• Title/Summary/Keyword: Air change rates

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Unlimited Liability

  • Mckay, John S.
    • The Korean Journal of Air & Space Law and Policy
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    • v.6
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    • pp.137-147
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    • 1994
  • Clearly there are many legal arguments and criticisms surrounding the proposals for change in the Warsaw Convention and the need for a radical review. The question remains is unlimited liability the answer or should there be some other form of supplemental compensation and if so, what limits should be applicable. It does seem that the adopted limits of the Convention are seen by many as the first line of defence, which, dependent on political and cultural differences, the legal interpretation of contractual wording and the legal system globally have resulted in enormous differences in compensation paid whether or not the Convention limits were imposed. An example of this is in the United States, which highlights the significance of the problem in that domestic travellers without Convention Limits can, through the American legal system, obtain compensation in the multi-million dollar area for a death claim, whereas a passenger t1ying internationally would in the first instance be subject to Convention Limits. expensive legal action through litigation. To date, we can advise that insurers have not charged additional premium for unlimited liability coverage. Insurance rates as we have stated are hardening considerably. To date, average rate increases have been plus 56% for aircraft hull and plus 45% for liabilities. Insurers last year suffered global losses of around US $ 1.1 Billion against a premium income of US $ 800,000. The target premium income for 1993 is believed to be in the region of US $1.4 Billion.

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An Investigation into Improving the Quality of Modern Weapon System Software Products: a Case Study (현대 무기체계 소프트웨어 개발 사례 분석을 통한 품질개선 방안에 대한 연구)

  • Choi, Taeyun Paul;Lee, Hyo-Jin
    • Journal of the Korean Society of Systems Engineering
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    • v.8 no.2
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    • pp.19-25
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    • 2012
  • As modern weapon systems have evolved into embedded software systems, the capability to develop, install, and maintain high-quality software products is becoming increasingly valuable in today's competitive aerospace and defense industry. It is desirable, especially for government-contracted projects whose end-users are military personnel, that specific types of software quality elements are assured early during product development; namely, functionality and usability. Motivated by this need to approach improving software quality from a user's perspective, this paper presents a case study that analyzes system-level software integration testing results for a weapon system indigenously developed in the Republic of Korea. Quantitative data, such as software defect ratios and configuration change rates, are computed to observe meaningful trends with respect to functionality - represented by tests designed to verify the system's electrical signal interfaces - and usability, which is evaluated in terms of how often the initial human-computer interface had to be re-designed. Insights gained from these exercises are subsequently presented as a set of "lessons learned" to take into account when developing new software items for complex weapon systems.

A Numerical Study on the Performance Characteristics of a Piezoelectric Micropump for Different Inlet and Outlet Positions (${\cdot}$출구 위치 변화에 따른 압전 구동방식 마이크로 펌프의 성능특성에 관한 수치해석적 연구)

  • Kim Dong Hee;Jeong Jin;Kim Chang Nyung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.1
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    • pp.33-38
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    • 2005
  • This study has been conducted to investigate flow characteristics of a micropump with piezoelectric materials. In this study, the change of flow rates has been investigated for different positions of the inlet and outlet and for different distances between them. The FSI(Fluid Structure Interaction) method has been employed for numerical analysis of the piezoelectric diffuser/nozzle based micropump. It has been found that time averaged flow rate is greater in the case that distance between the inlet and outlet is longer. For the cases where the positions of the inlet are different with the position of the fixed outlet at the center, the flow rate is increased as the inlet is located farther from the center. This study may supply fundamental understandings for the design and analysis of the prototypes of piezoelectric micropumps.

A Study on the Pollutant Reduction by Venturi Type After-burner (벤츄리형 후연소기의 오염물질 저감에 관한 연구)

  • Lee, Hwa-Sin;Lee, Yong-Hoo;Lee, Jin-Seok;Kwon, Oh-Boong;Lee, Do-Hyung
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.06a
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    • pp.81-86
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    • 2005
  • The purpose of this study is to develop venturi type after-burner in order to obtain pollutant reduction effect and find the best stable combustion condition. For this purpose, through a flow analysis, the shape of venturi type was made and flame holder locations were also decided by measuring chemical species at before and after the after-burner. Also, various chemical species concentration were measured at changing the induced air rates and the oxygen for oxygen enrichment for the solution the problems of much oxygen flow rate and the flame stability range. As results of this study, a flow distribution and the purification effect was excellent at venturi contraction 0.5 and flame holder location 12mm below the center of Venturi throat. On the purification characteristics, we found that pollutants reduction was effective when area ratio and oxygen are increased. But there are suitable quantities due to the flame shape change and combustion efficiency.

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Effect of Wavy Flow of Vertical Falling Film on the Absorption Performance (흡수성능에 미치는 수직 액막 파동의 영향에 관한 연구)

  • 김정국;조금남
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.2
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    • pp.194-201
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    • 2004
  • In the present study, the improvement of absorption characteristics on combined heat and mass transfer process in a falling film of a vertical absorber by change of geometric parameters were studied experimentally and analytically. The energy and diffusion equations are solved simultaneously to give the temperature and concentration variations at the liquid solution-refrigerant vapor interface and at the wall. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by refrigerant vapor in the absorber. Effects of film Reynolds number, geometric parameters by insert device (spring) and flow pattern on heat and mass transfer performances have been also investigated. Especially, effects of the flow pattern by geometric parameters have been considered to observe the total heat and mass transfer rates through falling film along the absorber. As a numerical and experimental result, maximum absorption rate was shown at the wave-flow by insert device (spring). The error ranges between experiment and analysis were from 5.8 to 12% at Re$_{f}$ > 100.0.

Power Maximization of a Heat Engine Between the Heat Source and Sink with Finite Heat Capacity Rates (유한한 열용량의 열원 및 열침 조건에서 열기관의 출력 극대화)

  • Baik, Young-Jin;Kim, Min-Sung;Chang, Ki-Chang;Lee, Young-Soo;Ra, Ho-Sang
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.8
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    • pp.556-561
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    • 2011
  • In this study, the theoretical maximum power of a heat engine was investigated by sequential Carnot cycle model, for a low-grade heat source of about $100^{\circ}C$. In contrast to conventional approaches, the pattern search algorithm was employed to optimize the two design variables to maximize power. Variations of the maximum power and the optimum values of design variables were investigated for a wide range of UA(overall heat transfer conductance) change. The results show that maximizing heat source utilization does not always maximize power.

Effect of Artificial Warming on Chlorophyll Contents and Net Photosynthetic Rate of Quercus variabilis Seedlings in an Open-field Experiment (실외 인위적 온난화 처리가 굴참나무 묘목의 엽록소 함량 및 순광합성률에 미치는 영향)

  • Jo, Wooyong;Son, Yowhan;Chung, Haegeun;Noh, Nam Jin;Yoon, Tae Kyung;Han, Saerom;Lee, Sun Jeoung;Lee, Sue Kyoung;Yi, Koong;Jin, Lixia
    • Journal of Korean Society of Forest Science
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    • v.100 no.4
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    • pp.733-737
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    • 2011
  • We investigated the effect of artificial warming on chlorophyll contents and net photosynthetic rates of 2-year-old Quercus variabilis seedlings in a nursery open-field experiment site. 64 seedlings were each planted in $1m{\times}1m$ plots (n = 4) and warmed with infrared lamps. The air temperature in warmed plots was $3^{\circ}C$ higher than that of control plots. Chlorophyll contents and net photosynthetic rates were measured in May, July, August, September and October, 2011. In May, September and October chlorophyll contents and net photosynthetic rates were significantly higher in warmed plots than in control plots. However, there were no significant differences in chlorophyll contents and net photosynthetic rates between warmed plots and control plots in July and August. It seemed that early developed leaves of warmed plots in May with higher chlorophyll contents could lead to higher net photosynthetic rates whereas there was no difference in net photosynthetic rates due to saturation of chlorophyll contents in July and August. Increased biosynthesis of chlorophyll due to warming might increase net photosynthetic rates in September and October.

Removal Characteristics and Mass Balance Analysis of Mixed VOCs in Trickle Bed Air Biofilter Using Backwashing Operation (역세척공정을 이용한 Trickle Bed Air Biofilter의 혼합VOCs 분해특성 및 물질수지 고찰)

  • Kim, Dae-Keun;Sorial, George A.
    • Journal of Korean Society for Atmospheric Environment
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    • v.25 no.6
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    • pp.503-511
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    • 2009
  • VOC mixture was fed to a trickle bed air biofilter (TBAB) with step-change in influent mixture concentrations from 50 ppmv to 1,000 ppmv, corresponding to loadings of $5.7\;g/m^3/hr$ to $114.1\;g/m^3/hr$. VOC mixture was an equimolar ratio of two aromatic VOCs, i.e., toluene and styrene, and two oxygenated VOCs, i.e., methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK). The TBAB system employed backwashing as biomass control. The experimental results showed that a critical loading rate for VOC mixture removal was determined to be about $60\;g/m^3/hr$, and critical loading rates for individual VOCs in the mixture were different. Specifically, toluene content in the mixture played a major role in the biofilter overall performance. As VOC mixture was fed beyond the critical loading rate, reacclimation of the biofilter to reach the 99% removal efficiency following backwashing was delayed, which was a critical factor in the biofilter performance. In the mass balance analysis, 63.8% of the carbon equivalent in VOCs removal was used for $CO_2$ production during the experimental runs. The 82.6% nitrogen utilized in the biofilter was contributed to microbial cell synthesis. The obtained results were compared against consistently high efficient performance of TBAB for VOC mixture by employing backwashing as biomass control.

An Experimental Study On The Effect of Bopaetang on Rats with Exposured to Sulfur Dioxide (보폐탕이 이산화황에 폭로된 흰쥐의 호흡기 손상에 미치는 영향( I ))

  • Soh Kyung-Sun
    • Journal of Society of Preventive Korean Medicine
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    • v.2 no.1
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    • pp.55-65
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    • 1998
  • Surfur dioxide, one of the air pollutants, has been related increasing morbidity rates due to respiratory damages. To investigate the effect of Bopaetang(補肺湯) on rats induced by exposur of $SO_2$, an experimental study was done the changes on white blood cell(W5C), the content of glycoprotein in treachea and the edema, congestion, inflammatory infiltrates of trachea. The experimental groups are the normal group, control group and sample group( administered Bopaetang to rats induced by exposur of $SO_2$). The results were as follows; 1. The change on WBC on rats induced by exposur of $SO_2$ were made significant differences in sample group compared with control group. 2. The content of Glycoprotein In trachea were made significant differences in sample group compared with control group. 3. The edema, congestion, inflammatory infiltrates of treachea were made significant differences in sample group compared with control group.

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Modeling of Combustion and Heat transfer in the Iron Ore Sintering Bed;Evaluation of the Calculation Results for Various Cases (제철 소결기 배드 내 연소 및 열전달 모델링;인자 변화에 의한 계산 결과 평가)

  • Yang, Won;Ryu, Chang-Kook;Choi, Sang-Min
    • 한국연소학회:학술대회논문집
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    • 2002.06a
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    • pp.171-178
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    • 2002
  • Numerical simulations of the condition in the iron ore sintering bed are performed for various parameters. The sintering bed is modelled as an unsteady one-dimensional progress of solid material, containing cokes and iron ore. Bed temperature, solid mass and gas species distributions are predicted for various parameters of moisture contents, cokes contents and air suction rates, along with the various particle diameters of the solid for sensitivity analysis. Calculation results show that influences of these parameters on the bed condition should be carefully evaluated for achievement of the self-sustaining combustion without the high temperature section, which can cause the excessive melting in the bed. It suggests that the model should be extended to consider the bed structural change and multiple solid phase, which can treat the inerts and fuel particles separately.

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