• Transactions of the Korean hydrogen and new energy society
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• v.23 no.2
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• pp.183-190
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• 2012

The research shows the experiment results according to the combustion characteristics and configuration of the linear generator of powerpack for the generating power applying the 2-stroke compact linear engine. The powerpack used in this paper consists of 2-stroke linear engine, linear generator and air compressor parts. For identifying the combustion characteristics and generating power of linear engine, some parameters were varied sucha as electric load, fuel input calorie, spark timing delay and equivalence ratio. Also generating power was confirmed at each operation conditions, when the air gap length of linear generator part was changed as each 1.0 mm and 2.0 mm. During the all operations, intake air was inputted under the wide open throttle. Mass flow rate of air and fuel was changed using mass flow controller, after these were premixed by premixture device, and then premixed gas was supplied directly into each cylinder. As a result, piston frequency and combustion characteristics were different at each conditions according to parameters affecting the combustion such as fuel input calorie, resistive load, spark timing delay and equivalence ratio. Consequently, these had an effect on generating power.

• Journal of Korean Foot and Ankle Society
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• v.7 no.1
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• pp.109-114
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• 2003

Purpose: The purpose of this study is to evaluate the effectiveness and indications of the modified Essex-Lopresti reduction in calcaneal fractures. Materials and Methods: We reviewed retrospectively 41 cases of displaced intraarticular calcaneal fractures. The fracture was reduced with Essex-Lopresti technique with modification in compression of the lateral wall with the specially designed compression device instead of the operator's hands. We evaluated the results of treatment by AOFAS scale and the radiographic parameters including the Bohler's angle, calcaneal width, calcaneofibular distance and the congruency of the posterior facet. Results: Boler's angle was restored from 11 to 29.6 degrees on average, heel width was reduced to 112% of contralateral value, the calcaneofibular gap was restored up to 87.9% of contralateral side, and the articular surface of the posterior facet was restored less than 2 mm of step off and less than 2 mm of gap. AOFAS scale averaged 87 points. The quality of reduction was best in Sander's type II fractures. Small sized fragments in type III fractures could not be reduced. The results were better when the reductions were performed within 24 hours of injury. Conclusion: The modified Essex-Lopresti reduction was less invasive, easy to perform, and the results of treatment were similar to those of open reduction; it seemed to be a reasonable alternative for the selected intraarticular calcaneal fractures.

• The Journal of Advanced Prosthodontics
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• v.11 no.6
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• pp.341-349
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• 2019

PURPOSE. A novel retentive type of implant prosthesis that does not require the use of cement or screw holes has been introduced; however, there are few reports examining the biomechanical aspects of this novel implant. This study aimed to evaluate the biomechanical features of cementless fixation (CLF) implant prostheses. MATERIALS AND METHODS. The test groups of three variations of CLF implant prostheses and a control group of conventional cement-retained (CR) prosthesis were designed three-dimensionally for finite element analysis. The test groups were divided according to the abutment shape and the relining strategy on the inner surface of the implant crown as follows; resin-air hole-full (RAF), resin-air hole (RA), and resin-no air hole (RNA). The von Mises stress and principal stress were used to evaluate the stress values and distributions of the implant components. Contact open values were calculated to analyze the gap formation of the contact surfaces at the abutment-resin and abutment-implant interfaces. The micro-strain values were evaluated for the surrounding bone. RESULTS. Values reflecting the maximum stress on the abutment were as follows (in MPa): RAF, 25.6; RA, 23.4; RNA, 20.0; and CR, 15.8. The value of gap formation was measured from 0.88 to 1.19 ㎛ at the abutment-resin interface and 24.4 to 24.7 ㎛ at the abutment-implant interface. The strain distribution was similar in all cases. CONCLUSION. CLF had no disadvantages in terms of the biomechanical features compared with conventional CR implant prosthesis and could be successfully applied for implant prosthesis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.548-553
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• 2004

In this paper, single, two, and three-section microstrip directional couplers are implemented for realizing the high directivity characteristics. The achievement of the high directivity with microstrip configuration is carried out by the distributed capacitor to decrease the even and odd mode phase difference. Capacitive compensation is performed by gap coupling of open stub formed in sub-coupled line. Therefore, insertion loss and power handling capability are not affected by the gap coupling. The proposed structure is easy to fabricate and incorporate another microwave device due to the planner microstrip. We designed and fabricated single, two, and three-section directional coupler with 20 ㏈ coupling. In spite of microstrip structure, the capacitive compensation structure shows 30 ㏈, 27 ㏈, and 25 ㏈ of directivity in single, two, and three-section directional couplers, respectively.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.73-79
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• 2008

We propose a novel metal-waveguide structure for sustaining long-range surface-plasmon-polaritons (LRSPP). The LRSPP waveguides are composed basically of two asymmetric metal layers: a very thin, finite-width metal strip on top of a metal slab with a dielectric gap in between them. Mode cut-off of LRSPPs excited on the double-metal waveguides is characterized by consistently investigating their dispersion relations and mode profiles. We also confirm experimentally the existence of low-loss, well-confined LRSPP modes by measuring far-field outputs emerging from an edge of the asymmetric double-metal waveguides. In the experiment, we have fabricated several types of SPP waveguide devices including straight lines, S-bend, and Y-branch consisting of gold strips (20 nm-thick, $5{\mu}m$-wide). Overall propagation loss of the proposed double-metal waveguides is quite comparable to that of single metal-strip waveguides, in addition the mode sizes can be tuned by increasing the core-insulator gap between the metal layers to get a higher coupling efficiency with a single-mode fiber in telecom wavelength. The proposed LRSPP waveguides may open up realization of SPP-waveguide sensors or nonlinear SPP-devices by replacing the core-insulator with a bio-fluid or a nonlinear medium.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.1
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• pp.14-23
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• 2001

The characteristics of tidal circulation with Hyungsan River discharges in Youngil Bay by the numerical experiments is elucidated. For the simulation of tidal residual currents related to inflow by the river discharges in Youngil Bay located in the southeastern part of Korean Peninsula, the two-dimensional numerical experiment is peformed. The tidal elevation boundary conditions of the 4 main tidal harmonic constituents (M₂, S₂, K₁ and O₁) on the open boundary and river discharges at the river boundary are considered. The computed results obtained from numerical experiment showed good agreements with the field observation ones. The residual currents generally flow toward the inner bay through the western (Dalman-Gap) and central areas of the bay, and then the currents go toward the outer bay along the eastern shore (Changgi-Gap) of the bay with anti-clockwise circulation. Especially, in the numerical experiment without Hyungsan River discharges, these flow patterns are disappeared. Based on the results, it showed that the Hyungsan River discharges play the dominant role in the patterns of tidal residual currents. This flow pattern of tidal residual currents are important mechanism of water quality, material transport in Youngil Bay.

• Korea Journal of Hospital Management
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• v.26 no.3
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• pp.43-55
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• 2021

Purposes: The purpose of this study is to confirm the effect of mother's nationality on screening rates for infants and children health screening. We intend to find out if there is a difference in health level between infants of multicultural families and infants of domestic families, and contribute to policies to enhance future national health levels by providing information on them. Methodology: Data for those who received the first infant and children health screening between 2012 and 2018 were obtained from the National Health Insurance Service(NHIS) DB. Frequency analysis, chi-square test and logistic regression analysis were performed with the SAS 9.4 program, and the case where all the 1st to 3rd checkups were completed was defined as type I, and the case of all the 1st to 7th checkups completed, type II. Findings: Complete screening rates for type I and type II were 45.8% and 20.0%, respectively. Especially, complete screening rate of infants whose mothers nationality is foreign is only 3-4th of that of domestic mothers, and it also differed according to nationality. Practical Implications: The difference in the screening rate according to the mother's nationality is likely to lead to a health gap between multicultural families and domestic families. It is necessary to promote and encourage proper monitoring and health management through continuous health screening for infants and children.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.89-94
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• 2021

Recently, the boundaries between people who produce and consume digital contents disappears due to the massive developments in information and communications technology (ICT) and the rapidly increasing spread of smartphones unlike in the traditional mass media (e.g., newspapers, radios, and TVs). Through the open service platform, the problem perception for each individual remains the same, but the problem solving methods varies as the service types have been diversified. The creation of added value through the growth of the new media platform industry is expected to enrich our lives, but it can also cause severe social side effects. For example, communication problems between social classes due to the information gap have led to generational conflict, and if such problems persist, it can cause national and social losses. Therefore, this paper analyzes the policy efforts to resolve the information gap and the necessity of the legalization of multimedia literary education to maximize the synergy effect through psychological model.

• Journal of Bio-Environment Control
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• v.29 no.1
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• pp.52-61
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• 2020

The natural change of winter night temperature from 00:00 to 04:30 O'clock with the different height of thermal screen in a venlo type glasshouse (W59×L68×H5.9 m) was studied using computational fluid dynamics (CFD). At the early stage of CFD analysis, the room temperature decrease of glasshouse with the 5.9 m height of thermal screen were faster than it with the 4.1m height of thermal screen, but at 2 hr after analysis it was slower than in it with the 4,1m, the temperature difference was 0.6℃ after 4 hr. If we consider that turn on the heater when the temperature were decrease below 13℃ at 1hr after CFD analysis, it is good for energy saving in the glasshouse with the 4.1 m height of thermal screen rather than in it with the 5.9 m height, because of the temperature decrease were slow during 2 hrs after analysis. The airflow at the height of 2 m which were grown tomato were fast and wide in the glasshouse with the 5.9 m height thermal screen rather than in it with the 4.1 m, the speed difference was 0.034m·s^-1 at 1hr after CFD analysis. The effect of temperature decrease in summer season were compared with the different height of shading screen from 12:00 to 14:30 O'clock. The height of shading screen were 5.7, 3.9 m, the gap of it were 30%. The air-inflow quantity by the fan with duct at lower part of venlo glasshouse was 0.67 ㎥·s^-1 until 1hr and to increase 3 times of it from 1hr after analysis. The roof window were open 100%. Until 1hr of CFD analysis, the temperature in the 30% open of shading screen was 0.9℃ higher than in the none shading screen. From 13:00 O'clock when the air-inlet quantity to increase 3 times, the temperature in case 30% gap of shading screen were decreased compare with the none shading screen, the temperature difference was 0.5℃ at 14:30 O'clock. The temperature on the floor surface in case 30% gap of shading screen were lower with it's height increase, the temperature difference was 8℃ compare with none shading screen. The relative humidity difference were insignificant by the height and gap of shading screen.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.4
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• pp.39-49
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• 2015

Since most medical facilities and medical personnel are concentrated in urban areas in South Korea, an imbalance of access to medical facilities causes a gap in medical resource availability between urban and rural areas. Accessibility to medical facilities is a means of assessment that evaluates a measure of inequality in utilization of medical resources. The evaluation of accessibility uses Euclidean distance, in general; however, this method has its limits in that Euclidean distance cannot reflect actual distance. This study aims to estimate real road distance from village halls to medical facilities in rural areas using Open Application Programming Interface (Open API) of an internet portal site. Using real road distance, we evaluated medical accessibility and compared it with Euclidean distance. The accessibility to primary medical institutions was valued relatively well, but secondary and tertiary medical institutions were vulnerable in Pyeonchang-gun. Comparing Euclidean distance with real road distance from village halls to medical facilities, real road distance appeared to be approximately 1.4 times that of Euclidean distance. This calculation is similar to the circuity factor of Gangwon-do in Korea that estimated to fix the limits of Euclidean distance and assumed real road distance.