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Variation of Liquid to Gas Ratio and Sulfur Oxide Emission Concentrations in Desulfurization Absorber with Coal-fired Thermal Power Plant Outputs (석탄화력 발전설비의 출력에 따른 탈황 흡수탑 액기비와 황산화물 배출농도 변화에 대한 연구)

  • Kim, Kee-Yeong;Moon, Seung-Jae
    • Plant Journal
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    • v.14 no.4
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    • pp.39-47
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    • 2018
  • In this research, when the output of the standard coal-fired thermal power plant operating continuously at the rated output of 500 MW is changed to operate at 300 to 500 MW, the amount of sulfur oxide produced and the amount of sulfur oxide in the absorption tower of desulfurization equipment and proposed an extra liquid to gas ratio improvement inversely proportional to the output. In order to calibrate the combustion efficiency at low power, the ratio of sulfur oxides relative to the amount of combustion gas is increased as the excess air ratio is increased. When the concentration of sulfur oxide at the inlet of the desulfurization absorber was changed from 300 to 500 ppm along with the output fluctuation. The liquid to gas ratio of limestone slurry and combustion gas was changed from 10.99 to 16.27. Therefore, if the concentration of sulfur oxides with output of 300 MW is x, The following correlation equation is recommended for the minimum required flow rate of slurry for the reduction of surplus energy due to the increase of the liquid weight at low load. $y1[m^3/sec]=0.11x+3.74$

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Ground Subsidence Risk Ratings for Pre-excavation (굴착 전 지반함몰 예측을 위한 위험등급 분류)

  • Ihm, Myeong-Hyek;Shin, Sang-Sik;Kim, Woo-Seok;Kim, Hak Joon
    • The Journal of Engineering Geology
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    • v.28 no.4
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    • pp.553-563
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    • 2018
  • The recent increase of ground subsidence in Korea requires the development of technology for predicting the possibility of ground subsidence. Eighteen parameters affecting the ground subsidence for pre-excavation are classified into 6 categories considering ground types, groundwater, and external factors. Eighteen parameters consists of a table which gives ground subsidence risk ratings for pre-excavation(GSRp). Certain scores are given to these parameters after they are divided into several classes considering the importance and the credibility of parameters and the engineering judgements of the authors. Because of the difference of ground subsidence factors depending on the ground and field conditions, weighting factors for the individual factor and for the each category are multiplied. Weighting factors are calculated from citation frequencies of influencing factors. Ground subsidence risk ratings for pre-excavation can be quantified by considering the individual score of each parameter and weighting factors for the individual factor and for the each category. The suggested GSRp tables obtained from this study are expected to be used by engineers for the estimation of ground subsidence risk ratings for pre-excavation sites.

A Study on the Topology Optimization of Nail Arrangement using Stiffened Shape Density (보강 형상밀도를 이용한 네일 배치의 위상최적화 연구)

  • Cho, Chung-Sik;Song, Young-Su;Lee, Su-Gon;Woo, Jae-Gyung;Choi, Woo-Il
    • The Journal of Engineering Geology
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    • v.28 no.4
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    • pp.605-618
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    • 2018
  • Korea follows the slope design criteria during construction. It was enacted by the Ministry of Land, Transport and Maritime Affairs. There are cases where the Soil-nail is designed as a measure to secure slope stability. The arrangement of the soil-nail may be arranged at equal intervals or may be arranged differently depending on the soil failure model. The optimum design of the countermeasure method is determined by securing stability of the slope through optimization of dimensions and shape. However, when uniform nails are placed at low elevations in slopes, the standard safety factor is exceeded, which may hinder economic design. It is preferable to arrange the reinforcement of the nails over the entire slope. When the horizontal spacing of the nails was topology optimized according to the slope height, it was possible to minimize the amount of reinforcement while satisfying the standard safety factor. Since the active load is reduced in the section where the slope height is lowered, the safety factor after reinforcement may be excessively increased. Therefore, the phase optimization method is proposed as an economical optimal design method using the reinforcing shape density. In addition, a relational expression was designed to optimize the horizontal spacing by slope height.

The Validation of the Play Participation Attitude Scale for Parents of Preschoolers (영유아 부모의 놀이참여태도 척도 타당화 연구)

  • Lee, So-yean;Wui, Yeong-hee;Yoo, Jae-ryoung;Chyung, Yun-joo;Lee, Young-ae;Kim, Lee-jin
    • Korean Journal of Play Therapy
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    • v.21 no.4
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    • pp.491-507
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    • 2018
  • The purpose of this study is to validate the Play Participation Attitude Scale for parents of preschoolers, which was developed by the Delphi survey. 447 parents of 9 daycare centers in Seoul and Incheon were recruited for this study and, finally, data from 339 parents were used to perform exploratory factor analysis, confirmatory factor analysis, correlation analysis, multiple regression analysis, and reliability analysis. The results of the study are as follows. First, factor analyses revealed that the global fit of the sensitively play (7 items), responsively play (6 items), and delightfully play(7 items) three-factor model was good. Second, the internal consistency of the Play Participation Attitude Scale was good. Third, there was a statistically significant positive correlation between the current scale and the parents' playfulness scale, indicating concurrent validity. Finally, higher scores of the Play Participation Attitude Scale and its three factors significantly predicted lower scores of parenting stress and higher scores of the preschoolers' self-control ability. These findings revealed that this new measure to be both valid and reliable and specifically suggests what kind of attitude is appropriate for parents to adopt when participating in preschoolers' play.

A study on estimation of agricultural water usage in river consider hydrological condition (수문상황을 고려한 하천에서의 농업용수 사용량추정 연구)

  • Kwak, Jaewon
    • Journal of Korea Water Resources Association
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    • v.54 no.5
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    • pp.311-320
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    • 2021
  • The agricultural water, which occupy about 61% of total water usage in the South Korea, is significantly objective to archieve effecitive water resources management. The objective of the study is to suggest a simple method in actual practice that could be used to estimate agricultural water usage in river considering hydrological condition. Historical record of agricultural water usage and runoff, which take account for hydrological condition of the basin, were obtained for totally 27 river basins. As the result, the high threshold value of the agricultural water usage rates compared to maximum usage amount has a particular correlations to the percent of normal year runoff for last 2 month, and threshold line of agricultural water usage rates was derived using the quantile regressions. Finally, two dimensionless threshold line and empirical formulas that described the correlation between the percent of normal year runoff for last 2 month and the agricultural water usage rate compared to maximum usage amount were derived. Also, the simple criteria to select which line and formula based on the characteristics of the basins was suggested but it need further studies. The result of the study could be used as an elemantary data in actual practice for water resoureces management.

Estimation of Frequency of Storm Surge Heights on the West and South Coasts of Korea Using Synthesized Typhoons (확률론적 합성태풍을 이용한 서남해안 빈도 해일고 산정)

  • Kim, HyeonJeong;Suh, SeungWon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.5
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    • pp.241-252
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    • 2019
  • To choose appropriate countermeasures against potential coastal disaster damages caused by a storm surge, it is necessary to estimate the frequency of storm surge heights estimation. As the coastal populations size in the past was small, the tropical cyclone risk model (TCRM) was used to generate 176,689 synthetic typhoons. In simulation, historical paths and central pressures were incorporated as a probability density function. Moreover, to consider the typhoon characteristics that resurfaced or decayed after landfall on the southeast coast of China, incorporated the shift angle of the historical typhoon as a function of the probability density function and applied it as a damping parameter. Thus, the passing rate of typhoons moving from the southeast coast of China to the south coast has improved. The characteristics of the typhoon were analyzed from the historical typhoon information using correlations between the central pressure, maximum wind speed ($V_{max}$) and the maximum wind speed radius ($R_{max}$); it was then applied to synthetic typhoons. The storm surges were calculated using the ADCIRC model, considering both tidal and synthetic typhoons using automated Perl script. The storm surges caused by the probabilistic synthetic typhoons appear similar to the recorded storm surges, therefore this proposed scheme can be applied to the storm surge simulations. Based on these results, extreme values were calculated using the Generalized Extreme Value (GEV) method, and as a result, the 100-year return period storm surge was found to be satisfactory compared with the calculated empirical simulation value. The method proposed in this study can be applied to estimate the frequency of storm surges in coastal areas.

Design of Remote Early Dementia Diagnosis Systems (원격 치매 조기 진단 시스템 설계)

  • Choi, Jongmyung;Jeon, Gyeong-Suk;Kim, Sunkyung;Choi, Jungmin;Rhyu, Dong Young;Yoon, Sook
    • Journal of Internet of Things and Convergence
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    • v.6 no.4
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    • pp.27-32
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    • 2020
  • Along with the aging of the population, the number of dementia patients is increasing, and the social and economic burden is also increasing. Currently, the effective way to manage dementia patients is to identify patients with dementia early. However, in rural and island areas where medical staff are scarce, there is a problem that it is difficult to visit a hospital and get an early examination. Therefore, we propose a remote early detection system for dementia to solve the problems. The remote dementia early diagnosis system is a system that allows a patient to receive examination and treatment from a remote dementia expert using remote medical technology based on real-time image communication. The remote early diagnosis system for dementia consists of a local client system used by medical staff at health centers in the island, an image server that transmits, stores and manages images, and an expert client used by remote dementia experts. The local client subsystem satisfies the current medical law's remote collaboration by allowing the patient to use it with the health center's medical staff. In addition, expert clients are used by dementia experts, and can store/manage patient information, analyze patient history information, and predict the degree of dementia progression in the future.

Multi-fidelity Data-fusion for Improving Strain accuracy using Optical Fiber Sensors (이종 광섬유 센서 데이터 융합을 통한 변형률 정확도 향상 기법)

  • Park, Young-Soo;Jin, Seung-Seop;Yoo, Chul-Hwan;Kim, Sungtae;Park, Young-Hwan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.40 no.6
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    • pp.547-553
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    • 2020
  • As aging infrastructures increase along with time, the efficient maintenance becomes more significant and accurate responses from the sensors are pre-requisite. Among various responses, strain is commonly used to detect damage such as crack and fatigue. Optical fiber sensor is one of the promising sensing techniques to measure strains with high-durability, immunity for electrical noise, long transmission distance. Fiber Bragg Grating (FBG) is a point sensor to measure the strain based on reflected signals from the grating, while Brillouin Optic Correlation Domain Analysis (BOCDA) is a distributed sensor to measure the strain along with the optical fiber based on scattering signals. Although the FBG provides the signal with high accuracy and reproducibility, the number of sensing points is limited. On the other hand, the BOCDA can measure a quasi-continuous strain along with the optical fiber. However, the measured signals from BOCDA have low accuracy and reproducibility. This paper proposed a multi-fidelity data-fusion method based on Gaussian Process Regression to improve the fidelity of the strain distribution by fusing the advantages of both systems. The proposed method was evaluated by laboratory test. The result shows that the proposed method is promising to improve the fidelity of the strain.

Effect of Long-term Care Worker's Person-Centered Care on Service Quality of long term care facility -Focusing on mediating effects of long term care worker's emotional labor and job satisfaction- (요양보호사의 인간중심케어와 서비스 질의 관계 -요양보호사의 감정노동과 직무만족의 매개효과 중심-)

  • Song, Myeong-Seop;Rhee, Young-Sun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.3
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    • pp.476-484
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    • 2021
  • In this study, we analyze the relationships between long-term care workers' person-centeredness and job satisfaction, emotional labor, and service quality. Self-administered questionnaires were used to collect data from 460 long-term care workers in long-term care facilities. In the research model, person-centered care was verified using independent variables, with emotional labor (surface behavior, internal behavior) and job satisfaction applied as parameters, and service quality applied as a dependent variable. The results of this study are as follows. First, the fit of the model is good. Second, the implicit behavior of emotional labor is found to be an important factor affecting service quality. Also, emotional labor is an important mediator, improving the value of person-centered care and service quality. There is a positive correlation between internal behavior and service quality, and a negative correlation between surface behavior and service quality. Third, emotional labor (surface behavior, internal behavior) is the most influential variable in terms of service quality. The results of this study demonstrate the necessity to pay clinical and academic attention to person-centered care in terms of long-term care workers' emotional labor and service quality.

Factors contributing to the reduction of sodium intake by food manufacture and cooking venues according to the national sodium reduction policies (국가 나트륨 저감화 정책에 따른 생산 및 조리 주체별 나트륨 섭취 감소 기여 요인 분석)

  • Kim, Kirang;Park, Sohyun;Kim, Jee Young
    • Journal of Nutrition and Health
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    • v.53 no.6
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    • pp.648-662
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    • 2020
  • Purpose: Sodium intake is persistently decreasing because of the government's sodium reduction policy. This study aimed to identify foods and dishes that contributed to the reduction of sodium intake and evaluate the effects of the sodium reduction policy. Methods: The subjects were 57,809 participants in the Korea National Health and Nutrition Survey from 2010 to 2017. To identify food and dish sources of sodium intake, the food and dish groups were classified into 23 and 21 groups, respectively. Foods and dishes that contributed to sodium intake were categorized according to the production and cooking venues: production by manufacturers, home cooking, cooking at catering service, and restaurant cooking. Results: Sodium intake was 4,876 mg in 2010 to 3,477 mg in 2017, showing a 29.7% decrease in intake in 2010. Sodium intake was decreased mainly in foods produced by manufacturers and home-cooked foods. The main contributory factors to sodium from the food and dish groups differed according to the food manufacturer and cooking venue. The kimchi produced by manufacturers, cooked soup/tang/jjigae/hotpot at home and catering services, and cooked noodles/dumplings in restaurants were the main contributors to the sodium intake. Conclusion: The type of foods and dishes that contribute to sodium intake tended to expand over the years from specific foods and dishes to various groups of foods and dishes. These results provide evidence for the development and production of low-salt foods and dietary education related to low-salt intake.