• Journal of the Korean Society of Systems Engineering
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• v.12 no.2
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• pp.29-38
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• 2016

The threats around Korea Peninsula have been dramatically increased because North Korea is developing the Nuclear ballistic missile, Submarine launched ballistic missile(SLBM), and many kinds of weapons for sudden provocations. Therefore, ROK navy needs the cutting-edge warship combat systems in order to defeat the enemy threats effectively in the sea. The paper analyzes current warship combat system acquisition process and studies US navy and other advanced countries acquisition process and their contraction trends. After that, the paper proposes the optimal acquisition process of warship combat system for the ROK navy based on our current situation and other advanced countries acquisition trends. The paper will dedicate the next generation warship combat system acquisition process.

• The Journal of Korean Medicine
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• v.21 no.1
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• pp.109-113
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• 2000

A hiccup is an involuntary, spasmodic contraction of the diaphragm accompanied by a sudden closure of the glottis, which is reported commonly in patients with brain stem disease such as ischemic stroke, dolichoectatic basilar artery, tumor, encephalitis, and multiple sclerosis. 1) Intractable hiccup is an uncommon, chronic and incapacitating disturbance defined as a hiccup bout lasting more than 48hours or recurring despite various treatments and affecting male subjects more than female. 2) Constipation and hiccup are common symptoms in stroke patients and purgation therapy has been often used. We discovered two patients who had a hiccup symptom after purgation therapy(diarrhea) and so reported course and result of treatment.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.1
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• pp.1-8
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• 2002

A numerical analysis was performed on the fluid flow in injector orifice of a liquid rocket engine. The present computational code was verified against the published data for turbulent flow in a pipe with a sudden expansion-contraction. Considered were the parameters for the flow analysis in an injector orifice: Reynolds number, ratio of mass flow rate of the injector orifice and inlet flow rate, and slant angle of the injector orifice. The discharge coefficient increased slightly as the Reynolds number increased. The slant angle of the injector changed critically the discharge coefficient. The discharge coefficient increased by 7% when the slant angle changed from $-30^{\circ}$ to $30^{\circ}$ The ratio of mass flow rate had relatively little impact on the discharge coefficient.

• Clinics in Shoulder and Elbow
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• v.22 no.2
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• pp.106-109
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• 2019

Acromial fractures are well-documented complications subsequent to reverse shoulder arthroplasty (RSA), and most appear as stress fractures with no history of single trauma. To date, no study has reported the occurrence of acute displaced acromial fracture due to sudden strong deltoid contraction during heavy work. Displacement of the fracture results in a challenging surgery since it is difficult to obtain adequate fixation in thin and osteoporotic bones. We report a rare case of acute displaced acromial fracture after successful RSA treatment, using a novel technique of open reduction and internal fixation, applying two 4.5 mm cannulated screws and lateral clavicle precontoured plate.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.468-478
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• 2020

The wave interaction problem with a vertical slotted breakwater, consisting of impermeable upper, lower parts and a permeable middle part, has been studied theoretically. An analytical model was presented for the estimation of reflection and transmission of monochromatic waves by a slotted breakwater. The far-field solution of the wave scattering involving nonlinear porous boundary condition was obtained using eigenfunction expansion method. The empirical formula for drag coefficient in the near-field, representing energy dissipation across the slotted barrier, was determined by curve fitting of the numerical solutions of 2-D channel flow using CFD code StarCCM+. The theoretical model was validated with laboratory experiments for various configurations of a slotted barrier. It showed that the developed analytical model can correctly predict the energy dissipation caused by turbulent eddies due to sudden contraction and expansion of a slotted barrier. The present paper provides a synergetic approach of the analytical and numerical modelling with minimum CPU time, for better estimation of the hydrodynamic performance of slotted breakwater.

• Wind and Structures
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• v.16 no.1
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• pp.1-23
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• 2013

The wind-induced transient response of internal pressure following the creation of a sudden dominant opening during the occurrence of high external pressure, in low-rise residential and industrial buildings was numerically investigated. The values of the ill-defined parameters namely the flow contraction coefficient, loss coefficient and the effective slug length were calibrated by matching the analytical response with the computational fluid dynamics predictions. The effect of a sudden i.e., "instantaneously created" windward opening in the Texas Technical University (TTU) test building envelope was studied for two different envelope flexibility-leakage combinations namely: (1) a quasi-statically flexible and non-porous envelope and (2) a quasi-statically flexible and porous envelope. The responses forced by creating the openings at different time leads/lags with respect to the occurrence of the peak external pressure showed that for cases where the openings are created in close temporal proximity to the peak pressure, the transient overshoot values of internal pressure could be higher than the peak values of internal pressure in the pre-sequent or subsequent resonant response. In addition, the influence of time taken for opening creation on the level of overshoot was also investigated for the TTU building for the two different envelope characteristics. Non-dimensional overshoot factors are presented for a variety of cavity volume-opening area combinations for (1) buildings with rigid/quasi-statically flexible non-porous envelope, and (2) buildings with rigid/quasi-statically flexible and porous envelope (representing most low rise residential and industrial buildings). While the factors appear slightly on the high side due to conservative assumptions made in the analysis, a careful consideration regarding the implication of the timing and magnitude of such overshoots during strong gusts, in relation to the steady state internal pressure response in cyclonic regions, is warranted.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.36-44
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• 2000

Objective : The heart diseases are known as a major cause of sudden death, as well as a cause of poor life-quality of school-age children. But there have been few mass screening of heart diseases in these children in Korea. This study was done to estimate the prevalence of heart diseases of these population. Methods : We screened all elementary students(grade 1) in 12 cities and 16 counties(Gun) in Kyonggi province from 1992 to 1955. The first screening was done by auscultation of doctors and simultaneously by checking using 'auto-interpreter of EKG-cardiac sound' (Fukuda Densi ECP 50A). We conducted luther examinations to whom classified as being abnormal condition in first screening, by using EKG, chest x-ray, doppler echocardiograpy(if needed). Results : The total number of examined students was 161,308(92% of the population), the male were 83,238 and female were 78,070. The congenital heart diseases(CHD) patients were 290(18 per 10,000) - male 155(18.6 per 10,000) and female 135(17.3 per 10,000). The most frequent disease was ventricula septal defect(VSD, 45.5%), Atrial septal defect(ASD, 14.8%), Tetralogy of Follot(TOF, 11.7%), and Patent Dutus Arteriosis(PDA, 7.6%) in order. In female, the order was VSD(48.1%), ASD(13.3%), TOF(11.1%), and PDA(10.4%). The total number of EKG abnormality were 433(62.7 per 10,000) among 69,056 screened children in 1995. The complete right bundle branch block(CRBBB) and paroxymal ventricular contraction(PVC) were frequent(26.6%, 26.3% in each), and incomplete right bunddle branch block(IRBBB, 14.6%), paroxymal atrial contraction(PAC, 6.7%), abnormal Q(5.8%), Wolf-Pakinson-White syndrom (5.5%) in order. In female, the most frequent abnormality was PVC(29.8%), and CRBBB(19.9%) in order. Conclusion : We could present the stable prevalence of the rare heart disease. The prevalence of congenital heart diseases was 18.0 per 10,000 and of EKG abnormality was 62.7 per 10,000 among school children.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.3
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• pp.414-426
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• 1997

Numerical computations were conducted to characterize the three-dimensional laminar flow through an injector orifice having an inclined angle of 30 .deg.. For this study, the incompressible Navier-Stokes equations in generalized curvilinear coordinates, using a pseudocompressibility approach for continuity equation, were solved. The computations were performed using the finite difference implicit, approximately factored scheme of Beam and Warming and multi-block grids of complete continuity at block interfaces. The multi-block computations were validated for the steady state using direct comparison of multi-block solutions with equivalent single-block ones, including 2-D 180.deg. TAD and 3-D 90.deg. pipe bend. The comparisons between the numerical solutions and the flow field measurements for a tube with sudden contraction were presented in this work for solution validation. Computational results showed the nature of complex flow fields within the inclined injector orifice, including strong pressure-driven secondary flows in the cross stream induced by the effect of streamline curvature. In addition, asymmetric secondary flows were induced in the Reynolds number range above assumed laminar flow regime considered. However, turbulence calculations and grid dependency studies are needed for more accurate computations.

• Journal of ILASS-Korea
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• v.1 no.1
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• pp.76-84
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• 1996

The nozzle geometry and up-stream inject ion condition affect the characteristics of flow inside the nozzle. such as turbulence and cavitation bubbles. Flow details in fuel nozzle orifice with sudden contraction of cross sectional area have been investigated both experimentally and numerically. The measurements of velocities of internal flow in a scaled-up nozzle with different length to diameter rat io(L/d) were made by laser Doppler velocimetry in order to clarify the effect of internal flow on the characteristics of fuel spray. Mean and fluctuating velocities and discharge coefficients were obtained at various Reynolds numbers. The turbulent intensity and turbulence kinetic energy in a sharp inlet nozzle were higher than that in a round inlet nozzle. Calculations were also performed for the same nozzles as scaled-up experimental nozzles using the SIMPLE algorithm. External spray behavior under different nozzle geometry and up-stream flow conditions using Doppler technique and visualization technique were also observed.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.1-7
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• 2007

Based on the eigenfunction expansion method, the wave-absorbing performance of a square or circular pile breakwater was investigated. Flow separation resulting from sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of an exact energy loss coefficient is critical to enhancing the reliability of the mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code, and the energy loss coefficient can be obtained from the pressure difference between upstream and downstream. It was found that energy loss coefficient of circular pile is 20% that of a square pile. To validate the fitting equation for the energy loss coefficient, comparison between the analytical results and the experimental results (Kakuno and Liu, 1993) was made for square and circular piles with good agreement. The array of square piles also provides better wave-absorbing efficiency than the circular piles, and the optimal porosity value is near P=0.1.