• Journal of the Korean Society of Marine Environment & Safety
• /
• v.18 no.3
• /
• pp.287-293
• /
• 2012

This paper has dealt with the probability of oyster shell desiccant cooling system driven by renewable energy of photo-voltaic effect. For this, fundamental experiments have been carried out focusing on the observation of dehumidifying effect of oyster shell and peltier elements used for air conditioning system. From this study, it is found that oyster shell has sufficient probability for using as a desiccant in air-conditioning system. Moreover, the heat releasing device(peltier element) can be used with direct current from PV cells so the system can be operated with high efficiency. As a result, the absolute humidity in a test chamber was reasonably controlled by oyster shell and peltier elements. Also the photo-voltaic energy from sun was enough for running power of this system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.3
• /
• pp.128-136
• /
• 2015

Reducing the building energy consumption has become one of the most important issues. However, the current engineering and technological involvement in energy analysis has been relatively low in the existing buildings. In the existing buildings, end-use analysis must be accompanied to calculate the exact amount in energy savings and such analysis should be conducted based on the energy billing data or measurement data by calibration process. Mostly, detailed energy simulation programs have been proposed for the analysis but, it is difficult to utilize them due to realistic problems. In this paper, we developed an end-use analysis tool that have input function for energy audit data and two case studies were conducted in the real-life office buildings located in Seoul, Korea. Mean Bias Error (MBE) and Coefficient of Variation of Root-Mean- Squreaed-Error (CV(RMSE)) are used for the criteria of comparison. Each index was calculated by using monthly utility bills of electricity and gas consumption. Results showed that MBE and CV (RMSE) represented with acceptable values of -0.1% and 5.7% respectively.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.104-104
• /
• 2011

The fuel economy estimates essentially serve two purposes : to provide consumers with a basis on which to compare the fuel economy of different vehicles, and to provide consumers with a reasonable estimate of the range of fuel economy they can expect to achieve. The current fuel economy label values utilize measured fuel economy over city driving cycles. However, this test driving mode can not be evaluated the variety factor of the real-world. These factors include differences between the way vehicles are driven on the road and over the test cycles, air conditioning use, widely varying ambient temperature and humidity, widely varying trip lengths, wind, precipitation, rough road conditions, hills, etc. The purpose of this paper is to account for three of these factors on the fuel economy : 1) on-road driving patterns (i.e. higher speeds and more aggressive driving (higher acceleration rates)), 2) air conditioning, and 3) colder temperatures. The new test methods will bring into the fuel economy estimates the test results from the five emissions tests in place today : CVS-75, HWFET, US06, SC03 and Cold CVS-75. Based on these new test methods, this paper discusses the characteristics of driving condition on Hybrid electric vehicle (HEV). And this paper assesses the fuel economy label of HEV.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.8
• /
• pp.541-546
• /
• 2008

A coolant operating condition in al fuel cell stack was an important factor to determine the temperature distribution which affected the fuel cell performance and relative humidity. In this study, the fuel cell performance was evaluated as a function of the coolant flow rate with the range of $0.1{\sim}0.8$ liter/min cell and the coolant inlet temperature of $20{\sim}82^{\circ}C$. The cell temperature increased with increasing the coolant inlet temperature and with decreasing the coolant flow rate. The coolant inlet temperature and flow rate to maintain the better performance of the fuel cell were in the range of $45{\sim}60^{\circ}C$ and $0.2{\sim}0.4$ liter/min cell, respectively. The experimental results showed that the optimal heat removal rate from the stack by coolant was $0.4{\sim}0.6W/cm^2$ cell.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.8 no.3
• /
• pp.397-412
• /
• 1996

This study aims to present the fundamental strategies to improve the Indoor Air Quality (IAQ) in apartment buildings. To investigate the concentration of indoor air pollutants such as radon, formaldehyde, and VOCs, both the document survey and the field measurement were conducted. In addition, to identify the source of the air pollutants, the laboratory experiment was carried out for various building materials. Finally, the minimum period to be reserved befor3e building occupation to ensure healthy IAQ, which largely depends on the ventilation rates, was simulated using a simple compuer program. The results of this study can be summarized as follows: 1. In case of newly-constructed apartment houses, concentrations of formaldehyde, VOCs and radon were found to exceed the standard. Meanwhile, at existing apartment houses, concentrations of VOCs, particularly toluene and xylene, highly exceeded the standasrd level. Concentrations of formaldehyde and radon, however, had been lowered according to the duration of occupation. 2. The laboratory experiment of concentration of pollutants per square meter of building material surface area showed that radon gas was much emitted from the gypsumboard; formaldehyde from flooring and wallpaper; and VOCs from paints and kitchen furnishings. The emission rates of formaldehyde and VOCs were proportional to air temperature. 3. According to the simulation of the minimum period to be reserved before occupation, newly-constructed airtight houses required about 190-200 days, and naturally ventialted houses with fully-open-windows required about 20-45days, in order to keep the level of radon gas lower than standard. Therefore, with the current practice, the date of occupation should be delayed for about 15 days.

• Journal of Ginseng Research
• /
• v.40 no.1
• /
• pp.55-61
• /
• 2016

Background: A number of neurological and neurodegenerative diseases share impaired cognition as a common symptom. Therefore, the development of clinically applicable therapies to enhance cognition has yielded significant interest. Previously, we have shown that activation of lysophosphatidic acid receptors (LPARs) via gintonin application potentiates synaptic transmission by the blockade of $K^+$ channels in the mature hippocampus. However, whether gintonin may exert any beneficial impact directly on cognition at the neural circuitry level and the behavioral level has not been investigated. Methods: In the current study, we took advantage of gintonin, a novel LPAR agonist, to investigate the effect of gintonin-mediated LPAR activation on cognitive performances. Hippocampus-dependent fear memory test, synaptic plasticity in the hippocampal brain slices, and quantitative analysis on synaptic plasticity-related proteins were used. Results: Daily oral administration of gintonin for 1 wk significantly improved fear memory retention in the contextual fear-conditioning test in mice.We also found that oral administration of gintonin for 1 wk increased the expression of learning and memory-related proteins such as phosphorylated cyclic adenosine monophosphate-response element binding (CREB) protein and brain-derived neurotrophic factor (BDNF). In addition, prolonged gintonin administration enhanced long-term potentiation in the hippocampus. Conclusion: Our observations suggest that the systemic gintonin administration could successfully improve contextual memory formation at the molecular and synaptic levels as well as the behavioral level. Therefore, oral administration of gintonin may serve as an effective noninvasive, nonsurgical method of enhancing cognitive functions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.26 no.6
• /
• pp.275-286
• /
• 2014

Light shelf is an efficient system that reduces the energy consumption by bringing the natural light down to the deep spaces inside of a building. However, the existing light shelves have limits in reducing energy usage, because the direction of the light flow is determined by the external environment such as the altitude of the sun and the azimuth. This current study presents a system that increases the efficiency of the light shelf by applying the Location-Awareness technology, in which the efficiency was verified through the performance evaluation. According to the examination of the technology for the Location-Awareness within residential space, 'Zigbee' type appears to be the most appropriate. The Location-Awareness technology operates the light shelf based on both the angle control axis and the light shelf angle control axis through the modularization of the reflector surface which is less affected by the external environment. The results of the performance evaluation showed that the movable light shelf that employs the Location-Awareness technology can reduce the energy consumption for lighting by 98.3% compared to the fixed light shelf and by 97.3% compared to the movable light shelf without Location-Awareness.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.10
• /
• pp.527-536
• /
• 2015

Studies for the reduction of lighting energy have been done using technologies such as user and location awareness. However, the focus of current research on location-based lighting control has been on energy reduction, which can lead to other issues including an imbalance in indoor illumination. This study proposes a lighting control system applying general illumination and technology for user and location awareness. The proposed lighting control system reduced lighting energy by 72.1%, 66.5% and 62.3% for 1, 2 and 3 users, respectively, compared to the On/Off lighting control system. This lighting control system causes an increase in lighting energy of 35.8% and 10.9% for 1 and 2 users compared to the lighting control system with user and location awareness, while a reduction of 9.4% was seen for 3 users. This means that the proposed system provides more effective energy reduction for a room with multiple occupants as it is based on the general lighting control scheme. The lighting control system applying general illumination and technology of user and location awareness improved the uniformity factor by 32.0%, 39.4% and 33.4% for 1, 2 and 3 users, respectively.

• The Journal of Advanced Prosthodontics
• /
• v.13 no.5
• /
• pp.292-303
• /
• 2021

PURPOSE. The aim of this in vitro study was to evaluate the effect of silane and universal adhesive applications on the micro-shear bond strength (µSBS) of different resin-matrix ceramics (RMCs). MATERIALS AND METHODS. A total of 120 slides (14 × 12 × 1 mm) were produced from 5 different RMC materials (GC Cerasmart [GC]; Brilliant Crios [BC]; Grandio blocs [GB]; Katana Avencia [KA]; and KZR-CAD HR 2 [KZR]) and sandblasted using 50 ㎛ Al₂O₃ particles. Each RMC material was divided into six groups according to the surface conditioning (SC) method as follows: control (G1), silane primer (G2), silane-free universal adhesive (G3), silane-containing universal adhesive (G4), silane primer and silane-free universal adhesive (G5), and silane primer and silane-containing universal adhesive (G6). Three cylindric specimens made from resin cement (Bifix QM) were polymerized over the treated surface of each slide (n = 12). After thermal cycling (10000 cycles, 5 - 55℃), µSBS test was performed and failure types were evaluated using a stereomicroscope. Data were analyzed using 2-way ANOVA and Tukey tests (α = .05). RESULTS. µSBS values of specimens were significantly affected by the RMC type and SC protocols (P < .001) except the interaction (P = .119). Except for G2, all SC protocols showed a significant increase in µSBS values (P < .05). For all RMCs, the highest µSBS values were obtained in G4 and G6 groups. CONCLUSION. Only silane application did not affect the µSBS values regardless of the RMC type. Moreover, the application of a separate silane in addition to the universal adhesives did not improve the µSBS values. Silane-containing universal adhesive was found to be the best conditioning method for RMCs.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.6
• /
• pp.456-464
• /
• 2007

This paper proposes a novel three-phase current-fed active clamp DC-DC converter for fuel cells. A single common active clamp branch is used to limit transient voltage across the three-phase full bridge and to realize zero-voltage switching(ZVS) in all switches. To apply for the power generation system current-fed type has been combined with the three-phase power conversion system. The proposed approach has the following advantages: an increase (by a factor of three) of input current and output voltage chopping frequencies; lower RMS current through the inverter switches with higher power transfer capability; reduction in size of reactive later components and the power conditioning system; better transformer utilization; increase of the system reliability. Therefore, the proposed three-phase current-fed active clamp DC-DC converter is appropriate for the boost type DC-DC converter for fuel cells and also applicable for the photovoltaic and battery charge system. The paper details the analysis, simulation and hardware implementation of the proposed system. Finally, experimental results with the proposed PWM strategy demonstrate the feasibility of the proposed scheme on a 500W prototype converter.