• Title/Summary/Keyword: Floor heating

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Computer Simulation for the Thermal Analysis of the Energy Storage Board (에너지 축열보드 열해석을 위한 컴퓨터 수치해석)

  • 강용혁;엄태인;곽희열
    • Journal of Energy Engineering
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    • v.8 no.2
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    • pp.224-232
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    • 1999
  • Latent heat storage system using micro-encapsuled phase change material is effective method for floor heating of house and building. The temperature profile in capsule block and flow rate of hot water are important parameters for the development of heat storage system. In the present study, a mathematical model based on 3-D, non-steady state, Navier-Stokes equations, scalar conservation equations and turbulence model ($\kappa$-$\varepsilon$), is used to predict the temperature profiles in capsule and the velocity vectors in hot water pipe. The multi-block grids and fine grids embedding are used to join the circle in hot water pipe and square in capsule block. The phase change process of the capsule is quite complex not only because the size of phase change material is very small, but also because phase change material is mixed with the cement to form thermal storage block. In calculation, it's assumed that the phenomena of phase change is limited only the thermal properties of phase change material and the change of boundary is not happened in capsule. The purpose of this study is to calculate the temperature profiles in capsule block and velocity vectors in hot water pipe using the numerical calculation. Two kinds of thermal boundary condition were considered, the first (case 1) is the adiabatic condition for the both outside surfaces of the wall, the second (case 2) is the case in which one surface is natural convection with atmosphere and another surface is adaibatic. Calculation results are shown that the temperature profile in capsule block for case 1 is higher than that for case 2 due to less heat loss in adaibatic surface. Specially, in the domain of near Y=0, the difference of temperature is greater in case 1 than in case 2. The detailed experimental data of capsule block on the temperature profile and the thermal properties such as specific heat and coefficient of heat transfer with the various temperature are required to predict more exact phenomena of heat transfer.

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Analysis of Urban Dweller's Demand for Housing facilities to Settle Down in Rural Area (농촌정주를 위한 도시민 농촌주택 시설 수요분석)

  • Kim, Myo-Jung;Kim, Hye-Min;Heo, Jun
    • Journal of Korean Society of Rural Planning
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    • v.13 no.2
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    • pp.63-74
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    • 2007
  • This study aims to develop rural house maintenance technique by researching and analyzing the demand for rural house by urban retirees or urbanites who are planning to retire. The target for the survey consisted of urban retirees or urbanites who are planning to retire at the ages between 40 and 65, and were divided into group A, the attendants in rural-related education, and group B, the non-attendants in rural-related education. The contents of the survey included the plan and purpose for rural settlement, the utilization form or residential form of rural house and its expected size, necessary in-house facilities, necessary community facilities, improvement and maintenance factors of rural house, political and legal support for the application of rural house maintenance, etc. The results findings of this study are as follows; 1)For both group, the major purpose of rural settlement appeared to be 'for rural life', utilization form of rural house to be 'acquired ownership or use of empty house', residential form to be 'cohabitation', expected size to be 'under $20{\sim}30$ pung', and expenditure to be 'under $50{\sim}100\;million$'. 2)Most wanted necessary in-house facilities included backyard, multipurpose storage room for group A, and backyard, garden for group B. Necessary community facilities included boardwalk, sewage disposal unit for group A, and boardwalk, shop for group B. 3)Improvement factor for rural house showed 'poor insulation' as first factor for both groups, and for maintenance factor, 'backyard', 'under-floor heating' for group A, and 'environmental-friendly materials', 'backyard' for group B. 4)Most wanted overall political and legal support included 'support on land and real estate supply' for group A, and 'medical and transportation service' for group B. For both group, most wanted support when purchasing a house included 'provision of information on house and realestate purchase', and for legal support, 'legal support for guaranteed house and maintenance' as first factor. The results of this study could be utilized to restructure the rural residence, which would meet the diverse demand of both rural residents and urbanites by providing an opportunity for urbanites to enjoy rural life.

A Study on the Alteration of the Collective Housing- in Modern Times, Korea - Focused on the Settled Process of Apartment Housing - (한국(韓國) 공동주택(共同住宅) 변천(變遷)에 관(關)한 고찰(考察) - 근대기(近代期) 아파트의 정착과정(定着過程)을 중심으로 -)

  • Chung, Soon-Young;Yoon, In-Suk
    • Journal of architectural history
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    • v.11 no.2 s.30
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    • pp.37-56
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    • 2002
  • The purpose of this study is to examine the changing process of the collective housing in Korea; focusing on the alteration process of the apartment housing, which became a representative housing type in Korea, nowadays. The alteration process of the apartment housing in Korea can be divided into three stages: the introduction stage, the trial stage and the settled stage. The introduction stage is the period between 1920, when the collective-housing buildings were constructed in Korea for the first time, and the Liberation of Korea(1945). The trial stage is the period between 1945 and 1975. During this period, common housing has been constructed. And the massive apartment buildings were started to be supplied after 1975. The settled stage is the period between 1975 and the present. The main scope of this study will be the introduction and trial stages, since a lot of in-depth studies have been executed on the settled stage. The history of the collective housing of Korea starts with City Housing of Seoul, in 1921. It is guessed that this housing was to be small-sized and row-housing type. The first-built, apartment-type building, in Korea, was Mikuni Apartment House, which was constructed as a boarding room of Mikuni Company. In the introduction stage, apartment buildings were built by Japanese architects, with Japanese housing style. Most of them were planned in dormitory type, and some of them were run as tenant houses. Most of them were constructed by bricks, but sometimes by timbers. Tadami was laid in every room and inside-corridor was located in the middle of the house. Although the major style of the apartment buildings was Japanese, the Korean dwellers of those apartments has been influencing the housing type of them. In the trial stage, apartment housing has been experienced in diverse ways. With the development of building technology, floor heating system was settled in apartment housing. This improved the amenities of apartment dwelling remarkably. Although some heterogeneous characteristics still remained in the apartments of Korea, in terms of housing style, the housing style of apartments has been changed into own style of Korea, in accordance with Korean people's life style. The results of this study give us some good implications regarding contemporary housing plan: First, if the unit size of a collective housing is small, the more space could be available for community activities. Second, when planning of collective housing, more concerns should be payed on surroundings. Third, more attention should be payed about low-rise apartment housing, and more land-friendly planning would be required.

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A Study on the Incidence of Carbon Monoxide Poisoning (연탄(煉炭)가스중독(中毒)의 발생실태(發生實態)에 관(關)한 연구(硏究))

  • Cho, Soo-Hun;Shin, Young-Soo;Lee, Doek-Hyoung;Kim, Yong-Ik;Yun, Dork-Ro
    • Journal of Preventive Medicine and Public Health
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    • v.18 no.1
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    • pp.1-11
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    • 1985
  • A decade ago a survey on the population-base incidence rate of anthracite coal gas (mainly carbon monoxide) poisonig in Seoul area was investigated, resulting in the incidence rate of 306/10,000 risk population and 1 death/10,000. Another survey on the carbon monoxide poisoning was investigated during 1 year period from Apr. 1983 to Mar. 1984. Total subjects of risk population were 67,740 households covering 353,287 persons. The major findings of this survey are as follows: 1. Household-base incidence rate was 8.4% spell-base 10.4%. 2. The incidence rate was the highest in houses having each of slate roof, cement wall, vinyl floor of bedroom and direct 'ondol' heating system. 3. Average 2.1 person was attacked from one incidence of the poisoning; severity-wise person-base incidence rates per 10,000 were 352 in mild poisoning, 54 in severe poisoning and 1.4 in death-overall incidence rate 407. Several facts were identified which supported that this figure was moderately underestimated. As the incidence of the poisoning is affected by socioeconomic and environmental factors, it is natural that one expects the incidence will decrease in proportion to genernal improvement of the above factors. Thus the results of these two surveys seemed preposterous. But further study suggested that the incidence rate (306/10,000) decade before had been significantly underestimated and corrected-rate should have been 478/10,000 level. 4. Age and sex distribution by the degree of the poisoning was uniform with little statistical difference; overall incidence rates by sex were 339/10,000 in male and 475/10,000 in female with significant statistical difference(p<.01). 5. 5.3% of the patients were treated at hospital or local clinic; 3.0% of the patients were hospitalized. Admission rate in comatose patient(severe poisoning) was 14.2%. In conclusion, carbon monoxide poisoning remains a major health problem by now.

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The Comparative Analysis of Drying-Conditions, -Rates, -Defects and Yield, and Heat-Efficiency in Solar-Dehumidification-Drying of Oaks With Those in Conventional Air-, Semi-Greenhouse Type solar-, and Kiln- Drying (참나무류(類)의 제습태양열건조(除濕太陽熱乾燥)의 조건(條件), 속도(速度), 결함(缺陷), 수율(收率) 및 열효율(熱效率)과 관행(慣行) 천연(天然), 반온실형(半溫室型) 태양열(太陽熱) 및 열기건조(熱氣乾燥)와의 비교(比較)·분석(分析))

  • Lee, Hyoung-Woo;Jung, Hee-Suk
    • Journal of the Korean Wood Science and Technology
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    • v.17 no.1
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    • pp.22-54
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    • 1989
  • Seasonal semi-greenhouse type solar-drying of 2.5cm-and 5.0cm-thick lumber of Quercus aliena Blume and Quercus variailis Blume was carried out to investigate the possibility of solar-drying of wood and to decide the active solar-drying period in Korea. In the active solar-drying period obtained solar-dehumidification, semi-greenhouse type solar-, air- and kiln-drying of 2.5cm -thick lumber of oaks were carried out to analyze drying-rates. -defects, and -yield in each drying-method and to calculate daily total absorbed solar-radiation the solar dryers. The energy balance equations were set up, considering all the energy requirements, to analyze the heat efficiencies of semi-greenhouse type solar and solar-dehumidification-dryer. In a seasonal drying the drying rate of semi-greenhouse type solar-dryer was highest in summer, and greater in fall, spring, and winter in order. Solar-drying time was 45% in summer to 50% in winter of the air-drying rime, and more serious drying-defects occurred in air-drying than in solar-drying. In the active solar-drying period. April, May, and June, the average drying rate in solar-dehumidification-drying was 1.0%/day and greater than 0.8%/day in semi-greenhouse type solar-drying. In solar-dehumidification-drying the time required to dry lumber to 10% moisture content was less than 60 days, and solar-dehumidification-drying showed the highest drying-yield, 65.01%, than the other drying methods. The daily total absorbed solar radiations were 8.51MJ on the roof collector and 6.22 MJ on the south wall collector. In the energy blance 69.48% of total energy input was lost by heat conduction through walls, roof. and floor 11.68% by heat leakage, 0.33% by heating the internal structures of the solar-dryer and 5.38% by air-venting. Therefore the heat efficiency of semi-greenhouse type solar-dryer 13.13%, was lower than that of solar-dehumidification-dryer, 14.04%. Solar-drying of lumber in Korea showed the possibility to reduce the air-drying-time in every season and the efficiency of solar-dehumidification drying was higher than that of semi-greenhouse type solar-drying.

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Application of HACCP for Hygiene Control in University Foodservice Facility - Focused on Vegetable Dishes (Sengchae and Namul) - (대학급식시설의 위생관리개선을 위한 HACCP 적용에 관한 연구 - 생.숙채류를 중심으로 -)

  • 허영수;이복희
    • Journal of Food Hygiene and Safety
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    • v.14 no.3
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    • pp.293-304
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    • 1999
  • The purpose of this study was to evaluate the microbiological quality, and to assure the hygienic safety of the food production in the university food service facility located in Seoul in accordance with the Hazard Analysis Critical Control Point(HACCP) concepts. In the hygienic state assessment of kitchen, it has revealed that it was very important to remove water from the kitchen floor and to establish standard method for disinfection of cooking utensils. And foodservice workers were required to have training program for the safe handling of food and utensils since they did treat food without hygienic gloves. The kitchen layout had to be improved because the near distance of table with heating unit and shelf might cause the growth of microorganisms when prepared food was kept on the shelf. In terms of the timetemperature measurement and microbiological quality assessment during each of the food production phases, most of sengchae (raw vegetable dish) and namul (cooked vegetable dish) were treated within danger zone for food safeness ($5~60^{\circ}C$). It has shown that the microbiological quality of raw materials was very much inferior at the time of receiving based on the TPC($10^{5}~10^{7}$), coliform($10^{3}~1O^{6}$), which was not acceptable level(TPC:$10^{6}$, coliform:$10^{3}$) suggested by Solberg. Microbiological growth has increased in the both of sengchae and namul considerably during most of food production phase. Therefore, it is extremely important to reduce holding and serving time and to avoid treating food within the danger zone for food safeness. In addition, the prevention of cross-contamination during mixing the ingredients with improper equipments and with insanitary treatments by workers was also important to keep the food safety in this speciqic university foodservice facility.

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Design of Chamber in Continuous Furnace for Uniform Temperature Distribution (균일 온도를 유지하는 연속 소성로 체임버의 설계)

  • Lee, Kwangju;Choi, Joon Hyeok;Jang, Han Seul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.11
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    • pp.5344-5351
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    • 2013
  • Chambers in a continuous furnace were designed. A chamber consists of inlets and outlets of nitrogen gas which is used to discharge burned gas and heating pipes (HP) which are used to keep temperature of fired materials at $1,300^{\circ}C$. Design variables were numbers of inlets and outlets, distance between floor and lower HP ($h_1$), distance between lower HP and fired materials ($h_2$), distance between fired materials and upper HP ($h_3$), temperature of HP, numbers of HP and distance between HP. The numbers of inlets and outlets were determined so that nitrogen gas formed a laminar flow for efficient discharge. All other design variables were determined so that temperature of fired materials is as uniform as possible near $1,300^{\circ}C$. Chambers were produced and temperature was measured at 21 points using thermocouples. The largest deviation from $1,300^{\circ}C$ was less than ${\pm}2.2^{\circ}C$.

Physico-mechanical Properties and Optimum Manufacturing Conditions of Bi-Sn Metal Alloy Impregnated Wood Composites (Bi-Sn 용융합금주입 목재복합체의 최적제조조건 및 물리·기계적 특성)

  • Park, Kye-Shin;Lee, Hwa-Hyoung;Kang, Seog Goo
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.6
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    • pp.691-699
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    • 2014
  • In order to improve the dimensional stability and durability of wood, this study attempted to impregnate bismuth (Bi) - tin (Sn) alloy metal with low melting temperature into solid woods of three species such as radiata pine, red oak and white oak, and investigated to determine an optimum condition of manufacturing the metal alloy-wood composites with natural wood grains. These Bi-Sn alloys were chosen for this study because they were harmless to human and melting at low temperatures. The composites resulted in high dimensional stability and low thickness swelling, and also showed much improved performance such as high bending strength, high hardness, high electric conductivity, and high thermal conductivity as floor materials. A proper impregnating condition of all specimens was determined as 10 minutes of the preliminary vacuum time, and $185^{\circ}C$ of the heating temperature. The proper processing condition for radiata pine wood was 2.5 minutes of the pressuring time at the pressure of $10kgf/cm^2$. For red oak wood, 10 minutes of the pressuring time at the pressure of $30kgf/cm^2$ were the proper condition. The proper manufacture conditions for white oak wood was determined as 10 minutes of the pressuring time at the pressure of $50kgf/cm^2$.

Living Conditions of the Rural Elderly: Clothing, Nutrition, Housing, and Psychological Adjustment (농촌지역 노인의 생활실태 조사연구 -의.식.주생활 및 심리적 적응을 중심으로-)

  • 윤복자
    • Journal of the Korean Home Economics Association
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    • v.28 no.4
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    • pp.65-86
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    • 1990
  • Living conditions of the rural elderly were assessed in terms of clothing behavior, health and nutritional status, housing and envioronmental condition, and psychological adjustment. The subjects were eighty individuals over sixty residing in the rural community of Iksan-kun, Chollabukdo. The interview method using questionnaires, direct measurement, and observation was used for this study. Data were compared with those obtained from a previous study of the elderly residing in an urban area. Clothing behavior showed that the elderly residing in the rural community were more concerned about plain and conservative design of clothes than their urban counterparts. Special protective clothes for cropdusting with agricultural chemicals had not been prepared. The following urgent needs were pointed out: development and supply of agricultural chemical protective clothing and development and education of appropriate washing and clothing care methods. The health status of the elderly was generally good, but poor eating habits were found more frequently in the rural elderly than among the urban dwellers. Several dietary nutrient intakes were insufficient. Contrasting the urban elderly with the rural group, it was found that the urban group lacked sufficient vitamin A and vitamin C and the urban women had insufficient calorie whereas the rural group was deficient in protein, vitamin A, calorie, and fat. A significant relationship was found between dietary nutrient intake and health index, food habit points, self recognized health status, meal satisfaction, and economic status. Urgent needs of the development of a nutrition education program for the elderly were pointed out. Most of elderly residing in the surveyed rural communities were living alone or with their spouse only, therefore only one room was used among the three or four available rooms. Most of the rural elderly were living either in a traditional Korean house built with differing floor levels or in a modified Korean style house. Minimal modernization had been made for kitchen facilities such as sink and gas range or for heating facilities with the briquette boiler. However, sanitary space such as lavatory and bathroom had not been remodeled. A housing welfare program for rural communities should be implemented at the national level. The comparison of psychological characteristics of the rural elderly with their city counterparts revealed that the rural elderly have a more stable psychological status and optimistic attitude than those living in a city. However, it was found that most of the elderly did not have any future plan. Community programs for the elderly including hobbies or leisure activities or education programs to generate close interpersonal relationships with their children should be developed and provided.

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Evaluation of Biological Critical Control Points Using Escherichia coli Genotyping (Escherichia coli Genotype을 이용한 생물학적 Critical Control Point의 적합성 평가)

  • Kim, Hak-Jae;Hahn, Tae-Wook;Juong, Ji-Hun;Bahk, Gyung-Jin;Hong, Chong-Hae
    • Food Science of Animal Resources
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    • v.29 no.6
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    • pp.695-701
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    • 2009
  • This study was performed to evaluate the effectiveness of biological critical control points using the genetic profile of Escherichia coli isolates from pork cutting plants. Samples were collected from carcasses, equipment (knife, table, glove, transport belt, boning and skinning machine), the environment (wall and floor), and meat cuts during the cutting process from two plants. Pulsed-field gel electrophoresis (PFGE) was used to characterize the E. coli isolates. An identical genotype was detected from the carcasses, equipment, environment, and final meat cuts, and showed that the incoming carcasses, which were contaminated during transportation from slaughterhouses, were a major source of E. coli that was spread throughout processing. Also, consistent cross-contamination due to improper cleaning and disinfection procedures was another possibility. As a result, incoming carcasses and cleaning procedures should be considered critical control points in pork cutting plants, since a heating step is not used to inactivate microorganisms. Furthermore, the high rate (59.6%) of E. coli isolation indicates E. coli can be a good indicator in livestock processing plants even though it has genetic diversity.