• Journal of Hydrogen and New Energy
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• v.24 no.4
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• pp.275-281
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• 2013

This study was conducted to increase the amount of bio-hydrogen production from microalgae(Chlorella vulgaris) in batch reactors by thermal pre-treatment. The optimization of thermal pre-treatment was conducted using statistic experimental design of response surface methodology. Two experimental parameters of temperature and reaction time were considered. The optimization condition was founded at the coded variables of <0.52, -0.07> corresponding to the experimental of heating temperature of $95.6^{\circ}C$ and reaction time of 57.9 min, respectively. Under the optimal condition, the maximum hydrogen production was predicted to 25.3mL $H_2/g$ dry cell weight (dcw), which was 9.1 times higher value of control(2.8mL $H_2/g$ dcw).

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2071-2075
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• 2003

Pressure variation is one of the major sources on noise emission in the oil hydraulic piston pumps. Therefore, it is necessary to clarify about pressure variation characteristics of the oil hydraulic piston pumps to reduce noise. Pressure variations in a cylinder at trapping region were measured during pump working period with discharge pressures, rotational speeds. The effect of pre-compression of the discharge port with three types valve plates also investigated. It was found that the pressure variation characteristics of oil hydraulic piston pumps deeply related with pre-compression design of the discharge port. Also, it was found that the pressure overshoot at trapping region can reduce by use of pre-compression at the end of the discharge port in valve plate

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1020-1021
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• 2015

본 논문에서는 상용전압 AC 220V를 인가전압으로 사용하여 PMIC(Power Management IC)의 구동에 적합한 전압을 인가해주는 Pre-Regulator를 설계하였다. 설계된 Pre-Regulator는 상용전압을 사용하기 때문에 Device의 내압이 700V인 Magnachip $0.35{\mu}m$ BCD 공정을 이용하여 설계되었으며, 회로의 구성은 저전압 입력 보호 기능 및 JFET의 구동 제어를 위한 Under Voltage Lock Out(UVLO)회로, 전압조정기(Regulator)의 기준전압을 생성해주는 밴드갭 기준전압 발생(Bandgap Reference)회로, LDO(Low Drop Out)회로로 구성되어있다.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.1
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• pp.1-6
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• 2014

In order to evaluate the performance of ground heat source in thermal labyrinth on pre-heating in winter season and pre-cooling in summer season, the followings are made as a conclusion through case study of H project by using the weather data from Korea meteorological administration and CFD model. By making outdoor air inlet via ground heat source in thermal labyrinth for conduction, convection and etc., the temperature rise is $13.4^{\circ}C$as the effect of pre-heating in winter season. On the other hand, as the effect of pre-cooling in summer season, the temperature decrease is $7.2^{\circ}C$. The energy saving rate by the application of ground heat source in thermal labyrinth is 9.1%.

• Journal of Ocean Engineering and Technology
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• v.30 no.6
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• pp.431-439
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• 2016

This paper reports a numerical method for determining the resistance and self-propulsion performance of an asymmetric pre-swirl stator used as an energy saving device by cancelling a propeller's rotational energy. The present asymmetric pre-swirl stator propulsion system consists of three blades at the port and one blade at the starboard, which can effectively recover the biased rotating flow. This paper provides the design concept for the present asymmetric stator, which produces more efficient results than a conventional propeller.

• KCI Concrete Journal
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• v.12 no.1
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• pp.69-77
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• 2000

The reinforced concrete(RC) flexural members strengthened with steel plate/CFS at soffit have initial stresses and strains in reinforcements and concrete caused by the service loads at the time of retrofitting works. These initial residual stresses and strains of strengthened beams may affect the flexural performance of the rehabilitated beams. The objective of this study is to evaluate and verify the effectiveness of rehabilitation by external bonded steel plates and CFS to the tension face of the beams under three conditions of pre-loading. Thirteen beam specimens are tested and analyzed. Main test parameters are pre-loading conditions, strengthening materials and reinforcement ratio of specimens. The effect of test parameters on the strengthened beams is analyzed from the maximum load capacity, load-deflection relationship, state of stress of the materials. crack propagation phase, and failure modes. Both test results and design formulas of ACI Code provisions are compared and evaluated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.485-488
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• 2005

In this paper designed available pre-amplifier to Ultrabroadband power amplifier. Designed pre-amplifier used WJ company's AM1 which frequency characteristic and noise characteristic are superior. Designed to have superior VSWR characteristic and frequency characteristic covering broadband of 100MHz ${\sim}$ 3GHz using feedback.

• Journal of the Korean Society of Combustion
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• v.16 no.2
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• pp.40-46
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• 2011

The diesel pre-heater has being used in cabin heating and coolant heating of engine to reduce the engine warm up time for commercial vehicle. The pre-heaters are classified as diesel spray combustor and it forms diffusion flame. By using swirler, a recirculation flow of hot product gases is established near the fuel nozzle and it helps the maintaining of diffusion flame. The design difference of swirler can affect on reaction characteristics and temperature distribution inside pre-heater. The purpose of this study is the investigation of the effect of swirler configuration on combustion characteristics. To solve spray combustion problem, the Euler-Lagrange approach discrete model is used to track droplet trajectory and evaporation history. The PDF equilibrium model is used for chemical reaction model. These models are implemented into the FLUENT code.

• Parasites, Hosts and Diseases
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• v.61 no.3
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• pp.231-239
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• 2023

Toxoplasma gondii is an intracellular parasitic organism affecting all warm-blooded vertebrates. Due to the unavailability of commercialized human T. gondii vaccine, many studies have been reported investigating the protective efficacy of pre-clinical T. gondii vaccines expressing diverse antigens. Careful antigen selection and implementing multifarious immunization strategies could enhance protection against toxoplasmosis in animal models. Although none of the available vaccines could remove the tissue-dwelling parasites from the host organism, findings from these pre-clinical toxoplasmosis vaccine studies highlighted their developmental potential and provided insights into rational vaccine design. We herein explored the progress of T. gondii vaccine development using DNA, protein subunit, and virus-like particle vaccine platforms. Specifically, we summarized the findings from the pre-clinical toxoplasmosis vaccine studies involving T. gondii challenge infection in mice published in the past 5 years.

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.725-739
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• 2022

This study aims to analyze what elementary school pre-service teachers focused on and what challenges they faced in designing and producing a guided science inquiry program based on augmented reality (AR) and to provide some implications for teachers' professionalism and teacher education. To this end, focusing on the cases of pre-service teachers who designed and created AR-based guided inquiry programs, the researchers extracted and categorized the pre-service teachers' focus and challenges from the program design and production stages. As a result, in the program design stage, the pre-service teachers tried to construct scenarios that could promote students' active inquiry process. At the same time, drawing on the unique affordances of AR, the pre-service teachers focused on creating vivid visual data in a 3D environment and making meaningful connections between virtual and real-world activities. The pre-service teachers faced challenges in making use of the advantages of AR technology and designing an inquiry program due to a lack of background knowledge about CoSpaces, a content creation program. In the program production stage, the pre-service teachers tried to make their program easy to handle to improve students' concentration on inquiry activities. In addition, challenges of programming using CoSpaces were reported. Based on these results, educational implications were discussed in terms of the pedagogical uses of AR and teachers' professionalism in adopting AR in science inquiry.