• Journal of the Korean Solar Energy Society
• /
• v.22 no.3
• /
• pp.1-10
• /
• 2002

Relatively being economical in installation and easy in operation, hot-air heating system has been generally used in greenhouse for heating system regardless of high cost in maintenance and uneven distribution of air temperature. Therefore to overcome the disadvantages in maintenance and in distribution of air temperature and to improve efficiency of heating system, this experimental study is performed. This experimental study aims to improve the character of uneven temperature distribution in vertical direction and to reduce energy consumption for heating in a greenhouse. The experiment had been performed to investigate change of thermal environment and effects on reducing energy consumption for heating in greenhouse by additional surface insulation and reduction of indoor-air volume that come by installing transparent vinyl membranes with different height in each house. The results show that there is a wide difference in oil-energy consumption between houses according to condition of surface insulation and change of indoor-air volume. Furthermore, the results show that the efficiency of dual surface is higher than that of change of indoor-air volume in terms of energy saving.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.19 no.2
• /
• pp.37-44
• /
• 2011

This paper summarizes the HVO concept and procedures, presents a summary of the research and results, and outlines areas where future HVO is required. This concept enables people to get their destinations through shortest paths with advanced air traffic control system and equipments. The concept's key feature is that pilots maintain their own separation from other aircraft using air-to-air datalink and on-board software which are needed for supporting flight information present on the high Way in the sky display and airborne internet. By assigning Self-Controlled Area which assume pilot have separation responsibility, controllers evaluated SATS HVO concept as a successful method on the view of reduced workload and increased traffic level on high volume operation.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.4
• /
• pp.201-209
• /
• 1996

This study describes the combustion characteristics of methance-air mixture with various equivalence retio and initial conditions of mixture in constant volume combustion chamber. Combustion characteristics of methane-air mixture such as combustion pressure, combustion temperature, and heat release were investigated by the measurement of combustion pressure and temperature in the combustion chamber. The results show that maximum combustion pressure, gas temperature and rate of heat release have peaks at equivalence ratio of 1.1. Combustion duration is also the shortest at the equivalence ratio of 1.1 and it is shortened as initial mixture temperature increases.

• Journal of Environmental Health Sciences
• /
• v.19 no.4
• /
• pp.1-9
• /
• 1993

Since most people spend a large majority of their time indoors (at least in the industrialized countries), indoor air may affect human health more than outdoor air. This study was carried out to characterize the reference and equivalent methods against the low volume method which was promulgated by the Ministry of Health and Social Affairs. The Laser and Piezo air sampler offer the advantage of real time data and low labor costs. The arithmetic mean concentrations were found to be 102.9% (Laser-2 min method) and 65.9% (Piezo method) against low volume method (100%). The statistical analysis procedure for this comparision is linear regression. The linear regression line of low volume method had slopes of 0.5487 and 0.9697 and Y intercepts of 0.0266 and 0.0110 $\mu$g/m$^3$ about Laser (2 min) and (24 h) method respectively. And the correlation coefficients were 0.7271 and 0.9433.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.4
• /
• pp.29-36
• /
• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of inhomogeneous charge methane-air mixture under several parameters. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer was used to investigate the effect of initial charge pressure, excess air ratio and ignition times on combustion pressure and combustion duration. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to beneath 0.05m/s gradually at 3 seconds. Second mixture is accompanied by an increase in the combustion rate, and that the higher the mass which is added in the second stage injection, the faster the burn rate.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.11
• /
• pp.125-131
• /
• 1995

Pneumatic System has been mainly used as main equipment for actuation and control of fluid force in manufacturing industry. For velocity control of piston, meter-out restriction method is used in many cases. In this systems, meter-out restriction method is adopted for analysing the Dynamic Charging and Discharging Process which is Variable Volume Chamber. Experiments has been conducted for different supply pressure condition. As a experimental result, charge side chamber pressure rises to supply pressure rapidily and discharge side chamber pressure decreases. Also, when the air in the cylinder is discharged, tempdrature of air decreases steeply. Restriction of the Cylinder sometimes freeze and it dose not function. The result will be useful for the analysis of pneumatic system.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.18 no.5
• /
• pp.463-481
• /
• 1989

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.18 no.6
• /
• pp.498-506
• /
• 1989

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.18 no.4
• /
• pp.303-318
• /
• 1989

• Architectural research
• /
• v.1 no.1
• /
• pp.47-53
• /
• 1999

An interesting of desktop air-conditioning system is the Personal Environmental Module(PEM) System. The PEM system allows the occupant to choose the desired temperature, air volume and direction of the discharged air. In this study, the measurements on the age of air and the air change effectiveness, using the tracer gas method, are carried out to analyze the ventilation performance for provision of fresh air near the breathing zone by the PEM. The relations between the PEM for optimal control and other factors related to indoor air quality, and the ventilation for the PEM are examined. Also, three different supply diffuser types(desktop, floor and ceiling) are compared in view of their ability to distribute supply air to the workstation breathing zone. The desktop diffuser type could deliver air directly to the occupants breathing zone with a high degree of effectiveness. The minimum local age of air was measured in the breathing zone, which is directly supplied with air from the PEM diffusers, and the measured local air change effectiveness of the desktop diffuser in the breathing zone was about 1.13 to 1.23 times greater than that of the ceiling and floor diffusers. When the minimum outside air change rate as specified using ASHRAE Standard 62R is supplied with a desktop diffuser type, the volume of outside air can be reduced 13 to 23%, resulting in a commensurate in ventilation energy use.