• Title/Summary/Keyword: Natural draft

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A Study on The Performance of Ventilation and Thermal Environment for a Combined Type Diffuser in a Residential Space (거주공간에 대한 급·배기 일체형 디퓨저의 환기 및 온열환경 유지성능에 대한 연구)

  • Lim, Seok-Young;Chang, Hyun-Jae
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.2
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    • pp.74-81
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    • 2017
  • In this study, the combined-type diffuser developed by the Authors, in a previous study, was applied to a residential space. The performance of a ventilation and thermal environment, created by the use of a combined-type diffuser was compared to the pan-type diffuser widely used in apartment houses. In cooling conditions, because of the relatively high air flow rate of ceiling cassette-type air conditioners, the characteristics of airflow distribution in a room were governed by the air conditioner's airflow. In heating conditions, because of the low air flow rate of the diffuser, the characteristics of airflow distribution were governed by the buoyancy effect created by cold external walls and a hot floor. In terms of the Air Diffusion Performance Index (ADPI), which is a thermal environmental index, the result of a combined-type diffuser was greater than a pan-type diffuser in both of cooling and heating conditions. Consequently, the combined-type diffuser showed equal or superior ventilation and thermal environment performance compared to a pan-type diffuser.

Hydroelastic Analysis for a Very Large Floating Structure by Pressure Distribution Method (압력분포법에 의한 초대형 부유식 해양구조물의 유탄성 해석)

  • H.Y. Lee;H. Shin;H.S. Shin;I.K. Park
    • Journal of the Society of Naval Architects of Korea
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    • v.37 no.4
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    • pp.66-74
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    • 2000
  • In this paper, hydroelastic responses of the very large floating structure are studied based on the linear potential theory. A theoretical method is developed to analyze the hydroelastic reponses of very large floating structures(VLFS) using the pressure distribution method and the modal expansion method. The singularities distributed on a zero draft plate at the free surfaces and hydrodynamic pressures are evaluated. The deflections of structure are expanded approximately in terms of natural mode functions of free-free beam. The calculated items are pressure distributions. vertical motions, hydrodynamic coefficients and bending moments of VLFS. The numerical results are compared with those measured by experiments.

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Investigation of Seakeeping Performance of Trawler by the Influence of the Principal Particulars of Ships in the Bering Sea

  • Thi Thanh Diep Nguyen;Hoang Thien Vu;Aeri Cho;Hyeon Kyu Yoon
    • Journal of Ocean Engineering and Technology
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    • v.38 no.2
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    • pp.43-52
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    • 2024
  • Investigating ship motion under real conditions is vital for evaluating the seakeeping performance, particularly in the design process stage. This study examined the influence of the principal particulars of a trawler on its seakeeping performance. The wave conditions in the Bering Sea are investigated using available data. The length-to-beam (L/B) and beam-to-draft (B/T) ratios of the ship are changed by 10% for the numerical simulation. The response amplitude operator (RAO) motion, root mean square (RMS) value and sensitivity analysis are calculated to evaluate the influence of the trawler dimensions on ship motions. The peak RAO motion affected the ship motions noticeably because of the resonance at the natural frequency. The L/B and B/T ratios are important geometric parameters of a ship that significantly influence its RMS motion, particularly in the case of roll and pitch. The change in the B/T ratio has a good seakeeping performance based on a comparison of the roll and pitch with the seakeeping criteria. The present results provide insights into the seakeeping performance of ships due to the influence of the principal dimensions in the design stage.

How to Reflect Sustainable Development in Overseas Investment including Equator Principles (해외투자(海外投資)와 지속가능발전 원칙 - 적도원칙(赤道原則)(Equator Principles)을 중심으로 -)

  • Park, Whon-Il
    • 한국무역상무학회:학술대회논문집
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    • 2006.06a
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    • pp.45-72
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    • 2006
  • The Equator Principles are a set of voluntary environmental and social guidelines for ethical project finance. These principles commit banks and other signatories to not finance projects that fail to meet these guidelines. The principles were conceived in 2002 on an initiative of the International Finance Corporation and launched in 2003. Since then, dozens of major banks have adopted the Principles, and with these banks among them accounting for more than three quarters of all project loan market volume the Principles have become the de facto standard for all banks and investors on how to deal with potential social and environmental effects of projects to be financed. While regarding the Principles an important initiative, NGOs have criticised the Principles for not producing real changes in financing activities and for allowing projects to go through that should have been screened out by the Principles, such as the Sakhalin-II oil and gas project in Russia. In early 2006, a process of revision of the principles was begun. The Equator Principles state that endorsing banks will only provide loans directly to projects under the following circumstances: - The risk of the project is categorized in accordance with internal guidelines based upon the environmental and social screening criteria of the International Finance Corporation (IFC). - For all medium or high risk projects (Category A and B projects), sponsors complete an Environmental Assessment, the preparation of which must meet certain requirements and satisfactorily address key environmental and social issues. - The Environmental Assessment report addresses baseline environmental and social conditions, requirements under host country laws and regulations, applicable international treaties and agreements, sustainable development and use of renewable natural resources, protection of human health, cultural properties, and biodiversity, including endangered species and sensitive ecosystems, use of dangerous substances, major hazards, occupational health and safety, fire prevention and life safety, socio-economic impacts, land acquisition and land use, involuntary resettlement, impacts on indigenous peoples and communities, cumulative impacts of existing projects, the proposed project, and anticipated future projects, participation of affected parties in the design, review and implementation of the project, consideration of feasible environmentally and socially preferable alternatives, efficient production, delivery and use of energy, pollution prevention and waste minimization, pollution controls (liquid effluents and air emissions) and solid and chemical waste management. - Based on the Environmental Assessment, Equator banks then make agreements with their clients on how they mitigate, monitor and manage those risks through an 'Environmental Management Plan'. Compliance with the plan is required in the covenant. If the borrower doesn't comply with the agreed terms, the bank will take corrective action, which if unsuccessful, could ultimately result in the bank canceling the loan and demanding immediate repayment. - For risky projects, the borrower consults with stakeholders (NGO's and project affected groups) and provides them with information on the risks of the project. - If necessary, an expert is consulted. The Principles only apply to projects over 50 million US dollars, which, according to the Equator Principles website, represent 97% of the total market. In early 2006, the financial institutions behind the Principles launched stakeholder consultations and negotiations aimed at revising the principles. The draft revised principles were met with criticism from NGO stakeholders, who in a joint position paper argued that the draft fails by ignoring the most serious critiques of the principles: a lack of consistent and rigorous implementation.

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A Study on the Classification and Application Element of Outdoor Biotop for Environment-friendly Community (친환경 주거를 위한 외부공간의 비오톱 유형 분류 및 적용 항목에 관한 연구)

  • Cho, Dong-Gil;Cho, Tong-Buhm
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.10 no.1
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    • pp.57-71
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    • 2007
  • While a concept on biotop or the urgency of its classification systems have been under discussion recently, this study aims to examine outdoor biotop classification systems for environment-friendly community. To this end, the feasibility of creating a biotop in the community and application elements were generated and biotops were classified and categorized. Then, elements that can be applied in consideration of traditional Korean techniques were generated and biotop classification systems and specific components in residential areas were reviewed. As for the result of this study, based on a preliminary draft prepared through literature review, considerations for biotop classification systems were taken into account. Then, based on classification criteria for biotop formats, biotop functions and biotop types, a second-tier classification system was developed. Criteria for biotop formats included surfaces, lines and points while criteria for biotop functions were large cores, small bases, corridors, stepping stones and ecological islands. Criteria for habitat types were divided to include natural forest, developed green areas, lacustrine wetland, palustrine wetland, shrubs, grasslands, linear habitats, vacant plots and practical green areas, which were sub-categorized. As for the biotop classification system, macro-classification divided biotops into three types-space, line and point-based on biotop formats. Meso-classification had five groups and micro-classification had 21 groups based on habitat types. Future studies should focus on the ecological features of each biotop categories generated in this study and their creation and management techniques to find many practical methods to create, protect and manage outdoor biotop for environment-friendly community.

A Study on Development of Village Wetlands Inventory Using GIS and Establishment of Management Methods in Asan City, Korea (GIS를 이용한 아산시 마을습지 인벤토리 구축 및 관리 방안 연구)

  • Park, Mi Ok;Yang, Seung Bin;Koo, Bon Hak
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.18 no.6
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    • pp.167-177
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    • 2015
  • This study was conducted to establish an inventory and propose conservation strategies for 'village wetlands' in Asan city, Korea, using GIS. As results, the village wetlands are defined as such places as 'palustrine' wetland, village embankment, agricultural reservoir or small reservoirs located in or near the village and related to everyday life or farming. Firstly 807 provisional village wetlands(draft) were identified in Asan by using Arc-GIS 10.1, then 196 wetlands(final) were defined finally as village wetlands and listed the inventory of Asan Village Wetlands after being validated through office works and field survey. The office works analyzed minimum area(greater than $625m^2$), satellite images, the Korea Land Information System, land use map and land coverage map. To evaluate the function and conservation values, the 37 wetlands were selected for detailed surveying and function assessment based on the following criteria : 1) doubled code both wetland and reservoir at digital map, 2) located less than 100m from village and 3) ecologically connected to such ecological resources as seaside mudflats, mountains and green area and ecological passages for small size wildlifes. As the result of the wetland function assessments by the RAM method, 7 wetlands were found to have 'high' wetland function (conservation) 18 wetlands were 'medium' (enhancement) and 12 wetlands were 'low' (restoration or enhancement). Enhancing biodiversity and ecosystem services through ecological management of wetlands in Asan and connecting with the Ecological Natural Degree were proposed.

Life Risk Assessment of Landslide Disaster Using Spatial Prediction Model (공간 예측 모델을 이용한 산사태 재해의 인명 위험평가)

  • Jang, Dong-Ho;Chung, C.F.
    • Journal of Environmental Impact Assessment
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    • v.15 no.6
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    • pp.373-383
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    • 2006
  • The spatial mapping of risk is very useful data in planning for disaster preparedness. This research presents a methodology for making the landslide life risk map in the Boeun area which had considerable landslide damage following heavy rain in August, 1998. We have developed a three-stage procedure in spatial data analysis not only to estimate the probability of the occurrence of the natural hazardous events but also to evaluate the uncertainty of the estimators of that probability. The three-stage procedure consists of: (i)construction of a hazard prediction map of "future" hazardous events; (ii) validation of prediction results and estimation of the probability of occurrence for each predicted hazard level; and (iii) generation of risk maps with the introduction of human life factors representing assumed or established vulnerability levels by combining the prediction map in the first stage and the estimated probabilities in the second stage with human life data. The significance of the landslide susceptibility map was evaluated by computing a prediction rate curve. It is used that the Bayesian prediction model and the case study results (the landslide susceptibility map and prediction rate curve) can be prepared for prevention of future landslide life risk map. Data from the Bayesian model-based landslide susceptibility map and prediction ratio curves were used together with human rife data to draft future landslide life risk maps. Results reveal that individual pixels had low risks, but the total risk death toll was estimated at 3.14 people. In particular, the dangerous areas involving an estimated 1/100 people were shown to have the highest risk among all research-target areas. Three people were killed in this area when landslides occurred in 1998. Thus, this risk map can deliver factual damage situation prediction to policy decision-makers, and subsequently can be used as useful data in preventing disasters. In particular, drafting of maps on landslide risk in various steps will enable one to forecast the occurrence of disasters.

A Study of Sleeve Cap in the Knitwears with Plain Stitch (Plain 조직 니트 의류의 소매산 형태 연구)

  • Hong Soo-Sook;Suh Mi-A
    • The Research Journal of the Costume Culture
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    • v.14 no.3 s.62
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    • pp.404-417
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    • 2006
  • The purpose of this thesis, therefore, is to examine the shaping methods and the knitting drafts of sleeve cap in the knitwears which are currently used by the manufacturers; to study the curve forms of sleeves in knitwears by analyzing synthetically the results of investigating the problems of knit wear sleeves; to present the most suitable sleeve cap for the knitwears. As the studying methods, I collected the basic data from the working-level persons of knit wear manufacturers, examined the knitting draft in the knitwears, and from that, made three kinds of comparative experimental garments and one kind of research experimental one as 10G and 16G. In doing so, I showed the sleeve cap suitable for the knitwears with plain stitch after operating sensual evaluation with Liker's 5-point rating measure. The analysis of data was handled with statistics by using SPSS Ver. 12.0; the method of statistics was executed by Frequency Analysis, Trust Analysis, one-way ANOVA, and Duncan test according to each topic of the research. As the result of the sensual evaluation of the experimental garments produced from the study, the research experimental garment looks better than the comparative experimental one in both 10G and l6G; has less extra folds around the front part of sleeve cap; looks more natural in sleeve caps of the body part and of a sleeve. From this, I am able to figure out that the research experimental garment looks better than the comparative experimental one produced by knit wear manufacturers. In addition, I can come to know that the different knitting of the front line and the back one of armhole in the knitwears has a favorable impact on improving the appearance of a sleeve.

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Design of Wave Energy Extractor with a Linear Electric Generator -Part I. Design of a Wave Power Buoy (선형발전기가 탑재된 파랑에너지 추출장치 설계 -I. 파력 부이 설계)

  • Kim, Jeong Rok;Bae, Yoon Hyeok;Cho, Il Hyoung
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.17 no.2
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    • pp.146-152
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    • 2014
  • Design procedure of WEC (wave energy converter) using the heaving motion of a floating cylinder-type buoy coupled with LEG (linear electric generator) system is introduced. It is seen that the maximum power can actually be obtained at the optimal conditions ($c_{PTO}=b_T$, ${\omega}={\omega}_N$). Then, based on the developed theory, several design strategies are proposed to further enhance the maximum PTO (power take off), which includes the intentional mismatching with the heave natural frequency, which is 15% higher value than the peak frequency of input velocity spectrum. By using the intentional mismatching strategy, the generated power is actually increased and the corresponding draft as well as the required PTO damping value is significantly reduced, which is a big advantage in manufacturing the WEC with practical LEG (linear electric generator) system.

Genome sequence of Bifidobacterium dentium strain ATCC 15424 originally isolated from pleural fluid of an empyema patient (농흉 환자의 흉막액에서 분리된 Bifidobacterium dentium strain ATCC 15424의 유전체 염기서열 해독)

  • Moon, Ji-Hoi;Kim, Suegene;Yang, Seok Bin;Jang, Eun-Young;Shin, Seung-Yun;Lee, Jin-Yong;Lee, Jae-Hyung
    • Korean Journal of Microbiology
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    • v.55 no.3
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    • pp.280-282
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    • 2019
  • We present here a draft genome sequence of Bifidobacterium dentium strain ATCC 15424, originally isolated from pleural fluid of an empyema patient. The genome is 2,625,535 bp in length and has a GC content of 58.5%. The genome includes 2,154 protein-coding genes, 4 rRNAs, and 55 tRNAs. Unlike other B. dentium strains isolated from human dental caries, ATCC 15424 carries 247 strain-specific genes, including prophage remnants and type III/IV secretion system proteins, N-acetylmuramoyl-L-alanine amidase, and PRTRC system protein E. The sequence information will contribute to understanding of the natural variation of B. dentium as well as the genome diversity within the bacterial species.