• 제목/요약/키워드: Mixed Calculations

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Raman Spectroscopy and Molecular Modeling Study on the CH4 and SF6 Mixture Gas Hydrate Growth Behavior (라만 분광학과 분자모델링을 이용한 메탄 및 육불화황 혼합 가스 하이드레이트 성장 거동 연구)

  • Lim, Jun-Heok;Lee, Ju Dong;Park, Sung Soo;Eom, Ki Heon;Won, Yong Sun
    • Clean Technology
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    • 제19권4호
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    • pp.476-480
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    • 2013
  • The growth behavior of $CH_4$ and $SF_6$ mixture gas hydrate has been investigated by a combined approach of Raman spectroscopy and molecular modeling. Raman spectroscopy results presented that when $CH_4$ is used only, $CH_4$ guest molecule is inserted first into the large cavity of the host structure built by $H_2O$ molecules and then into the small cavity to stabilize the whole gas hydrate structure. In the other hand, when $SF_6$ is mixed together, $SF_6$ is favored over (or competing with) $CH_4$ in being inserted into the large cavity and the small cavity still prefers $CH_4$ insertion. The calculations of binding energies clearly supported this. While $SF_6$ has a binding energy of -26.9 kcal/mol a little lower than -24.2 kcal/mol of $CH_4$ in the large cavity, $SF_6$ and $CH_4$ has 1.2 kcal/mol and -22.0 kcal/mol, respectively, in the small cavity. It indicates that the sizable $SF_6$ is not preferred in the small cavity but has a relative energetic advantage over $CH_4$ in the large cavity.

A Study on the Changes in Heavy Metal Emissions when Using Mixed Fuel in a Thermal Power Plant (화력발전소의 혼합연료 사용에 따른 중금속 배출량 변화 연구)

  • Song, Youngho;Kim, Ok;Park, Sanghyun;Lee, Jinheon
    • Journal of Environmental Health Sciences
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    • 제44권1호
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    • pp.63-75
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    • 2018
  • Objectives: The aim of this research is to explore the total heavy metals from a coal-fired power plant burning bituminous coal with wood pellets due to the implementation of the Renewable Portfolio Standard policy (RPS, 10% of electricity from renewable energy resources by 2023). Methods: The research was carried out by collecting archival data and using the USEPA's AP-42 & EMEP/EEA compilation of emission factors for use in calculating emissions. The Monte Carlo method was also applied for carrying out the calculations of measurement uncertainty. Results: In this paper, the results are listed as follows. Sb was measured at 110 kg (2015) and calculated as 165 kg (2019) and 201 kg (2023). Cr was measured at 1,597 kg (2015) and calculated as 1,687 kg (2019) and 1,728 kg (2023). Cu was measured at 2,888 kg (2015) and calculated as 3,133 kg (2019) and 3,264 kg (2023). Pb was measured at 2,580 kg (2015) and calculated as 2,831 kg (2019) and 2,969 kg (2023). Mn was measured at 3,011 kg (2015) and calculated as 15,034 kg (2019) and 23,014 kg (2023). Hg was measured at 510 kg (2015) and calculated as 513 kg (2019) and 537 kg (2023). Ni was measured at 1,720 kg (2015) and calculated as 1,895 kg (2019) and 1,991 kg (2023). Zn was measured at 7,054 kg (2015) and calculated as 9,938 kg (2019) and 11,778 kg (2023). Se was measured at 7,988 kg (2015) and calculated as 7,663 kg (2019) and 7,351 kg (2023). Conclusion: This shows that most heavy metals would increase steadily from 2015 to 2023. However, Se would decrease by 7.9%. This analysis was conducted with EMEP/EEA's emission factors due to the limited emission factors in South Korea. Co-firewood pellets in coal-fired power plants cause the emission of heavy metals. For this reason, emission factors at air pollution control facilities would be presented and the replacement of wood pellets would be needed.

A-team Based Approach for Reactive Power/Voltage Control Considering Steady State Security Assessment (정태 안전성 평가를 고려한 무효전력 전압제어를 위한 A-team기반 접근법)

  • Kim, Doo-Hyun
    • Journal of the Korean Society of Safety
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    • 제11권2호
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    • pp.150-159
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    • 1996
  • In this paper, an A-team(Asynchronous Team ) based approach for Reactive power and volage control considering static security assessment in a power system with infrastructural deficiencies is proposed. Reactive power and voltage control problem is the one of optimally establishing voltage level given several constraints such as reactive generation, voltage magnitude, line flow, and other switchable reactive power sources. It can be formulated as a mixed-integer linear programming(MILP) problem without deteriorating of solution accuracy to a certain extent. The security assessment is to estimate the relative robustness of the system in Its present state through the evaluation of data provided by security monitoring. Deterministic approach based on AC load flow calculations is adopted to assess the system security, especially voltage security. A security metric, as a standard of measurement for power system security, producting a set of discrete values rather than binary values, is employed. In order to analyze the above two problems, reactive power/voltage control problem and static security assessment problem, in an integrated fashion for real-time operations, a new organizational structure, called an A-team, is adopted. An A-team is an organization for agents which ale all autonomeus, work in parallel and communicate asynchronously, which is well-suited to the development of computer-based, multi-agent systems for operations. This A-team based approach, although it is still in the beginning stage, also has potential for handling other difficult power system problems.

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Annual cycles of nutrients and dissolved oxygen in a nutrient-rich temperate coastal bay, Chinhae Bay, Korea (영양염류가 풍부한 온대 해역 내만(한국, 진해만)에서의 영양염류와 용존산소의 연변화)

  • HONG, GI HOON;KIM, KYUNG TAE;PAE, SE JIN;KIM, SUK HYUN;LEE, SOO HYUNG
    • 한국해양학회지
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    • 제26권3호
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    • pp.204-222
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    • 1991
  • The annual cycles of plant major nutrients and dissolved oxygen in a nutrients-rich semi-enclosed coastal inlet, chinhae Bay, of the southern coast of the Korean Peninsula are first presented. The water column of the bay is stratified during summer (April-late September) and well0mixed during winter (October-March). During the summer stratification period, dissolved oxygen contents exceed 400uM in the surface but diminish to less than 50uM in the near bottom waters, which often results in an anoxic environment in the inner part of Chinhae Bay. After the breakdown of the stratification in October, dissolved oxygen concentration remains undersaturated until February. The evidence of allochthonous input of N-nutrients throughout the year is readily seen in the water column: however. crude budget calculations show that the nutrients are efficiently utilized within the bay ecosystem, and that export of the nutrients from the bay to the shelf must be negligible. There is no sign of the enrichment of the nutrients in the water column. The eutrophication phenomenon sensu stricto is not observed in chinhae Bay. Using the standing stock of dissolved oxygen and estimation of the oxygen fluxes across the air-sea boundary, a benthic oxygen respiration rate during winter is estimated conservatively at 21-24 mmol Cm/SUP -2/d/SUP -1/. this oxygen respiration rate accounts for about 20% of the total phytoplankton production in winter.

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Effects of Typhoon and Mesoscale Eddy on Generation and Distribution of Near-Inertial Wave Energy in the East Sea (동해에서 태풍과 중규모 소용돌이가 준관성주기파 에너지 생성과 분포에 미치는 영향)

  • SONG, HAJIN;JEON, CHANHYUNG;CHAE, JEONG-YEOB;LEE, EUN-JOO;LEE, KANG-NYEONG;TAKAYAMA, KATSUMI;CHOI, YOUNGSEOK;PARK, JAE-HUN
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • 제25권3호
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    • pp.55-66
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    • 2020
  • Near-inertial waves (NIW) which are primarily generated by wind can contribute to vertical mixing in the ocean. The energetic NIW can be generated by typhoon due to its strong wind and preferable wind direction changes especially on the right-hand side of the typhoon. Here we investigate the generation and distribution of NIW using the output of a real-time ocean forecasting system. Five-year model outputs during 2013-2017 are analyzed with a focus on cases of energetic NIW generation by the passage of three typhoons (Halong, Goni, and Chaba) over the East Sea. Calculations of wind energy input (${\bar{W}}_I$), and horizontal kinetic energy in the mixed layer (${\bar{HKE}}_{MLD}$) reveal that the spatial distribution of ${\bar{HKE}}_{MLD}$, which is strengthened at the right-hand side of typhoon tracks, is closely related with ${\bar{W}}_I$. Horizontal kinetic energy in the deep layer (${\bar{HKE}}_{DEEP}$) shows patch-shaped distribution mainly located at the southern side of the East Sea. Spatial distribution of ${\bar{HKE}}_{DEEP}$ shows a close relationship with negative relative vorticity regions caused by warm eddies in the upper layer. Monthly-mean ${\bar{HKE}}_{MLD}$ and ${\bar{HKE}}_{DEEP}$ during a typhoon passing over the East Sea shows about 2.5-5.7 times and 1.2-1.6 times larger values than those during summer with no typhoons, respectively. In addition, their magnitudes are respectively about 0.4-1.0 and 0.8-1.0 times from those during winter, suggesting that the typhoon-induced NIW can provide a significant energy to enhance vertical mixing at both the mixed and deep layers during summer.

The Influence of Food Habits on Body Stature of Children (어린이의 식습관(食習慣)이 체위(體位)에 미치는 영향(影響)에 관한 연구(硏究))

  • Lee, Mi-Suk;Mo, Su-Mi
    • Journal of Nutrition and Health
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    • 제9권1호
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    • pp.7-15
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    • 1976
  • The Purpose of this study was to determine every possible correlation between food habits and body statures of primary school children, aged ten years old. This study was conducted from July to October of 1975. In July, prepared questionaires concerning life style, anthropometry, food preference, and food behavior were distributed through school teachers to 425 children; 219 boys and 206 girls, in the 5th grade of three elementary schools in the city of Seoul. Then, in October, when subjects had been classified into underweight/obese by statistical analysis, mothers of obese or underweight children were interviewed by the authors to determine weaning history, daily food consumption of their children, and opinions of various snacks for children. Analysis of results in terms of correlation coefficient, chisquare test and percentage calculations, are as follows: 1. Physical growth and development Boys Girls Height (cm) $134.8{\pm}5.74\;134.4{\pm}5.97$ Weight (kg) $30.0{\pm}4.27\;29.5{\pm}5.16$ Chestgirth (cm) $64.1{\pm}3.59\;63.3{\pm}3.81$ Arm circumference (cm) $18.3{\pm}1.61\;18.2{\pm}1.70$ Triceps skinfold thickness (mm) $10.9{\pm}5.13\;12.7{\pm}4.86$ Various indices of nutrition such as relative weight, relative chestgirth, $R{\ddot{o}}hrer's$ index, Kaup index, Vervaeck index were determined. 2. Food habits 1) Food $preference{\cdots}{\cdots}A$ varying number of foods were selected from 60 items were accepted. It was found that the food which children liked best was fruit and snacks were popular one. Lowest ranking among LIKED foods were from strongly flavored vegetables and organ meat. In general, girls had more food dislikes than did boys. Selected as liked foods were fruits, rice noodle soup, biscuits, and peanuts. Disliked foods were liver, green onions, onions, green pepper, mushrooms, oysters, shellfish, and pork. Items which children never ate before were liver, mushrooms, fish cake, boiled rice mixed with sorghum, mayonnaise, and fresh water firsh. Reasons which children gave for dislike were undesirable flavor and odor. 2) Food $behavior{\cdots}{\cdots}It$ was found that boys liked sweet and salty flavors more than did the girls who more often liked sour flavor. The majority of children enjoyed evening meals more than lunch and breakfast. A number of children skipped breakfast because of lack of appetite or lack of time before going to school. Snacks were the most popular food, especially among girls. Their snacking habits were formed by the encouragement of the mother, and the relieve boredom. Educational backgrounds of mothers and family economical levels of children were remarkable correlated with mothers' attitudes toward feeding of children. There were several interesting findings relating body stature to some other responses; such as that the obese child has a small number of brothers, higher birth order, higher educated mothers and higher family cultural background. It was also discovered that food perference, except for fat and oil group foods was not related to body stature. Sweet taste was liked best and pepperly taste was mostly disliked. Sour taste was popular in the group of underweight. Underweight children were more finicky, disliked snacking, and didn't get much attention from their mothers. 3) Correlation between body stature and nutrition during their infancy. The majority of children, both from obese and underweight, were breast fed as infant. Twenty five per cent of obese children and 17.4 per cent of underwight children started weaning at $1{\sim}6$ months old. The most popular supplemental food of weaning was cereal gruel for the obese group, while boiled white rice and cereal gruel were most common for the underweight group. Highly significant relationships were found between stature of parents and their children. In the obese group 47.8 per cent of fathers and 45.9 per cent of mothers were overweight; however, none of the fathers and only one mother was found to be underweight. In daily food consumption patterns, meals consisting of bread or noodle were popular in the obese group but disliked by the underweight group. The study found clear contrast in that the obese group liked meat and fish while the underweight group liked fruits and vegetables, especially kimchee. The obese children desired to eat cereal foods, milk and milk products, and fat foods while the underweight group desired to eat fruits and vegetables. Frequency of snacks per day was much greater in the obese group. Foods which mothers believed to be good for the health were carrots, cucumbers, fruits, milk, potatoes, sweet potatoes, and breads, while sweet foods such as candies, drinks. chocolate were considered not good for the teeth. Watching television was not significantly related to statures of children. Most significant relationships were found beween frequencies of family guest meals/and eating-out, and children's statures. Nutritional problems which have been considered for the malnourished children in addition to those of children who have a tendency toward obesity, must be taken into consideration in the development of proper nutrition education through the channels of regular school teaching and teaching by parents in the homes. Korean standards of anthropometric measurements for children should be revised, current measurements show much higher figures than present Korean standards.

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