• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2423-2430
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• 1994

Several factors of the efficient combustion process are shape of combustion chamber, position of spark plug, turbulence flow and so on. the shape of combustion chamber and position of spark plug are constrained to geometrically, and then it could not make a change the shape easily. But the turlence flow in combustion chamber have a great influence on combustion phenomena, and which is much easier to control relatively. And since characteristics of turbulence flow would be very important to the stability of combustion and performances, This study is also essential to future engine-low emission and lean burn engine. This paper shows that the visualization of the turbulence flow of single cylinder engine by using 2way, $45^{\circ}$ inclined and 2 channel hot wire probe through the park plug hole. We also study the characteristics of turbulence flow by means of ensemble averaged mean velocity, turvulence intensity and integral length scale.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.155-160
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• 2001

The low NOx characteristics have been investigated to develop the combustor for micro turbine. The lean premixed combustion technology was applied to reduce the NOx emission. The test was conducted at the condition of high temperature and ambient pressure. The combustion air which has the temperature of $450\sim650K$ were supplied to the combustor through the air preheater. The temperature and emissions of NOx and CO were measured at the exit of combustor, The exit temperature and NOx were increased and CO was decreased with increasing inlet air temperature. The premixing chamber can be operated very lean condition of equivalence ratio around 0.35. The NOx was decreased with decreasing the equivalence ratio. The CO was decreased with decreasing the equivalence ratio, but the CO was increased with decreasing the equivalence ratio below 0.4. But, at the very lean condition of equivalence ratio below 0.35 both NOx and CO were increased because of the flame unstability. The NOx was decreased and CO was increased with increasing inlet air flowrate. This results can be used to determine the size of combustor. Consequently the performance of combustor shows the possibility of the application to the gas turbine system.

• Archives of Reconstructive Microsurgery
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• v.7 no.2
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• pp.129-134
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• 1998

The ability for tissue transfer based on microvascular anastomosis has created a revolution in microsurgical free tissue transplantation. The advantages of cutaneous flaps are that they are soft, durable and provide a good cosmetic reconstruction and muscle flaps have a more vigorous blood supply and a longer, larger vascular pedicle than cutaneous flaps. From June 1992 through May 1997, 68 patients had received reconstructive microsurgery in the lower extremity at Department of Orthopedic Surgery, Chonbuk National University Hospital. The results were as follows. 1. The age distribution was from 15 years of age to 67 and male were 59 cases and female 9 cases. 2. The most common cause was traffic accident(54 cases, 79.4%) and followed chronic osteomyelitis(9 cases, 13.2%), industrial accident(3 cases, 4.4%), burn(1 case, 1.5%) and farm injury(1 case, 1.5%). 3. Latissimus dorsi myocutaneous flap were 25 cases(36.8%), rectus abdominis muscle flap 21 cases(30.9%), gracilis muscle flap 10 cases(14.7%), dorsalis pedis flap 9 cases(13.2%), groin 2(2.9%) and vascularized iliac osteocutaneous flap 1(1.5%). 4. 61 cases(89.7%) of 68 cases were survived and the exposed vital tissues and bones were covered and revealed good cosmetic results.

• Korean Journal of Materials Research
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• v.13 no.12
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• pp.831-838
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• 2003

Anisotropic mesophase carbon fiber(AMCFs) was exposed to isothermal oxidation in air and $CO_2$atmosphere, and burn-off rates have measured by TGA. The microstructure changes of oxidized carbon fibers, were observed by SEM. It was observed that oxidation rate in the air is over 100 times faster than that in $CO_2$atmosphere. The activation energy obtained in air was about 43.4 Kcal/mole in the temperature range of $600∼800^{\circ}C$, and in $CO_2$was about 55.2 Kcal/mole in the temperature range of $950∼1200^{\circ}C$. Therefore, the oxidation reaction in both atmospheres was under chemical reaction regime in the above temperature ranges. It was shown that the oxidation of the AMCFs is initiated at the end of fibers at high temperature($1100^{\circ}C$) with developing the large pores, and the small pores are developed on the fiber surface at low temperature($900^{\circ}C$). In conclusion, the oxidation of the AMCFs is progressed through the imperfection.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.22-28
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• 1999

The injected liquid does not break-up instantly after injection for diesel engine. There is some unbroken portion, which is the liquid core(The length of liquid core is called the break-up length) in the spray. If the liquid core is longer than the depth of the bowl in the small DI diesel engine, the liquid core impinges on the surface of the piston. Once the liquid core impinges on the surface, it cannot ignite or burn rapidly and thus prolongs burning time with a degradation in thermal efficiency. The break-up length of a diesel spray in a compressure vessel was measured by an electric resistance method, A voltage was applied between the nozzle and screen, bar, needle electrode inserted at various axial and radial positions into atomizing sprays. As a result, a current flows not only in the region of liquid core but also through the droplets of the spray. It is found that the break-up length measured with screen electrode is overestimated. The break-up length of the spray is found to be proportional to the square root of the density ratio of fuel and surrounding gas. The break-up length of the spray decreases as the injection pressure and the back pressure increase.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1744-1759
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• 1992

A multidimensional simulation of turbulent flow and combustion with swirl in the cylinder of SI engine is implemented to clarify the effects of swirl. present simulation employs the ICED-ALE numerical technique, the skew-upwind difference scheme, a modified k_.epsilon. turbulence model, a combustion model of Arrhenius type and turbulence-mixing-control type. First, the calculations for swirling flow in an axisymmetric cylinder are carried out. The results are compared with the experimental data to validate the numerical analysis. Second, the calculations for intake, compression and combustion processes in an axisymmetric cylinder are performed. The effects of swirl on turbulent flow and combustion are examined through the parametric study of swirl number 0.0, 0.6, 1.2 and 2.4. As a result, it is numerically shown that the turbulent kinetic energy and the swirl velocity, which are produced during the intake process, affect the combustion process.

• Journal of Korean Society for Quality Management
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• v.34 no.4
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• pp.1-12
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• 2006

The 'KS-QEI' is the quality evaluation model developed both by Korean Standard Association(KSA) and this research team, reflecting the characteristic of KS products' quality and the customers' demand factors. KS-QEI is a general index measuring and announcing KS products' quality excellency through the evaluation of its real user including customers and specialists. This index aimed to evaluate and announce the quality level of KS product annually which was the motivation of products' quality improvement to enterprises and guaranteed the products' reliability to customers. Ultimately, by competing in good faith among domestic enterprises and preparing foundation of continuous research and investment inducement, it was expected to improve the Korean industry's competitive power. This study was intended to develop improved KS-QEI by analysing 2006 research result, to which it had applied ameliorated and enlarged index in 2005. Especially, it established the weight by Analytic Hierarchy Process(AHP), which led to estimate weight mathematically by comparing and evaluating the importance and difficulty by its index. And this paper analyzed the research result by using multi-variate statistical methods.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.31-41
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• 2008

Steven-Johnson syndrome (SJS) and toxic epidermal necrolysis(TEN) are severe mucocutaneous reaction which are most frequently caused by drugs. Although the incidence of SJS and TEN is known to be relatively low, outcomes may be fatal. A systematic approach is required because morbidity rate is currently increasing and oral lesion is frequent. We investigated the clinical features and outcomes of 6 patients diagnosed as SJS and TEN and referred from the department of dermatology, Chonnam National University Hospital for oral care. Ketoconazol, Ofloxacin, Chlorphenesin, Amoxicillin, Pontal, Harnal, and Ciprofloxacin were suspected as the causative drugs. Average treatment period was 3.2 weeks, and two patients were referred to 'burn-patients' hospital. Most of oral lesion were cured be normal tissue, but scares with discoloration were observed. For intraoral management, antibiotic disinfection and steroid application were performed according to systemic treatment principles. Additionally, ingestion of zinc, antioxidants, and vitamin was recommended. The establishment of oral treatment principles is demanded because it has not been yet. Also, through investigation of drug side effect and careful prescription are required.

• Nuclear Engineering and Technology
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• v.37 no.3
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• pp.265-272
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• 2005

Severe accidents in nuclear power plants can cause hydrogen-generating chemical reactions, which create the danger of hydrogen combustion and thus threaten containment integrity. For containment analyses, a three-dimensional mechanistic code, GOTHIC-3D has been applied near source compartments to predict whether or not highly reactive gas mixtures can form during an accident with the hydrogen mitigation system working. To assess the code applicability to hydrogen combustion analysis, this paper presents the numerical calculation results of GOTHIC-3D for various hydrogen combustion experiments, including FLAME, LSVCTF, and SNU-2D. In this study, a technical base for the modeling oflarge- and small-scale facilities was introduced through sensitivity studies on cell size and bum modeling parameters. Use of a turbulent bum option of the eddy dissipation concept enabled scale-free applications. Lowering the bum parameter values for the flame thickness and the bum temperature limit resulted in a larger flame velocity. When applied to hydrogen combustion analysis, this study revealed that the GOTHIC-3D code is generally able to predict the combustion phenomena with its default bum modeling parameters for large-scale facilities. However, the code needs further modifications of its bum modeling parameters to be applied to either small-scale facilities or extremely fast transients.

• The Korean Journal of Pain
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• v.8 no.2
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• pp.324-327
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• 1995

Central serous chorioretinopathy is a relatively benign condition of young to middle-aged men, characterized by serous detachment of central retina as a consequence of focal leakage of fluid from the choriocapillaris through a defect in the retinal pigment epithelium. Approximately 80% of central serous chorioretinopathy undergo spontaneous resolution within 6 months. However 20 to 30% of patients with central serous chorioretinopathy have one or more recurrences and undergo chronic courses. In these cases laser photocoagulation is used to burn the leakage site directly, but there is no evidence that it reduces the chance of permanent loss of visual function and recurrence. We have administered stellate ganglion blocks (SGB) on a 43 year old male patient with central serous chorioretinopathy with multiple recurrences and experienced good results. We therefore recommend SGB as an effective treatment for central serous chorioretinopathy in conjunction with other ophthalmological treatments.