• Journal of Korean Living Environment System
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• v.24 no.1
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• pp.95-106
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• 2017

The purpose of this study was to evaluate comfort functions while wearing firefighters' protective gloves in dry and wet conditions at $70^{\circ}C$ air temperature with radiant heat. Four types of firefighting gloves from Korea, Germany, United States, and Japan were evaluated in both dry and wet conditions by eight male firefighters. Firefighters put their hands and forearms wearing gloves into a hands-radiant chamber that maintained at an air temperature of $70{\pm}2^{\circ}C$ ($T_a$) and globe temperature $106^{\circ}C$ ($T_g$). During the exposure, subjects followed a fixed protocol of manual movements and stopped the exposure when they felt being intolerable. Results showed that completion time was extended by 6 min on average when gloves got wet and 15 min for the Japanese gloves was extended when compared to its dry condition (p<.001); microclimate humidity on the palm at the last stage was greater for wet conditions than dry conditions in the all gloves; and skin temperatures on mid-fingertip, palm, and hand were significantly lower for wet conditions than dry conditions especially for Japanese gloves (p<.001). These results indicate that the exposure time without thermal pain to radiant heat could be extended by wetting gloves during the low radiant heat exposure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.1
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• pp.36-48
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• 1997

In order to establish the ignition system for lean burn, the influence of the number of spark plug, spark times and spark intervals on discharge pattern of spark energy on ignitability and combustion characteristics were evaluated. It showed that, ignitability remarkably increased with the case of multiple spark ignition system than with the case of single spark and the lean limit extended fuel/air equivalence ratio by 0.1, the increase of magnitude and lasting time of capacity component and inductance component was multi spark discharge in a row.

• Journal of the Korean Society of Combustion
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• v.16 no.1
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• pp.52-57
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• 2011

The present study describes the characteristics of combustion and exhaust emissions in compression ignition engines using diesel-gasoline dual fuel. For investigating combustion characteristics, diesel fuel was injected directly in a single-cylinder compression ignition engine with a common-rail injection system and gasoline fuel was injected into a premixed chamber installed in an intake port. In order to investigate exhaust emission characteristics, exhaust gas was measured by emission analyzer and smoke meter. The experimental results showed that cases of diesel-gasoline dual fuel combustion exhibited extended ignition delay and reduced peak combustion pressure compared to those of directly injected diesel fuel cases. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of rate of heat release(ROHR).

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.209-214
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• 2001

Acoustic field in steady-state is characterized by a Helmholtz equation. The transmission characteristics of acoustic wave devices is however influenced by the presence of the mean flow in the medium. The effect of the mean How introduces additional terms in the equation. In the present paper, two approaches are considered. One is that the equation is directly discretized by FEM for one-dimensional and the axisymmetric case. Another is that the equation is first transformed into the standard Helmholtz equation which is solved by BEM. The numerical demonstrations are made for the axisymmetric FEM and the three-dimensional BEM modeling. The numerical examination for a straight circular duct is first considered. The solutions are compared wish the analytical ones. The examination is then extended to the case when the mean How is locally present in a muser with expansion chamber.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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• pp.542-550
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• 1998

A direct contact heat exchanger using particle-suspended gas as a heat transfer medium is analyzed with an extended emphasis on the radiation, i. e., considering the radiation by both gas and particles. While the Runge-Kutta method is used for a numerical analysis of the momentum and energy equations, the finite volume method is utilized to solve the radiative transfer equation. Present study shows a notable effect by the gas radiation in addition to the particle radiation, especially when changing the chamber length as well as the gas and particle mass flow rate. When the gas and particle mass flow rate is raised, the gas temperature in the particle heater still increases as the gas absorption coefficient increases, which is different from the results for the small scale heat exchanger.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3676-3685
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• 1996

Enhancement of the ignitability was necessary to realize the lean burn engine. The characteristics of multiple-spark capacitor discharge igniter(MSCDI) usefulness of which for lean burn was examined in constant volume combustion chamber and evaluated in spark ignition engine. Noise of MSCDI for engine was restricted by adoption of low voltage control system. It was found that the adaptability for high engine speed was remarkable. Lean limit in engine with MSCDI was extended 10% than conventional coil ignition system. Also maximum brake thermal efficiency was almost enhanced 1%.

• Radiation Oncology Journal
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• v.7 no.2
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• pp.287-291
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• 1989

Radiation dosimetry has been extended to small fields less than $4\times4cm^2$ which may be suitable for irradiation of small intracranial tumors. Special consideration was given to the percentage depth dose and scatter correction factors with 0.14ml ion chamber, film dosimetry and TLD measurement. Calculated dose distributions were compared with measured data.

• Journal of Veterinary Clinics
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• v.35 no.5
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• pp.233-236
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• 2018

A 13-year-old spayed female Beagle dog was referred with high intraocular pressure, hyperemia, and exophthalmos of the left eye and underwent ultrasound, which revealed a mass in the ciliary body of the left eye. Magnetic resonance (MR) imaging was ordered to evaluate invasion of surrounding structures and metastasis to the brain via the optic nerve. On MR imaging, a single, well-defined, smoothly marginated, triangular-to-oval-shaped mass was found. The mass was hyperintense on T1-weighted images and hypointense on T2-weighted images, similar to a previous case of ocular melanoma. The mass originated from the ciliary body and extended from the anterior chamber to the posterior chamber. Slight enhancement was observed in the mass. There was no evidence of invasion into surrounding structures or the optic nerve, and no sign of metastasis to the brain. The mass was histopathologically diagnosed as benign uveal melanocytoma.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.256-259
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• 2008

Ejector system is a device to transport a low-pressure secondary flow by using a high-pressure primary flow. Ejector system is, in general, composed of a primary nozzle, a mixing section, a casing part for suction of secondary flow and a diffuser. It can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejector system is simple in construction and has no moving parts, so it can not only compress and transport a massive capacity of fluid without trouble, but also has little need for maintenance. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an applicable model and operating conditions for an ejector in the condition of sonic and subsonic, which can be extended to the hydrogen fuel cell vehicle. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Optimization technique and numerical simulation was adopted for an optimal geometry design and satisfying the required performance at design point of ejector for hydrogen recirculation. Also, some ejectors with a various of nozzle throat and mixing chamber diameter were manufactured precisely and tested for the comparison with the calculation results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.244-248
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• 2001

According to the progress of the electronic industry and radio communication technologies, mankind might enjoy its abundant life. On the other hand, many social problems such as EMI, and unnecessary electromagnetic wave occur due to the increased use of electromagnetic wave. Therefore, the organizations such as CISPR, FCC, ANSI, etc. have provided the standard of electromagnetic wave environment for the countermeasure of the EMC. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMI/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band from 1 GHz to 18 GHz additionally in the bandwidth of EMI measurement[1]. In this paper, we proposed a new type absorber satisfying the above requirements and carried out broadband design using the equivalent material constants method. Futhermore, the experiments were carried out over the frequency band from 30 MHz to 2 GHz, and hence, the validity of the proposed design theory was confirmed.