• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.344-347
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• 2006

Noise reduction and control is an important problem in the performance of underwater acoustic system and on the habitability of the passenger ship for crew and passenger. Furthermore, sound generated by a propeller is critical in underwater detection and is often related to the survivability of the vessel especially for military purpose. Generally propeller noise is often the dominant noise source of marine vehicle. The flow field is analyzed with potential-based panel method, and then the time dependent pressure and sheet cavity volume data are used as the input for Ffowcs Williams-Hawkings formulation to predict the far-field acoustics. Through this study, the dominant noise source of underwater propeller is analyzed, which will provide a basis for proper noise control strategies.

• Analytical Science and Technology
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• v.8 no.4
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• pp.787-792
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• 1995

A method for determination of ammonia-N in environmental water by air-segmented flow injection analysis using the colour reaction of phenol and sodium hypochlorite with ammonia was described in this paper. When the reaction temperature is $70^{\circ}C$ and the reaction residence time is 5 minutes, a sample frequency of $60-90h^{-1}$ can be achieved. The detection limit and relative deviation are $0.05mg.ml^{-1}$ and 4%, respectively. The recovery of this method is 96 - 110%, and the determination results of the method are greatly agreement with standard colorimetric method.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1230-1232
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• 2010

A simple, rapid and validated reverse d phase liquid chromatographic method has been developed for the determination of Letrozole (LZ) in pharmaceutical dosage. LZ was separated on ODS analytical column with a mixture of acetonitrile, water in the ratio 50:50 (v/v) as mobile phase at a flow rate of 1.0 mL /min. The effluent was monitored by UV detection at 265nm. Calibration plot was linear in the range of 160 to $240{\mu}g$/mL with the linear regression (r) = 0.999. The method was validated for recovery, precision, specificity.

• Journal of Environmental Impact Assessment
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• v.20 no.2
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• pp.199-205
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• 2011

The Saemangeum embankment construction have changed the flowing on the topography of the coastal marine environment. However, the variety of ecological factors are changing from outside of Saemangeum embankment area. The ecosystem of various marine organisms have led to changes by sea surface temperature. The aim of this study is to monitoring of sea surface temperature(SST) changes were measured by using thermal infrared satellite imagery, MODIS and Landsat. The MODIS data have the high temporal resolution and Landsat satellite data with high spatial resolution was used for time series monitoring. The extracted informations from sea surface temperature changes were compared with the dyke to allow them inside and outside of Saemangeum embankment. The spatial extent of the spread of sea water were analyzed by SST using MODIS and Landsat thermal channel data. The difference of sea surface temperature between inland and offshore waters of Saemangeum embankment have changed by seasonal flow and residence time of sea water in dyke.

• The Korean Journal of Food And Nutrition
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• v.6 no.3
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• pp.219-230
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• 1993

This research aims to study the changes In gastrointestinal function attributed to aging In human. The thresholds for recognition and detection of flavors became elevated and salivary gland acinar cells decreased in the old age. But most esophageal function remained relatively Intact. Although gastric emptying time has been slowed with aging, the total intestinal transit time did not differ. Atropic gastritis due to H. pylori in old man decreased secretion of acid and Intrinsic factor and absorbability of calcium and iron. Pancreatic secretion is droned in older persons. Prevalence of gallstones rised with age. Liver size and portal blood flow decreased significantly with age. Mucosal surface area has been reported to be slightly diminished in the aging man. Glucose transporters decreased and Insulin tolerance Increased. Absorption of aromatic amino acid is diminished with age. Dietary protein In that aging human increased fecal nitrogen excretion. Vitamin A tolerance increased. Vitamin D receptor concentration decreased and resistance to 1,25-(OH)2D3 action increased. Permeability of aging small Intestine Increased. Zinc balance dirt not differ Copper absorption appeared not to be significantly affected by age. Neurotensin secretion decreased thus slowed colonic peristaltic movements and Intestinal mucosal growth.

• Herbal Formula Science
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• v.18 no.2
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• pp.251-257
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• 2010

Objectives : To develop and validate High-performance liquid chromatography-photodiode array methods for simultaneous determination of two constituents in Oryeong-san(ORS). Methods : Reverse-phase chromatography using a Gemini C18 column operating at $40^{\circ}C$, and photodiode array(PDA) detection at 280 nm, were used for quantification of the two marker components of ORS. The mobile phase using a gradient flow consisted of two solvent systems. Solvent A was $H_2O$ and solvent B was acetonitrile. Results : Calibration curves were acquired with correlation coefficient ($r^2$)>0.9999, and the relative standard deviation(RSD) values(%) for intra- and inter-day precision were not exceed 1.0%. The recovery rate of each compound was in the range of 93.01-104.16%, with an RSD less than 2.0%. The contents of two compounds in ORS were 1.10-3.72 mg/g. Conclusions : The established HPLC method will be helpful to improve quality control of ORS.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.521-525
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• 2014

Circulating tumor cells (CTCs) in the bloodstream of cancer patients provide an accessible source for detection, characterization, and monitoring of nonhematological cancers. The effectiveness of the CTC-Chip for the isolation of ovarian cancer cells was demonstrated by adapting the herringbone-chip (HB-Chip). The motions of the particles on the HB chip were simulated by a unique combination of buoyant, gravitational forces, and helical flows with a computational modeling. The motions of cells are demonstrated by applying polystylene bead and ovarian cancer cells into the microfabricated HB-Chip. The experimental results from beads and cells are well accordance with the simulated ones, as previously reported by Toner group. Thus, I expect that these modeling and experimental skills will play key roles in the clinical applications on CTC isolation as well as the basic research on characterization of CTCs under flow.

• Korean Journal of Bronchoesophagology
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• v.1 no.1
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• pp.75-81
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• 1995

To evaluate the diagnostic value of pulmonary perfusion scan, we obtained 99mTc MAA per-fusion lung scan from 25 cases of airway foreign bodies. The results were as follows. 1) Significant changes in blood gases were not observed after the establishment of regional hypoperfusion caused by airway foreign body. 2) Near total or total defect was noted on perfusion scan from most of the airway foreign body. 3) There was correspondance of findings of perfusion lung scan and duration of airway foreign body. 4) After the removal of airway foreign bodies, perfusion scan abnormalities were reversed in parallel with the recovery of pulmonary blood flow. We concluded that pulmonary perfusion scan may be valuable for detection of foreign body and reversible hypoperfusion.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.12
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• pp.8-14
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• 2015

An effective way to ensure that LEDs produce wanted light output is to use a current driving topology, because the brightness of LEDs is directly related to their current. However, this topology may lead to the lifetime shortening of a illumination system because over-currents may flow through non-damaged LEDs in case some LEDs are damaged. This paper presents an adaptive current control circuits for LEDs, which protect LEDs in a good state by limiting the driving currents according to the number of damaged ones. The proposed control circuits consist of a simple constant-current driver and a micro-controller which monitors the voltage of LED array without any auxiliary current sensors for fault diagnosis. And the driving current is automatically controlled into 6-levels according to the number of failures.

• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.800-804
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• 2007

Cyanobacterial toxins, microcystins are very potent hepatotoxins and their occurrence has been reported all over the world. They could threaten human health when toxic Microcystis occurs in water supply reservoirs. In this study, the effects of several environmental factors on production and degradation of toxins produced by cyanobacteria in Lake Soyang have been studied. A new rapid quantification method of microcystins using fluorescence for a detection signal and a lateral-flow-type immunochromatography as a separation system was used. Culture age, temperature, light intensity, pH, N-nutrient concentration, P-nutrient concentration, iron and zinc concentration were the most importantly examined factors. The toxin content was the highest on 17-18 days and at temperatures between 20℃ and 25℃, and at pH between 8.4 and 8.8.