• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.185.1-185.1
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• 2014

본 연구에서는 Electrohydrodynamic (EHD) 젯 프린팅 시스템을 이용하여 graphene이 올려져 있는 유연성 있는 PET 기판 위에 Ag 용액을 그리드로 간격에 따라 타진하였다. Ag 그리드 간격을 200 um, 300 um, 400 um, 500 um로 증가시켰으며, 이때 UV/Vis spectrometry, four-point probe를 이용하여 전기적, 광학적 특성을 분석하였다. Graphene/Ag-grid 하이브리드 투명전극은 그리드 간격 400 um에서 21Ohm/sq.의 면저항과 550 nm에서 84.08%의 투과도를 확인하였다. 또한, graphene/Ag-grid 하이브리드 투명전극의 기계적 응력에 따른 전기적 안정성을 알아보기 위해 radius에 따른 bending, fatigue test와 twist bending, rolling test를 진행하였다. Fatigue bending은 speed 30 mm/s, outer bending radius 20 mm, inner bending radius 22.5 mm로 bending test를 5000번 진행하였으며, twist bending, rolling test를 각각 10000번 진행하였다. 이 결과를 통해 bending-release cycle 조건에서도 초기저항 대비 5% 이내의 매우 우수한 전기적 안정성을 나타냄을 확인하였다. 이러한 graphene/Ag-grid 하이브리드 투명전극의 우수한 특성을 얻음으로써, graphene 박막의 플렉시블 투명전극으로서의 적용가능성을 타진할 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.397-403
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• 2013

The demand for eco-friendly and higher fuel economy vehicles has helped develop eco-friendly and fuel-efficient vehicles such as hybrid vehicles. In a hybrid vehicle, the change in the battery charge after driving should be added to the fuel consumption as the equivalent fuel usage based on its own characteristics. Thus, the fuel efficiency of a hybrid vehicle cannot be improved simply by increasing the battery capacity. In this study, I attempt to improve the total fuel economy of a hybrid vehicle, including the equivalent fuel consumption, by modeling a fuel cell hybrid vehicle using Matlab Simulink, analyzing the usage zone of the fuel cell with the existing control strategy, and optimizing the power distribution of the battery and fuel cell in the main usage zone of the fuel cell.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1990-1996
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• 2012

In this paper, in order to improve the execution performance and serviceability of cross-platform applications frameworks based on the existing web applications, we design and implement a new hybrid application framework named as WApplE.js, which enables direct control of native UI(User Interface) of mobile operating systems and various resources via JavaScript. We first present the design results for the overall software structure and the configuration of every layer of WApplE.js, and then analyze the processes for calling and handling APIs in the implemented hybrid application framework. In addition, the results of comparison of features to the existing frameworks are presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.1-10
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• 2013

In this paper, the main cause on excitation of the combustion instability which may occur in the hybrid rocket motor with a diaphragm was studied. Hybrid rocket motor propulsion tests considering various experimental conditions such as with a diaphragm or not, a diameter of diaphragm, oxidizer mass flow rate, fuel length, etc were performed, and the combustion visualization for the inside of a hybrid rocket motor with a diaphragm was performed. With these experimental results, it was confirmed that the main cause of a large excitation was the hole-tone, and it was shown that the hole-tone model can be predicted experimental primary pressure oscillation frequency quite well.

• The KIPS Transactions:PartC
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• v.12C no.2 s.98
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• pp.223-228
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• 2005

The existing mobile communication system called DS/CDMA system, which is serviced widely nowadays, has some problems such as the severe ISI and multiple access interferences under the multi-path fading channel when applied to high-speed data transmission like multimedia transmission. To compensate these problems, we propose a sub-code multi-code hybrid DS/FH (Frequency Hopping) SS (Spread Spectrum) System by combining the multi-code system that restrains the multiple access interference with the hybrid DS/FH SS technique that reduces ISI(Intersymbol Interference) effect for high-speed transmission. Moreover, we implement and propose the sub-code technique to remedy the problems of the generic multi-code system. To verify the performance of the proposed system, the computer simulations are executed under the various channel environments.

• 발명특허
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• v.29 no.6 s.336
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• pp.50-53
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• 2004

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.513-524
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• 2016

The purpose of this study was to open two classes with the name of $21^{st}$ Leadership, run with two different hybrid teaching styles which are hybrid LZ type and hybrid lz type, and compare them with each other in order to analyze their effectiveness of hybrid model of the subject. The subjects of this study were 64 students who took these classes, and statistical analysis were analyzed through SPSS 21.0 program. As a result of the analysis, first, there were significant development in terms of the knowledge of leadership in both LZ and lz model. but the result of final exam in the group lz was shown only significant development. Second, in the case of unconditional self-acceptance there was significant development only in the group lz. Third, the development of leadership skills was shown only in the group lz. Implications of these results were concluded that the lz is more suitable for the subject of $21^{st}$ Leadership because this model can provide much more opportunities to develope interpersonal relationship skill than LZ model. In addition, suggestions for future research were discussed.

• Korean Journal of Optics and Photonics
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• v.31 no.2
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• pp.96-104
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• 2020

A catadioptric omnidirectional zoom optical system using a hybrid lens (COZOSH) that performs simultaneously two functions of a lens and a mirror was designed at the visible wavelength range for daytime unmanned surveillance, and its performance was analyzed. The hybrid lens has lots of advantages in terms of fabrication and assembly of a COZOSH, because of the obviation of a lens boring process and reduction of the number of optical components. Additionally, we designed the COZOSH to expand the compressed inner-image region of a donut image at low spatial frequencies. As a result, the optimized design performance of the optical system that satisfies all initial design specifications was obtained from calculation of the modulation transfer function, spot diagram, and tolerance analysis. We confirmed that the COZOSH is a passively athermalized optical system under conditions of temperature variation from -30℃ to 50℃, by using athermalization analysis during zooming.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.651-658
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• 2010

Sixteen concrete mixes reinforced with hybrid steel-polybinyl alcohol (PVA) fibers and a control concrete mix with no fiber were tested in order to examine the effect of the micro and macro fibers on the slump and different mechanical properties of concrete. Main variables investigated were length and volume fraction of steel and PVA fibers. The measured mechanical properties of hybrid fiber reinforced concrete were analyzed using the fiber reinforcing index and compared with those recorded from monolithic steel or PVA fiber reinforced concrete. The initial slump of hybrid fiber reinforced concrete decreased with the increase of the aspect ratio and the volume fraction of fibers. In addition, splitting tensile strength, modui of rupture and elasticity, and flexural toughness index of concrete increased with the increase of the fiber reinforcement index. Modulus of rupture and flexural toughness index of hybrid fiber reinforced concrete were higher than those of monolithic fiber reinforced concrete, though the total volume fraction of hybrid fibers was lower than that of monolithic fiber. For enhancing the flexural toughness index of hybrid fiber reinforced concrete, using the steel fiber of 60 mm length was more effective than using the steel fibers combined with 60 mm and 30 mm lengths.

• Journal of the Korea Society for Simulation
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• v.22 no.1
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• pp.21-30
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• 2013

A hybrid system is a combination of sub systems which have different types of state and time: a typical example is a combination of discrete event and continuous systems. A HDEVS(Hybrid DEVS) formalism was proposed for modeling and analyzing a hybrid system. The HDEVS formalism allows modelers to construct a hierarchical and modular model based on the mathematical set theory. Because the HDEVS formalism was applied to the distributed and interoperated simulators, modelers should make several heterogenous models dividing a target system. Hence, this paper proposes an extended hybrid coupled model of HDEVS formalism and an integrated hybrid modeling methodology in contrast to the existing simulation framework on interoperable simulators. By applying the proposed modeling method, a target system can be translated to a hybrid model in a similar form as the target system. This paper also contains a simulation engine design for the proposed modeling methodlogy and a case study which simulates water tank control systems.