• Korean Journal of Agricultural Science
• /
• v.45 no.2
• /
• pp.283-289
• /
• 2018

Agricultural gear reducers are used in a variety of agricultural machinery designs such as in agricultural tractors and transport cars, and even greenhouses. For greenhouses, a gear reducer is used to control windows on the side and the roof. Gear reducers for agricultural applications are designed using the empirical method because of the lack of a standard for experimentation. Simulation is necessary for the optimal design of an agricultural gear reducer. There are many advantages to this optimization such as low-cost maintenance, reduced size, and weight. In this study, bending and contact safety factor simulation for the gear reducer of a greenhouse was conducted by decreasing the face widths of helical gear shaft 2 and shaft 3 from 30.8 and 30 mm, respectively, at an interval of 4 mm. The bending and contact safety factors were calculated using AGMA standard. Simulation results showed that bending and contact safety factors decreased rapidly when the face width of the helical gear on shaft 2 was 30 mm and the face width of helical gear on shaft 3 decreased from 30.8 mm to 26.8 mm, suggesting that it would be safe to reduce the face width of the helical gear on shaft 3 to 26.8 mm. The reduction of the face width also reduced the weight of the agricultural gear. This study suggests that the agricultural gear reducer safety factor decreases as the face width decreases.

• Journal of Korean Society on Water Environment
• /
• v.22 no.1
• /
• pp.23-29
• /
• 2006

Biosorption technology was used to remove hazardous materials from wastewater, herbicide, heavy metals, and radioactive compounds, based on binding capacities of various biological materials. Biosorption process can be explained by two steps; the first step is that target contaminants is in contact with microorganisms and the second is that the adsorbed target contaminants is infiltrated with inner cell through metabolically mediated or physico-chemical pathways of uptake. Until recently, no information is available to explain the definitive mechanism of biosorption. The purpose of this study is to evaluate biosorption capabilities of organic matters using activated sludge and to investigate affecting factors upon biosorption. Over 49% of organic matter could be removed by positive biosorption reaction under anoxic condition within 10 minutes. The biosorption capacities were constant at around 50 mg-COD/mg-MLSS for all batch experiments. As starvation time increased under aerobic or anaerobic conditions, biosorption capacity increased since higher stressed microorganisms by starvation was more brisk. Starvation stress of microorganisms was higher at aerobic condition than anaerobic one. As temperature increased or easily biodegradable carbon sources were used, biosorption capacities increased. Consequently, biosorption can be estimated by biological -adsorbed capability of the bacterial cell-wall and we can achieve the cost-effective and non -residual denitrification with applying biosorption to the bio-reduction of nitrate.

• Journal of Biomedical Engineering Research
• /
• v.32 no.3
• /
• pp.198-206
• /
• 2011

Hearing devices like cochlear implant, vibrant soundbridge, etc. try to offer better sound for people. In hearing devices, several beamformers including conventional directional microphone are applicable to noise reduction. Each beamformer has different directional response and it could change sound intelligibility or quality for listeners. Therefore, we investigated the performance of three beamformers, which are first and second order directional microphone, and broadband beamformer(BBF) with a computer simulation assuming hearing device microphone configuration. We also calculated objective measurements which have been used to evaluate speech enhancement algorithms. In the simulation, a single speech and a single babble noisewere propagated from the front and $135^{\circ}$ azimuth degrees respectively. Microphones were configured in an end-fire array and the spacing was varied in comparison. With 3 cm spacing, BBF had about 3 dB higher enhanced SNR than that of directional microphones. However, enhancement of segmental SNR and frequency weighted segmental SNR were similar between the first order directional microphone and broadband beamformer. In addition when steady state noise was used, broadband beamformer showed the increased performance and had the highest enhanced SNR, and segmental SNR.

• Preventive Nutrition and Food Science
• /
• v.16 no.3
• /
• pp.210-216
• /
• 2011

Capsaicin is a pungent component of red pepper, which is widely consumed as food adjuncts. The present study was performed to investigate anti-obesity effects of capsaicin in diet-induced obese rats. Male Sprague-Dawley rats (n=14) were fed with a high-fat diet (Control) or high-fat diet containing 0.016% capsaicin (w/w) (Capsaicin) for 8 weeks. The final body weight and the mass of white adipose tissue were significantly lower in capsaicin supplemented group compared to control. Dietary capsaicin ameliorated lipid profiles with decrease in the plasma concentrations of triglycerides and total cholesterol, and decrease in the levels of total lipids and triglycerides in the liver. Activity of glycerol-3-phosphate dehydrogenase (GPDH), an indicator of triglyceride biosynthesis in white adipose tissue, decreased by 35% in the group supplemented with capsaicin. However, consumption of capsaicin increased the expression of uncoupling protein 2 (UCP2) in white adipose tissue, which is related to energy consumption. Our data suggests that capsaicin may reduce body weight and fat accumulation in high fat diet-induced obese rats. These effects may be mediated, at least partially, by the upregulation of UCP2 gene expression and its ability to inhibit GPDH activity.

• Archives of Craniofacial Surgery
• /
• v.13 no.1
• /
• pp.22-28
• /
• 2012

Purpose: In accordance to an increased interest in facial appearance and the popularization of computed tomography scanning, the number of diagnosis and treatment of blowout fractures has been increased. The purpose of this article is to review pure blowout fracture surgery through transconjunctival incision focusing on complications and their management. Methods: In this retrospective study, 583 patients, who had been treated for pure blowout fracture through transconjunctival incision from 2000 to 2009, were evaluated. Their hospital records were reviewed according to their sex, age, fracture site, preoperative presentations, time interval between trauma and surgery, and postoperative complications. Results: According to postoperative follow-up results, there were early complications that included wound dehiscence and infection (0.2%), hematoma (insomuch as extraocular movement is limited) (0.7%), lacriminal duct injury (0.5%), and periorbital nerve injury (0.7%). In addition, there were late complications that lasted more than 6 months, that included persistent diplopia (1.7%), extraocular movement limitation (0.9%), enophthalmos (1.0%), periorbital sensation abnormalities (1.0%), and entropion (0.5%). Conclusion: We propose the following guidelines for prevention of postoperative complications: layer by layer closure; bleeding control with the epinephrine gauzes, Tachocomb, and Tisseel; conjunctival incision 2 to 3 mm away from punctum; avoidance of excessive traction; performing surgical decompression and high dose corticosteroid therapy upon confirmation of nerve injury; atraumatic dissection and insertion of Medpor Barrier implant after securing a clear view of posterior ledge; using Medpor block stacking technique and BioSorb FX screw fixation; performing a complete resection of the anterior ethmoidal nerve during medial wall dissection; and making an incision 2 to 3 mm below the tarsal plate.

• Korean Chemical Engineering Research
• /
• v.45 no.6
• /
• pp.573-581
• /
• 2007

The present study deals with removal of $CO_2$ using various mesoporous materials impregnated with MEA (monoethanolamine). The mesoporous materials such as MCM-41, MCM-48 and SBA-15 were synthesised and then impregnated with 30, 50 and 70 wt% of MEA, respectively. XRD, FT-IR and SEM were used to evaluate the characterization of those. From the adsorption/desorption experiments for various materials, the adsorption capacity of these materials were found in the order of MCM-41> MCM-48> SBA-15. MCM-41 impregnated with 50 wt% of MEA showed the maximum adsorption capacity of $57.1mg-CO_2/gr-sorbent$ at $40^{\circ}C$. It is nearly 8 times higher than MCM-41 without impregnation of MEA. In the multiple cycle test of 20 times, MCM-41 impregnated with 50 wt% of MEA showed a constant adsorption capacity.

• The Journal of Advanced Prosthodontics
• /
• v.1 no.1
• /
• pp.26-30
• /
• 2009

STATEMENT OF PROBLEM. Qualitative and semi-quantitative methods have been developed for TMJ sound classification, but the criteria presented are completely inhomogeneous. Thus, to develop more objective criteria for defining TMJ sounds, electroacoustical systems have been developed. We used Joint vibration analysis in the BioPAK system(Bioresearch Inc., Milwaukee, USA) as the electrovibratography. PURPOSE. The aim of this study was to examine the TMJ sounds with repect to frequency spectra patterns and the integral > 300 Hz /< 300 Hz ratios via six-months follow-up. MATERIAL AND METHODS. This study was done before and after the six-months recordings with 20 dental school students showed anterior disk displacement with reduction. Joint vibrations were analyzed using a mathematical technique known as the Fast Fourier Transform. RESULTS. In this study Group I and Group II showed varied integral > 300 /< 300 ratios before and after the six-months recordings. Also, by the comparative study between the integral > 300 /< 300 ratios and the frequency spectrums, it was conceivable that the frequency spectrums showed similar patterns at the same location that the joint sound occurred before and after the six-months recordings. while the frequency spectrums showed varied patterns at the different locations that the joint sound occurred before and after six-month recordings, it would possibly be due to the differences in the degree of internal derangement and/or in the shape of the disc. CONCLUSIONS. It is suggested that clinicians consider the integral > 300 /< 300 ratios as well as the frequency spectrums to decide the starting-point of the treatment for TMJ sounds.

• Journal of Biomedical Engineering Research
• /
• v.29 no.1
• /
• pp.59-65
• /
• 2008

Nowadays, implantable hearing aids have been developed to solve the problems of conventional hearing aids. In case of fully implantable hearing aids, an implantable microphone is necessary to receive sound signal beneath the skin. Normally, an implantable microphone has poor frequency response characteristics in high frequency bands of acoustic signal due to the high frequency attenuation effect of skin after implantation to human body. In this paper, the implantable microphone is designed to reduce the high frequency attenuation effect of a skin by putting its resonance frequency at the attenuated range through a finite element analysis (FEA) simulation. The designed implantable microphone through the simulated results has been fabricated by manufacturing process using bio-compatible materials. By the several in-vitro experiments with pig skin, it has been verified that the designed implantable microphone has a resonance frequency around the starting part of the attenuated range and reduces the attenuation effect.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.60 no.5
• /
• pp.55-67
• /
• 2018

The objectives of this study were to monitor organic farming upland compared with conventional upland field and to evaluate nutrient loads reduction of surface cover effect with long-term historical climate data. APEX(Agricultural Policy Environmental eXtender) model was validated with experimental data and used for assessing surface cover scenarios for 30-year simulation periods. The validated values of RMSE(Root Mean Square Error), RMAE(Root Mean Absolute Error), $R^2$ and E(Nash-Sutcliffe efficiency) for runoff were 1.17-1.37 mm/day, 0.28-0.45 mm/day, 0.88-0.90 and 0.82-0.94 in two treatments, respectively. Those for water quality (nitrogen) were 0.05-0.16 kg/ha, 0.52-0.75 kg/ha, 0.67-0.72 and 0.32-0.70 in two treatments, respectively, and therefore the validated model showed good agreement with the observed runoff and nitrogen load for the study period. When decreasing the surface cover rate of organic farming field to 75%, 50%, 25%, and 0% (conventional field), average annual runoff increased by 7%, 15%, 23% and 31%, respectively. Under same condition of decreasing the surface cover rate, average annual nitrogen loads increased by 1.4 times, 1.7 times, 2.0 times, and 2.3 times compared with organic farming field, respectively. This study showed that it is possible to present an appropriate surface cover ratio to maintain conventional production and minimize nonpoint sources pollution for organic farming system, although long-term monitoring is needed to determine its effects on environmental concerns, crop competition, and other uncertainty.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.6
• /
• pp.645-652
• /
• 2016

A membrane module including grid was designed and introduced to MBR (membrane bio-reactor) for the purpose of better control of membrane fouling. It could be anticipated that the grid enhances the shear force of fluid-air mixture into the membrane surface by even-distributing the fluid-air to the membrane module. As MLSS concentration, packing density which is expressed in the ratio of the housing and the cross-sectional area of membrane fibers ($A_m/A_t$) and air-flow rate were changed, membrane foulings were checked by monitoring fouling resistances. The total fouling resistance ($R_c+R_f$) without grid installation (i.e., control) was $2.13{\times}10^{12}m^{-1}$, whereas it was reduced to $1.69{\times}10^{12}m^{-1}$ after the grid was installed. Regardless of the grid installation, the $R_c+R_f$ increased as the packing density increased from 0.09 to 0.28, however, the increment of resistance for the grid installation was less than that of the control. Increase in the air flow rate did not always guarantee the reduction of fouling resistance, indicating that the higher air flow rate can partially de-flocculate the activated sludge flocs, which led to severer membrane fouling. Consequently, installation of grids inside the housing have brought a beneficial effect on membrane fouling and optimum air flow rate is important to keep the membrane lowering fouling.