was no difference depending on the measuring method, but if the methane concentration gradients exceed 2%/L, the diffusing capacity of the lung measured by single-breath method became $15.0{\pm}0.44ml/min/mmHg$, and that measured by intra-breath method, $11.9{\pm}0.51ml/min/mmHg$, and there was a significant difference between them(p<0.01). Conclusion: Therefore, in case where $FEV_1$/FVC was less than 60%, the diffusing capacity of the lung measured by intra-breath method represented significantly lower value than that by single-breath method, and it was presumed to be caused largely by a defect of ventilation-distribution, but the possibility could not be excluded that the diffusing capacity of the lung might be overestimated in the single-breath method, or the actual reduction of the diffusing capacity of the lung appeared more sensitively in the intra-breath method.

• Journal of Nutrition and Health
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• v.46 no.1
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• pp.50-60
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• 2013

The aims of this study were to estimate daily intake of macrominerals from beverages, liquid teas, and liquid coffees and to evaluate their potential health risks for Korean children and adolescents (1-to 19 years old). Assessment of dietary intake was conducted using the actual level of sodium, calcium, phosphorus, potassium, and magnesium in non-alcoholic beverages and (207 beverages, 19 liquid teas, and 24 liquid coffees) the food consumption amount drawn from "The Fourth Korea National Health and Nutrition Examination Survey (2007-2009)". To estimate the dietary intake of non-alcoholic beverages, 6,082 children and adolescents (Scenario I) were compared with 1,704 non-alcoholic beverage consumption subjects among them (Scenario II). Calculation of the estimated daily intake of macrominerals was based on point estimates and probabilistic estimates. The values of probabilistic macromineral intake, which is a Monte-Carlo approach considering probabilistic density functions of variables, were presented using the probabilistic model. The level of safety for macrominerals was evaluated by comparison with population nutrient intake goal (Goal, 2.0 g/day) for sodium, tolerable upper intake level (UL) for calcium (2,500 mg/day) and phosphorus (3,000-3,500 mg/day) set by the Korean Nutrition Society (Dietary Reference Intakes for Koreans, KDRI). For total children and adolescents (Scenario I), mean daily intake of sodium, calcium, phosphorus, potassium, and magnesium estimated by probabilistic estimates using Monte Carlo simulation was, respectively, 7.93, 10.92, 6.73, 23.41, and 1.11, and 95th percentile daily intake of those was, respectively, 28.02, 44.86, 27.43, 98.14, and 3.87 mg/day. For consumers-only (Scenario II), mean daily intake of sodium, calcium, phosphorus, potassium, and magnesium estimated by probabilistic estimates using Monte Carlo simulation was, respectively, 19.10, 25.77, 15.83, 56.56, and 2.86 mg/day, and 95th percentile daily intake of those was, respectively, 62.67, 101.95, 62.09, 227.92, and 8.67 mg/day. For Scenarios I II, sodium, calcium, and phosphorus did not have a mean an 95th percentile intake that met or exceeded the 5% of Goal and UL.