• Analytical Science and Technology
• /
• v.30 no.1
• /
• pp.39-48
• /
• 2017

Roxithromycin (RXT), which is an antibiotic used to treat respiratory tract and urinary infections, is official in Korean Pharmacopoeia (KP) and is marketed in various dosage forms including tablet, granule, suspension, and tablet for suspension in Korea. This study presents how a universal and reliable method to quantify RXT in bulk drug and formulations was developed. Effects of factors including column type, buffer concentration, type and concentration of organic solvent, buffer pH, and type and concentration of mobile phase additive, were examined, and some categorical or crucial factors including the types of column, organic solvent, mobile phase additive and the buffer pH were optimized by one-factor-at-a-time approach. Subsequently, concentrations of the buffer and additive and column temperature were optimized by response surface methodology using Box-Behnken design aiming to acquire the RXT peak of good shape. The optimized method employed a Phenomenex Gemini $5{\mu}$ C18 110A ($150{\times}4.60mm$, $5{\mu}m$) maintained at $30^{\circ}C$ with the mobile phase consisting of 25 mM phosphate buffer (pH 6.0) with 0.3 % tetrabutylammonium hydroxide and methanol at a ratio of 37:63 (v/v). Method validation results showed that the developed method was linear, precise, and accurate. Compared to the compendial methods in KP 10 that exhibited a significant tailing of the RXT peak despite using unfavorably high buffer concentrations and were not harmonized among bulk drug and formulations, this method could be universally applied to RXT bulk drug and marketed products in various dosage forms and thus was adopted in KP 11.

• Journal of Biosystems Engineering
• /
• v.39 no.1
• /
• pp.21-33
• /
• 2014

Background: Significant technological development and changes happened in the tractor industries. Contrariwise, the test procedures of the major standard development organizations (SDO's) remained unchanged or with a little modification over the years, demanding new tractor test standards or improvement of existing ones for tractor performance, safety, and comfort. Purpose: This study focuses on reviewing the research trends regarding performance, safety and comfort evaluation of agricultural tractors. Based on this review, few recommendations were proposed to revise or improve the current test standards. Review: Tractor power take-off power test using the DC electric dynamometer reduced human error in the testing process and increased the accuracy of the test results. GPS signals were used to determine acceleration and converted into torque. High capacity double extended octagonal ring dynamometer has been designed to measure drawbar forces. Numerical optimization methodology has been used to design three-point hitch. Numerous technologies, driving strategies, and transmission characteristics are being considered for reducing emissions of gaseous and particulate pollutants. Engine emission control technology standards need to be revised to meet the exhaust regulations for agricultural tractors. Finite Element Analysis (FEA) program has been used to design Roll-Over Protective Structures (ROPS). Program and methodology has been presented for testing tractor brake systems. Whole-body vibration emission levels have been found to be very dependent upon the nature of field operation performed, and the test track techniques required development/adaptation to improve their suitability during standardized assessment. Emphasizes should be given to improve visibility and thermal environment inside the cab for tractor operator. Tractors need to be evaluated under electromagnetic compatibility test conditions due to large growing of electronic devices. Research trends reviewed in this paper can be considered for possible revision or improvement of tractor performance, safety, and comfort test standards.

• Analytical Science and Technology
• /
• v.23 no.6
• /
• pp.551-559
• /
• 2010

This study was conducted to establish an analytical method for the determination of seven nitrosamines in chlorinated tap water by precolumn derivatization followed by high performance liquid chromatography coupled with fluorescence detection. The derivatization procedure was optimized for denitrosation and dansylation, and then two extraction methods, liquid-liquid extraction (LLE) with dichloromethane and solid phase extraction (SPE), were compared. The SPE method employing the optimized derivation procedure showed higher extraction recovery (54.4-88.7%) and reproducibility (1.9-19.4%) than the LLE method (51.4-87.7% and 4.2-33.3%, respectively). The method detection limits were between 0.5 and 4.4 ng/L. When chlorinated water samples were collected from two treatment plants and ten household taps, and analyzed for nitrosamines, Nnitrosodimethylamine (NDMA) was the major compound found between 26.1 and 112 ng/L.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.5
• /
• pp.403-409
• /
• 2008

Polymer electrolyte membrane fuel cell (PEMFC) is very interesting power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, improvement of performance, effect of temperature and initial start at low temperature. These problems can be approached to be solved by using experiment and mathematical method which are general principles for analysis and optimization of control system for heat and hydrogen detecting management. In this paper, insulation vessel and control system for stable operation of fuel cell at low temperature were developed for experiment. The constant temperature capability and the heating time at sub-zero temperatures with insulation control system were studied by using a heating bar of 60W class. PEMFC stack which was made by 4 cells with $50\;mc^2$ active area in each cell is a thermal source. Times which take to reach constant temperature by the state of insulation vacuum were measured at variable environment temperatures. The test was performed at two conditions: heating mode and cooling mode. Constant temperature capability was better at lower environment temperature and vacuum pressure. The results of this experiment could be used as basis data about stable operation of fuel cell stack in low temperature zone.

• KSBB Journal
• /
• v.32 no.1
• /
• pp.71-82
• /
• 2017

To verify anti-diabetic effect of oligopeptide with His-Pro repeats (mHP peptide), the oligopeptide was first secreted and optimized using the secretion vector, pRBAS with alkaline protease gene promoter and the signal sequence in Bacillus subtilis and directly the anti-diabetic effect of the mHP peptide was investigated in insulinoma cell, RINm5F cell line. The oligopeptide gene was obtained by annealing oligonucleotides with repeated His-Pro sequence and finally was constructed as 18 dipeptides (108 bp and 4.0 kDa) coding gene, named oligopeptide with His-Pro repeats (mHP peptide) to make cyclo(His-Pro) known to be anti-diabetic effects. The region encoding the oligopeptide gene was subcloned into the pRBAS secretion vector (E.coli-Bacillus shuttle vector) after PCR amplification using the designed primers including initiation and termination codons and His tag, named pRBAS-mHP (6.56 kb). To optimize secretion of the oligopeptide, various culture conditions were investigated in Bacillus subtilis LKS. As a result, the secreted oligopeptide was maximally measured (approximately $59.6{\mu}g/mL$) in 3 L batch culture and the highest secretion was achieved at $30^{\circ}C$, PY medium, and carbon sources (particularly barley and glycerol). In the RINm5F cells treated with 2 mM STZ, the oligopeptide treatment (0.1 mg/mL) restored the cell viability (10%) and reduced the nitric oxide (NO) generation (35%) and DNA fragmentation (90%). And also, insulin secretion level was increased to 17% higher than in STZ-treated RINm5F cells. These results suggest that the oligopeptide with His-Pro repeats could be a candidate material for anti-diabetic agent against STZ-induced diabetes.

• Journal of Medicine and Life Science
• /
• v.17 no.1
• /
• pp.7-15
• /
• 2020

The field triage guidelines have been widely implemented in the Korean trauma system. This study aimed to evaluate and validate whether it is reliable to use the field triage guidelines for predicting severe traumatic brain injury (TBI) and traumatic spinal injury (TSI) patients. This study retrospectively analyzed in-hospital cohort registries of all TBI and TSI patients, who visited the emergency department (ED) of the Jeju National University Hospital from 1 January 2013 to 31 December 2015. The primary outcome was defined as TBI and TSI patients with an injury severity score (ISS)>15. Secondary outcomes were defined as cases in which one or more of the following conditions: in-hospital death, ISS>15, admission to the intensive care unit, emergency surgery. We enrolled 14,889 TBI and TSI patients who visited ED, of which 7,966 (53.5%) were triage positive. The overall sensitivity, specificity and area under the curve (AUC) of the full cumulative field triage guidelines step's model (Step 1+3+4 criteria) for primary outcome were 82.8%, 47.0%, and 0.646, respectively. In the results for secondary outcomes, the specificity did not show a significant difference, but the sensitivity decreased to 66.5% and AUC to 0.568. The results of this study suggest that further optimization of the field triage guidelines is needed to identify high-risk TBI and TSI patients.

• Journal of the Society of Naval Architects of Korea
• /
• v.29 no.2
• /
• pp.115-122
• /
• 1992

A sandwich element is a special Hybrid structural form of the composite construction, which is consisted of three main parts : thin, stiff and relatively high density faces separated by a thick, light, and weaker core material. In a sandwich construction, the shear deformation of the faces. Therefore, in the calculation of the bending stiffness, the shear effect should be included. In this paper, the minimum weight is selected as an object function, as the weight critical structures are usually composed of these kind of construction. To obtain the minimum weight of sandwich panel, the principle of minimum potential energy is used and as for the design constraints, the allowable bending stress of face material, the allowable shear stress of core material, the allowable value of panel deflection and the wrinkling stress of faces are adopted, as well as the different boundary conditions. For the engineering purpose of sandwich panel design, the results are tabulated, which are calculated by using the nonlinear optimization technique SUMT.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.2
• /
• pp.19-27
• /
• 2007

The previous study was conducted to develop an air source multi heat pump system that could be operated with the solar collector and air source heat exchangers as heat source of the system. There is a winter-sowing problems in air source multi heat pump system when the outdoor temperature goes down under freezing point. The winter-sowing problem was solved by adapting R-22 refrigerant as working fluid in the previous study. However, when the system operated at high temperature, another problems are come out such as overheating of the solar collector outlet which lead to the superheat of the compressor inlet of the heat pump system. The condition could deteriorates a compressor in some case. In this study, we installed the anti-superheating devices on the previously developed system. As results of system performance test, COP of the system with anti-superheating technique is 2.4. It is a little improved COP compare to previous study's 2.23. In the results of multi heat source heating system, during operating solar collector, COP is relatively high between $200\;W/m^2$ and $400\;W/m^2$ solar intensity. It is recommended to extend the study on performance optimization with balancing the solar collect and capacity of compressor at higher solar irradiation conditions.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.10
• /
• pp.2253-2258
• /
• 2009

wet spun polyacrylonitrile (PAN) fiber precursors. The process variables chosen were treatment temperature, applied tension in stabilization process. The temperature profile of the stabilization was set on the basis of exothermic peaks of the differential scanning calorimetry (DSC) result. Both tensile strength and modulus increased with holding at onset temperatures of the exothermic peaks for extended duration, and with a higher heating rate up to the onset temperatures at a given applied tension among the experimental conditions. The increase in load monotonously increased the tensile modulus, on the other hand, the tensile strength was maximum at the load of 15 mg/filament (T15). The load 20 mg/ filament (T20) was considered to be exceeded to form oriented crystalline structure, possibly introducing more defects in the fiber than under load of T15. The sample CP3-T15 O5 H30 showed the best tensile properties among the samples experimented whose tensile properties are compatible with the commercialized grade of general purpose carbon fibers even at low carbonization temperature such as $800\;{^{\circ}C}$ (the carbonization temperature in the commercial process. 1300∼$1500\;{^{\circ}C}$).

• Journal of Ginseng Research
• /
• v.40 no.4
• /
• pp.453-461
• /
• 2016

Background: This study aims to describe the characterization of Paenibacillus polymyxa GBR-1 (GBR-1) with respect to its positive and negative effects on plants. Methods: The morphological characteristics of GBR-1 were identified with microscopy, and subjected to Biolog analysis for identification. Bacterial population and media optimization were determined by a growth curve. The potential for GBR-1 as a growth promoting agent, to have antagonistic activity, and to have hydrolytic activity at different temperatures was assessed. The coinoculation of GBR-1 with other microorganisms and its pathogenicity on various stored plants, including ginseng, were assessed. Results: Colony morphology, endospore-bearing cells, and cell division of GBR-1 were identified by microscopy; identification was performed by utilizing the Biolog system, gas chromatography of fatty acid methyl esters (GC-FAME). GBR-1 showed the strongest antagonistic activity against fungal and bacterial pathogens. GBR-1 cell numbers were relatively higher when the cells were cultured in brain heart infusion (BHI) medium when compared with other media. Furthermore, the starch-hydrolytic activity was influenced by GBR-1 at higher temperature compared to low temperatures. GBR-1 was pathogenic to some of the storage plants. Coinoculation of GBR-1 with other pathogens causes differences in rotting on ginseng roots. A significant growth promotion was observed in tobacco seedlings treated with GBR-1 suspensions under in vitro conditions, suggesting that its volatile organic compounds (VOCs) might play a role in growth promotion. Conclusion: The results of this study indicate that GBR-1 has both positive and negative effects on ginseng root and other stored plants as a potential biocontrol agent and eliciting in vitro growth promotion.