• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.6
• /
• pp.155-165
• /
• 2013

The effect of gaseous ammonia direct injection on the engine performance and exhaust emissions in gasoline-ammonia dual fueled spark-ignition engine was investigated in this study. Results show that based on the gasoline contribution engine power increases as the ammonia injection timing and duration is advanced and increased, respectively. However, as the initial amount of gasoline is increased the maximum power output contribution from ammonia is reduced. For gasoline-ammonia, the appropriate injection timing is found to range from 320 BTDC at low loads to 370 BTDC at high loads and the peak pressures are slightly lower than that for gasoline due to the slow flame speed of ammonia, resulting in the reduction of combustion efficiency. The brake specific energy consumption (BSEC) for gasoline-ammonia has little difference compared to the BSEC for gasoline only. Ammonia direct injection causes slight reduction of $CO_2$ and CO for all presented loads but significantly increases HC due to the low combustion efficiency of ammonia. Also, ammonia direct injection results in both increased ammonia and NOx in the exhaust due to formation of fuel NOx and ammonia slip.

• Environmental Engineering Research
• /
• v.22 no.4
• /
• pp.347-355
• /
• 2017

This study investigated how the combined changes in environmental conditions and nitrogen (N) deposition influence the mineralization processes and carbon (C) dynamics of wetland soil. For this objective, we conducted a growth chamber experiment to examine the effects of combined changes in environmental conditions and N deposition on the anaerobic decomposition of organic carbon and the emission of greenhouse gases from wetland soil. A chamber with elevated $CO_2$ and temperature showed almost twice the reduction of total decomposition rate compared to the chamber with ambient atmospheric conditions. In addition, $CO_2$ fluxes decreased during the incubation under the conditions of ambient $CO_2$ and temperature. The decrease in anaerobic microbial metabolism resulted from the presence of vegetation, which influences the litter quality of soils. This can be supported by the increase in C/N ratio over the experimental duration. Principle component analysis results demonstrated the opposite locations of loadings for the cases at the initial time and after three months of incubation, which indicates a reduction in the decomposition rate and an increasing C/N ratio during the incubation. From the distribution between the decomposition rate and gas fluxes, we concluded that anaerobic decomposition rates do not have a significantly positive relationship with the fluxes of greenhouse gas emissions from the soil.

• Environmental Engineering Research
• /
• v.21 no.2
• /
• pp.145-151
• /
• 2016

Biodrying is a pre-treatment method that applies biological and mechanical concepts to drying solid waste. In Malaysia, municipal solid waste (MSW) is unseparated and contains a high level of moisture, making the use of technology such as solid waste burning unsuitable and harmful. MSW containing organic material can be processed naturally until the moisture content of the waste is reduced. This study on MSW biodrying was carried out on a laboratory scale to measure the percent moisture content reduction and to monitor temperature patterns under different ventilation periods. This work was conducted using five biodrying reactors volumes of 50 liters each. Reactors were ventilated for 5, 10, 15, 20 and 30 min every 3 h, with a 3 bar air supply. The duration of this process was 14 days for all samples. The results showed that the optimum ventilation time was 10 min, with an 81.84% reduction in moisture content, and that it required almost half of the electricity cost required for the 20 and 30 min ventilations.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.46 no.2
• /
• pp.87-98
• /
• 2020

The aim of this study was to determine the efficacy of oral splints in reducing the intensity of pain in patients with temporomandibular joint dysfunction in both short and long-term treatment durations. Electronic databases, Cochrane Library, MEDLINE via PubMed, Web of Science, Egyptian Knowledge Bank, and EMBASE were searched for randomized controlled trials comparing different types of splints to non-occluding splints, behavioral therapy, pharmacotherapy, counseling, and no treatment. The risk of bias was assessed by using Cochrane risk of bias recommendations. Fixed and random effects were used to summarize the outcomes. The effect estimates were expressed as standardized mean differences (SMD) or risk ratios with a 95% confidence interval (CI). Subgroup analyses were carried out according to the treatment duration. Twenty-two studies met the inclusion criteria. A meta-analysis of short-term studies up to three months revealed no significant difference between the study groups. However, long-term studies exhibited a significant difference in pain reduction in favor of the control group. Total analysis revealed that the control group resulted in significant pain reduction (SMD 0.14, 95% CI 0.05-0.23, P=0.002, I²=0%). Oral splints are not effective in reducing pain intensity or improving function in patients with temporomandibular joint dysfunction.

• Herbal Formula Science
• /
• v.17 no.1
• /
• pp.163-173
• /
• 2009

Objectives : The goal of this study was to investigative the effect of Gardeniae Fructus (GF)as antidepressant in the forced swimming test(FST) model rats. Methods : The expressions of corticotropin-releasing factor(CRF), tyrosine hydroxylase (TH) and c-fos were measured by immunohistochemical method at paraventricular nucleus(PVN), locus coeruleus (LC) and ventral tegmental area(VTA). Results : The duration of immobility in FST was significantly decreased in the GF 100mg/kg groups (p<0.05). CRF expression was significantly decreased at PVN in the GF 100 mg/kg and 400mg/kg treated group in comparison with the control group, respectively (p<0.01). c-fos expression was decreased at PVN in the GF 100 mg/kg treated group with no significance. TH expression was significantly decreased in the GF 100 mg/kg and 400mg/kg treated group in comparison with the control group, at LC and VTA respectively (p<0.001). Conclusion : According to the results, it can be considered that Gardeniae Fructus has antidepressant effect by showing the reduction of immobility in FST through the reduction of CRF, TH expression.

• Herbal Formula Science
• /
• v.17 no.1
• /
• pp.129-140
• /
• 2009

Objectives : The goal of this study was to investigate the effect of Moutan Cortex as antidepressant in forced swimming test(FST) model. Methods : The expressions of corticotropin-releasing Factor(CRF), c-Fos and tyrosine hydroxylase(TH) were measured with immunohistochemical method at paraventricular nucleus (PVN), locus coeruleus(LC) and ventral tegmental area(VTA). Results : The duration of immobility in the forced swimming test was significantly decreased in the Moutan Cortex 100 mg/kg treated group in comparison with the control group(p<0.01). CRF and c-Fos expressions at PVN were decreased in the Moutan Cortex 100mg/kg treated group in comparison with the control group. But only the expression of c-Fos was shown the significance(p<0.05). TH expressions at LC and VTA were significantly decreased in the Moutan Cortex 100mg/kg and 400mg/kg treated group in comparison with the control group(p<0.001). Conclusion : According to the results, Moutan Cortex has the antidepressant effect by showing the reduced immobility through the reduction of c-Fos expression at PVN and the reduction of TH expression at LC and VTA.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.951-954
• /
• 2006

This Study introduces the design of a reactive type silencer for reducing impulse noises emitted from a high voltage COS fuse of a transformer. When a high voltage COS fuse becomes a short circuit by the over current, the peak sound pressure level above 150dB(A) is generated at the distance of 2m from a COS Fuse. For the purpose of the reduction of impulse noise, in this study. the reactive type silencers have been utilized. The performance of noise reduction for them can be expressed by insertion loss. The reactive silencers have been tested for 23 different types with each different porosity, hole diameter and depth. From the experimental results, it is found that the reactive silencer has an excellent performance to greatly suppress the impulse noise. The one-stage, two-stage and three-stage reactive type silencers have been shown to have the insertion losses of about from 35dB (A) to 25dB(A).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.5
• /
• pp.171-178
• /
• 2008

The combustion and exhaust emission characteristics were investigated in an DME fueled HCCI engine. Carbon dioxide, nitrogen and mixed gas, which was composed of carbon dioxide and nitrogen, were used as control parameters of combustion and exhaust emission. As the oxygen concentration in induction air, which was occurred by carbon dioxide, nitrogen and mixed gas, was reduced, the start of auto-ignition was retarded and the burn duration was extended due to obstruction of combustion and reduction of combustion temperature. Due to these fact, indicated mean effective pressure was increased and indicated combustion efficiency was decreased by carbon dioxide, nitrogen and mixed gas. In case of exhaust emission, hydrocarbon and carbon monoxide was increased by reduction of oxygen concentration in induction air. Especially, partial burning was appeared at lower than about 18% of oxygen concentration by supplying carbon dioxide. However it was overcome by intake air heating.

• KIEAE Journal
• /
• v.14 no.3
• /
• pp.55-63
• /
• 2014

This study selected and analyzed filter media that can be applied in non-point pollution reduction devices aimed at processing the source of pollution on site for road runoff that increases rapidly in rainfall-runoff in order to improve the water quality of urban areas. First, the factors that affect the quality of runoff caused by sources of non-point pollution include physical and social factors such as the usage of land around the area of water collection, type of pavement and movement of cars and people, as well as rainfall characteristics such as frequency, intensity, amount and duration of rainfall. Second, the purification tests of the filter media were processed for pH, BOD, COD and T-P, and the filter media showed to have initial purification effect at that items. However, the filter media showed to be very effective for the processing of SS, T-N, Zn and Cd from the beginning to the end. Third, for filter media, zeolite and vermiculite showed to be effective for processing SS, T-N, Zn and CD constantly, and composite filter media including zeolite showed to have strong processing effects. The authors conclude that this study can be applied to technical areas and policies aimed at reducing non-point pollution in urban areas and can also contribute to allowing eco-friendly management of rainfall as well as improvement of water quality.

• Journal of Korean Physical Therapy Science
• /
• v.3 no.1
• /
• pp.843-853
• /
• 1996

The purpose of this study was to determine whether extension exercise is effective in reducing low back pain. Nine patients with low back pain were randomly assigened to one of two groups-one was an experimental group in which the patient were treated with extension exercise(McKenzie method) and conservative therapy. The other was a control group in which the patients were treated with conservative therapy only. Treatment was performed for a period of ten days during Which we examed each patient three times: the first exam was done at the begining of treatment, the second after fives days, and the third after ten days. We used 'The Oswestry low back pain disability questionnaire'(r=.99) as the examination tool. The results were as follows: 1. Both experimental and control groups showed nonsignificant differences before and after treatment, and the between group difference was also non-significant(P>.05). 2. There was no effective reduction of low back pain by MecKenzie's extension exercise(p>.05). We admit that our study protocol had several shortcomings. If they had been accounted for, the result might have been different. Further study should be done with a better experimental design, a larger sample, and a longer experimental duration.