• Journal of Environmental Health Sciences
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• v.43 no.2
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• pp.95-102
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• 2017

Objectives: This study was conducted to evaluate the emission of VOCs from clothing that had been dry cleaned. Methods: In order to ensure the same conditions, f100% wool scarves were selected as the fabric type. Four identical tests were conducted on the option of either removing the plastic bags which came from the dry cleaning shop or not. The scarf was located inside a closet or room for one or two days. Small chamber tests were conducted to determine the VOC emission characteristics under the same conditions such as temperature, humidity, loading factor, and air exchange rates. Air from the chamber for VOCs was sampled by Tenax TA tube and analyzed by thermal desorption and GC/MSD. Results: Assuming that test represented dry cleaning and consumer's conditions well enough, we can conclude that immediate emissions after the dry cleaning of the scarfs caused elevated levels of TVOC, five VOCs (benzene, toluene, ethylbenzene, xylene, stylene), and decane group compounds. Conclusions: By removing the plastic bags which came from the dry cleaning shop or not, the storage conditions of dry cleaned scarfs by consumers during the storage time periods (one to three days) would be significant for reducing VOC emissions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.6
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• pp.242-252
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• 2018

It is well known that an Oscillating Water Column Wave Energy Converter (OWC-WEC) is one of the most efficient wave absorber equipment. This device transforms the vertical motion of water column in the air chamber into the air flow velocity and produces electricity from the driving force of turbine as represented by the Wells turbine. Therefore, in order to obtain high electric energy, it is necessary to amplify the water surface vibration by inducing resonance of the piston mode in the water surface fluctuation in the air chamber. In this study, a new type of OWC-WEC with a seawater channel is used, and the wave deformation by the structure, water surface fluctuation in the air chamber, air outflow velocity from the nozzle and seawater flow velocity in the seawater channel are evaluated by numerical analysis in detail. The numerical analysis model uses open CFD code OLAFLOW model based on multi-phase analysis technique of Navier-Stokes solver. To validate model, numerical results and existing experimental results are compared and discussed. It is revealed within the scope of this study that the air flow velocity at nozzle increases as the Ursell number becomes larger, and the air velocity that flows out from the inside of the air chamber is larger than the velocity of incoming air into the air chamber.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.2
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• pp.58-68
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• 1982

It is well known to diesel engineers that the heat release pattern is one of the most important factors affecting engine performance. Thorough research in heat release pattern has materially helped the progress in high-speed diesel engine development . This paper is based on the research conducted at KAIST and Daewoo Heavy Industry last year. The purpose of this paper is to determine the heat release pattern in combustion chamber of MAN M type, the famous low-noise engine. Thermodynamic cycle simulation was performed using Whitehous-Way's heat release pattern with modified coefficients and Annand's heat transfer model. Instantaneous temperature and pressure of gas in cylinder could be determined by the numerical solution of simultaneous equation of mass conservation, equation of energy conservation, and state equation of ideal gas. Calculated results were compared with measured values in some details emphasizing upon the factors affecting rate of heat release. The agreement was fairly good and revealed why M type should have lower burning velocity at the early part of combustion in spite of high injection rate. Additional results by parametric studies were given in relation to fuel injection conditions for further application to engine development.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.27-38
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• 1994

In this paper, a simplified model of a hydraulic actuator system for a low-band type active suspension system is derived. To reduce the order of model, time constants of each chamber in hydraulic system are neglected except that of an accumulator. And the dynamics of a spool in the pressure control valve is regarded as a first-order system. The step response and the frequency response of the simplified second-order simulation model exhibit a good agreement with those of the actual system as well as those of the tenth-order simulation model. It is possible to simplify the tenth-order model to the second-order one. The low-band type active suspension model is built up by combining of a quarter car model test rig to testify the validity of the simplified model. The experimental results of suspension characteristics show that the simplified second-order hydraulic actuator model is reasonable to describe the dynamics of the actual hydraulic actuator system for a low-band type active suspension system.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.24-29
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• 2003

Deep sea water has cold temperature, abundant nutrients and minerals, and good water quality that is pathogen-free and stable. Compared with surface water, deep sea water contains more nutrition salt, such as nitrogen and phosphor. Moreover, if has the good balance of minerals. Because of the ability of the spray drying process to produce a free-flowing power considering of spherical particles with a well-defined size distribution and the rapid drying times for heat-sensitive material, spray drying is attractive for a wide range of applications spray drying is a unique unit operation in which powders are produced from a liquid feed in a single processing step. Key component of the process are atomizer, spray chamber. Design of spray chamber should be based on the atomizer type, the production rate, and the particle size required. Because of the complex processes taking place during spray drying, traditional design method are based on pilot-plant tests and empirical scale-up rules. Modern technique such as CFD have a role to play in design and troubleshooting.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.11
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• pp.1486-1496
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• 2000

The initial flame kernel development and flame propagation in a constant volume combustion chamber is analyzed by the heat release rate and the mass fraction burnt. The combustion pressure is measured with a piezoelectric type pressure sensor. In order to evaluate the effects of ignition system and ignition energy on the flame propagation, four different ignition systems are designed and tested, and the ignition energy is varied by the dwell time. Several different spark plugs are also tested and examined to analysis the effects of electrodes on flame kernel development. The results show that the when the dwell time is increased, and when the spark plug gap is extended, heat release rate and the mass burnt fraction are increased. The materials and shapes of electrodes affect the flame development, because they change the energy transfer efficiency from electrical energy to chemical energy. The diameter of electrodes influences not only the heat release rate but also the mass burnt fraction as well.

• Journal of the Korea Furniture Society
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• v.22 no.1
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• pp.13-17
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• 2011

Recently, interest in indoor air quality is increasing. Especially, radon radioactivity among the indoor air is a well-known risk factor for lung cancer because of ionizing radiation in the form of ${\alpha}$-particles. This study was carried out to investigate effect of black charcoal and activated carbon for reduction of radon radiation that emitted from building materials. Black charcoal and activated carbon were used as a barrier which was against the infiltration of radon. The source of radon was gypsum board. Two types of charcoal barrier were powder- and board-type with 5 mm, 10 mm thickness respectively. The method for this determination is evaluated radon concentration in chamber. The measurements were performed with radon detector, SARAD3120. Results of this study are as following: Black charcoal and activated carbon confirmed the highly efficient barrier. Radon concentration was reduced from 72% to 85% as compared the control chamber. Radon reduction capability, however, was no difference as barrier's types. Results obtained in ventilation condition, radon concentration shows 5.93 pCi/L on average in the closed condition and shows 2.69 pCi/L in the opened condition.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.77-84
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• 2006

With the development of micro/nano spacecraft, concepts of micro propulsion are introduced for orbit transfer and drag compensation as well as attitude control. Micro solid propellant thruster has been attention as one of possible solution for micro thruster. In this paper, micro solid propellant thruster is introduced and research on basic components of a micro solid propellant thruster is reported. Micro Pt igniter was fabricated through negative patterning and quantitative effect of geometry was estimated. The characteristic of HTPB/AP solid propellant was investigated to measure the homing velocity. A combustion chamber was fabricated by means of anisotropic etching of photosensitive glass. Finally, micro solid propellant thrusters having various geometries were fabricated and tested.

• Journal of Ocean Engineering and Technology
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• v.36 no.1
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• pp.21-31
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• 2022

In recent years, various studies have been conducted on oscillating-water-column-type wave energy converters (OWC-WECs) with multiple chambers with the objective of efficiently utilizing the limited space of offshore/onshore structures. In this study, a numerical investigation based on a numerical wave tank was conducted on single, dual, and triple OWC chambers to examine the hydrodynamic performances and the energy conversion characteristics of the multiple water columns. The boundary value problem with the Laplace equation was solved by using a numerical wave tank based on a finite element method. The validity of the current numerical method was confirmed by comparing it with the measured data in the previous experimental research. We undertook a series of numerical simulations and observed that the water column motion of sloshing mode in a single chamber can be changed into the piston motion of different phases in multiple OWC chambers. Therefore, the piston motion in the multiple chambers can generate considerable airflow at a specific resonant frequency. In addition, the division of the OWC chamber results in a reduction of the time-dependent variability of the final output power from the device. As a result, the application of the multiple chambers leads to an increase of the energy conversion performance as well as a decrease of the variability of the wave energy converter.

• Journal of radiological science and technology
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• v.30 no.2
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• pp.147-151
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• 2007

AAPM TG43 report has recommended to measure air kerma strength with the strength of source. Main purpose of this study is to verify the accuracy of air kerma strength provided by manufacturer. Materials for this study were MAX-4001 Electrometer, HDR 1000 Plus of the corporation of standard imaging, and 6 french bronchial Applicator with 1000 mm. we measured ionization current in 10-90 mm range from the bottom of the central axis of chamber. The reference point of calibration displayed by the maximum ionization current in the ionization current curve was measured, and air kerma strength was computed from the maximum ionization current. we acquired 50 mm distance to correspond with the maximum ionization current in the ionization current curve. Its distance has perfectly fitted to the source reference point of calibration certificate of UW-ADCL. Air kerma strength computed value has measured about 0.5% more than calibration value provided by manufacturer. Air kerma strength of calibration certificate provided by manufacturer has acquired reliable results. This study shows that considering the move error of dwell position of source and the dead space length in well-type chamber is a good way to get an accurate result.