• Food Science and Preservation
• /
• v.11 no.4
• /
• pp.448-454
• /
• 2004

This study was conducted to analyze the cooling and the quality characteristics of milled rice stored in the forced air-blast type using thermo -electric semiconductor and in the still-air type chambers using refrigeration system with refrigerant(R-22). Cooling rates of milled rice in the forced air-blast type and in the still-air type chambers were $0.30\;^{\circ}C/hour$ and $0.21\;^{\circ}C/hour$, respectively. And the temperatures of cooling air and of milled rice at different positions in the forced air-blast type chamber showed severer change than those in the still-air type chamber. During storage of milled rice in the forced air-blast type and still-air type chambers for 14 weeks, there was no significant difference in the quality characteristics, such as b value and fat acidity of milled rice, and overall sensory quality of cooked rice. But the quality characteristics of milled rice stored in room temperature chamber($25^{\circ}C$) as control decreased very rapidly compare to those stored in the cooling chambers. In aspect of fat acidity of milled rice, 6 weeks was the limitation for the safe storage in room temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.1
• /
• pp.91-100
• /
• 2004

Energy efficiency evaluation method for a multi-type air conditioning system still has not been developed. In this study, analysis on capacity range and evaluating method of standards for air conditioners was conducted with world-wide Standards. It is not a proper approach to use the standards for residential air conditioner to multi type air conditioners. Some difficulties and problems are commented in this study with overview of the standards. Through the analytic research, an evaluating method for multi type air conditioner was suggested with Integrated Part Load Value (IPLV). The suggested concept for evaluating energy efficiency during part load condition considers building load pattern and operating hours of the system at different locations. Load was weighted in IPLV to consider not only the concept of occurrence of outdoor temperature such as bin method but also operation hours of the system. An experiment about the IPLV was conducted with variable air volume ducted type air conditioning system and multi-type system through modified code tester to give a glance at quantitative value of the IPLV.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.2
• /
• pp.114-117
• /
• 2005

Air cleaners in all of the automotive engines have been used for decades. In the early 1920's the oil bath type was the popular shape of air cleaners. The air cleaners of the oil wetted bath type were introduced in 1940's. The shape of the dry pleated paper type media was introduced in the 1950's. This trend still continues with new and innovative media being introduced. Engine air cleaners should have effectively removed and reduced harmful contaminants being ingested into engines. This studies show that both, the ingested contaminant size and concentration need to be controlled. This paper com pare and analyze the characteristics over the economics, engine performances and reduction of noises of power-plus air filters with wet paper which were sticked to heavy duty diesel engine.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.468-468
• /
• 1991

The variable-frequency type water supply equipment, which adopts the variable-voltage and variable-frequency converter(VVVF converter) to govern automatically the rotating speed of a pump, can save 15-20% of power, as compared with a throttle-controlled pump device or an airpressurized water supply equipment, and is finding a wide application. However, it still has some disadvantages : greater pressure fluctuations during switching over the pump and prolonged low-effeciency running of the pump in the case of small consumption of water. Therefore, it is difficult to apply the equipment to the fire water supply system where the water should not be put into use unless a fire takes place, and the water pressure in pipelines should permanently remain constant. This paper introduces the automatic regulation principle of the variable-frequency type air-pressurized water supply equipment (hereafter referred to as simply BFQS equipment) for dual purposes of daily life and fire control, which combined both technologies of speed governing by a converter and air-pressurized water supplying, then discusses some problems related to automatic control, and finally gives the experimental results of an embodiment-BPQS-100-50 water supply equipment.

• Journal of Advanced Marine Engineering and Technology
• /
• v.25 no.3
• /
• pp.573-580
• /
• 2001

When investigating optimum design of the evaporator in the refrigeration and heat pump systems, there is still lack of data for the dynamic characteristics of the evaporator, This is due to the fact that the static characteristics in the evaporator are absolutely difficult to measure and are burdened with uncertainties. In this study, the simulation works for static characteristics in the evaporator of small air conditioner are carried out to obtain the data of dynamic characteristics. In the simulation, the test evaporator is divided by two-phase evaporating region and single-phase heating region. The major parameters are refrigerant flow rate, heat transfer coefficient of air, air velocity and air temperature. The results show that the calculation method for tube length is an easy-to-use to model analysis of static characteristics and to determine state of refrigerant in the evaporator. The effects of the four parameters on the length of evaporating completed point and heat flow rate to the evaporator are clarified.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.4
• /
• pp.287-293
• /
• 2008

The purpose of this study was to clarify the effects of air and ceiling temperatures on a type of ceiling cooling system that involves cool water circulation. The experiment is conducted in summer. The subjects (11 young females) are exposed to the following conditions: combinations of air temperatures $(27^{\circ}C,\;29^{\circ}C,\;31^{\circ}C)$ and ceiling temperature of $(22.7^{\circ}C,\;23.7^{\circ}C,\;24.7^{\circ}C)$ in still air and RH 50%. The following results were obtained; the thermal sensation vote is neutral at a mean skin temperature of $34.5^{\circ}C$. The ceiling temperature affected different parts of the body. For example, the forehead, scapula and abdomen produced different skin temperatures. Thermal comfort vote was rated as comfortable at high temperature environment. The satisfaction from the ceiling temperature was valued comfortable zone in this experiment. Mean skin temperature showing higher thermal neutrality temperature than existing studies for floor and wall radiation cooling results.

• Journal of Power System Engineering
• /
• v.13 no.3
• /
• pp.11-19
• /
• 2009

This paper introduces a conceptual design of a combined scroll expander-compressor unit for a fuel cell. Since air discharged out of the fuel cell stack has still high pressure energy, some power can be extracted from the air by directing it to pass through an expanding device. Such extracted power can be used to drive an auxiliary compressor. For this purpose, a scroll type expander coupled to a scroll type compressor was designed for a 1kW-class fuel cell. The orbiting scroll members of the expander and the compressor were made to share three of common drive shafts installed in the mid frame plate. Performance analysis for the combined expander-compressor unit showed that the installation of this unit could reduce the auxiliary power consumption in the fuel cell by about 42%.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.3 no.3
• /
• pp.199-208
• /
• 1974

The effectiveness with which evaporative cooling can be used in Korea was analysed by making use of weather data of 15cities in a past decade. In ASHRAE comfort chart for a still air atmospheric condition was divided into two dimensional array, 14 zones by effective temperature and 10 zones by relative humidity, and all hours of weather condition in those zones were. computed from every 4 hours weather data in a past decade. From this computation obtained were for 15 cities : 1. average annual total hours above $23^{\circ}C$ ET 2. effective temperatures with $5\%$ excess factor, and 3. ratios of all hours in wet (above $25.6^{\circ}C$ WBT), intermediate $(22^{\circ}C\;to\;25.6^{\circ}C\;WBT)$, and dry $(below\;22^{\circ}C\;WBT)$ area to total hours in whole area on comfort chart beyond $23^{\circ}C$ ET to effective temperature of $5\%$ excess factor. It was shown from this computational result that in Korea evaporative cooling was not effective for building and residential comfort air conditioning but could be useful for comfort air conditioning in industry and industrial air conditioning, depending upon the air stream velocity and the type of application.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.672-675
• /
• 2006

It is becoming more significant to develop a rotary VCM type actuator for small form factor ODD, as portables are getting more and more popularized nowadays. In this paper, the procedure of development of the actuator which is applicable to compact flash II card and is fit in the specification of BD 1X is explained. This is based on the rotary VCM type actuator, which is good for reducing thickness. Air core solenoid coil is used in order to do focusing mechanism. And the total weight is reduced by using the structure of steel-aluminium-steel triple layer, so, the stiffness is still adequate. Additionally, the tracking coil is moved next to the actuator, so the total length was reduced, then the actuator become applicable to compact flash II card. The force of Magnetic Circuit is improved by using Magnetic Circuit DOE. And flexible mode frequency improved through the DOE of structure part. Modeling was exactly done in consideration of air core solenoid coil and pivot bearing. It is confirmed that the designed model is satisfied with the specification of BD 1X and is applicable to Compact Flash II card.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.29-34
• /
• 2006

Although the importance of good conservation of historic sites including ancient royal tombs is well aware, still not much attention has been paid for the facilities and systems to preserve those historic sites, which includes precious artifacts as wall paints and carved works, etc. Even the level of general understanding about the environment of the underground space of tombs is not satisfactory. In Korea, researchers have recently begun addressing the importance of maintaining proper environment for underground space as of ancient tombs and are making efforts to develop suitable HVAC(heating, ventilating and air-conditioning) systems for them. In this study, an HVAC system for a tomb ($D{\times}W{\times}H=1.3m{\times}3.0m{\times}1.2m$) was installed to maintain suitable indoor conditions for conservation of tomb. The temperature and humidity inside the tomb were measured to represent the performance of the installed duct-type HVAC system. Vibration levels due to the installed an HVAC system are alive investigated experimentally. According to the measured data, the level of vibration inside the present model tomb with the duct-type unit showed significantly lower values than the case with the indoor unit inside.