• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.2
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• pp.187-207
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• 2019

In order to develop a high performance ocean model, we used Julia, a Just-In-Time compile language, and to obtain the solution of the momentum equation, we made the code to solve the Poisson equation by the Successive Over-Relaxation method. And then we made two models to test Julia calculation codes. First, a simple channel form is modeled to test constant source/sink conditions. Second, the simplified Yellow Sea was modeled to test tidal forcing, Coriolis forces, and the effect of vertical eddy diffusivity coefficients. The model has been tested with a total of eight cases in the two scenarios. As a result of the test, the depth-averaged current speed of the three cases in Scenario 1 converged perfectly to the theoretical value, and that showed well a vertical flow velocity gradient due to the bottom friction. Also, the result of Scenario 2 represented well the amphidromic points of Yellow Sea and the tidal characteristics of mid-western and southwestern coast of Korea. Therefore, it is considered that the ocean model using Julia language has developed successfully, this suggests that the ocean model has come to the stage of successful transition from a classical compile language to a Just-In-Time compile language.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.2
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• pp.64-72
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• 1989

A response prediction model is introduced for the non-lockin vibration of a marine riser in sheared flow, where the riser is modelled as linearly varying tensioned-beam. This prediction model is based on the Green's function approach and random vibration theory. This model, of course, can treat general beams having slowly varying spatial system parameters. According to the predicted result of a marine riser by the prediction model proposed in this paper, the dynamic behavior of a marine riser has the mixed characteristics of finite and infinite boundary behavior. Furthermore the velocity response distribution along the riser length is much similar with the sheared flow profile. The predicted response result of a marine riser having linearly varying tension was also compared to that of constant mean tensioned-beam model. It was found that the constant mean tensioned-beam case gives over-estimated responses at the top side of the riser.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.11
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• pp.1055-1063
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• 2012

Fluctuating wall pressures were measured using an array of 16 piezoelectric transducers beneath a turbulent boundary layer. The coating used in this experiment was an open-cell, urethane-type foam with a porosity of approximately 50 ppi. The ultimate objective of the coating is to provide a mechanical filter to reduce the wall pressure fluctuations. The boundary layer on the flat plate was measured by using a hot wire probe, and the CPM method was used to determine the skin friction coefficient. The wall pressure autospectra and streamwise wavenumber-frequency spectra were compared to assess the attenuation of the wall pressure field by the coating. The coating is shown to attenuate the convective wall pressure energy. However, the relatively rough surface of the coating in this investigation resulted in a higher mean wall shear stress, thicker boundary layer, and higher low-frequency wall pressure spectral levels compared to a smooth wall.

• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.288-299
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• 1996

This is the basic study to investigate the amount of transpirational water loss in thrifty mature Quercus mongolica stand by the heat pulse method. The differences of heat pulse velocity by direction and depth, differences of heat pulse velocity by dominant, codominant and suppressed trees, diurnal changes of heat pulse velocity due to the change of leaf water potential, vapor pressure deficit and radiation, and sap flow path way in sapwood by dye penetration were measured in stems. Finally the amounts of daily and annual transpiration in stand were calculated by the heat pulse velocity. The results obtained were summarized as follows : 1. Relationship between heat pulse velocity(V) and sap flow rate(SFR) was obtained as a equation of SFR=1.37V. 2. The sap flow rate was high in the order of dominant, codominant, and suppressed trees. The daily heat pulse velocity changed with radiation, temperature and vapor pressure deficit. 3. The heat pulse velocity showed the similar diurnal variation as the leaf water potential change. 4. The heat pulse velocity showed the highest value in May(4.0cm/hr in average), the lowest one in July(2.9cm/hr in average). 5. The heat pulse velocity in the same stem presented the highest value in the northern direction, medium in western, and the lowest in southern and eastern. 6. The heat pulse velocity in stem was highest in 0.5cm, medium in 1.0cm, and lowest in 1.5cm depth from the surface of stem. 7. The sap flow path way in stem showed sectorial straight ascent pattern in four sample trees. 8. The amount of sap flow(SF) was presented as a equation of $SF=1.37A{\cdot}V$(A: the cross-sectional area of sapwood, V: heat pulse velocity), and especially SF was larger in dominant tree than codominant and suppressed trees. 9. The amount of daily transpiration was 5.6ton/ha/day, and its composition ratio was 72% at day and 28% at night. 10. The amount of stand transpiration per month was largest in May(168ton/ha/month), lowest in July(125ton/ha/month). The amount of stand transpiration per year was 839ton/ha/year.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5578-5586
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• 2012

The accurate estimation of discharge is very essential as the important factor of river design for the utilization and flood control, hydraulic construction design. The present discharge production is using the stage-discharge relationship curve in the river. The rating curve uses the method by predicting the discharge based on regression analysis using the measured stage and discharge data in a flood season. The method is comparatively convenient and has especially advantages in that it can predict the discharge having the difficulty of observation in a flood season. However, this method has basically room for improvement because the method only uses the relationship between stage and discharge, and doesn't reflect the hydraulic parameters such as hydraulic radius, energy slope, roughness, topography, etc.. Therefore, in this study, discharge was predicted using the convenient calculation method with empirical parameters of the Manning and Chezy equations, which were proposed by Choo et at (2011) in KSCE as a new methodology for estimating discharge in open channel. The proposed method can conveniently estimate empirical parameters in both of Manning and Chezy equations and the discharge is estimated in the open channels. There are proved by using data measured in meandering lab. channel and India canal and the accuracies show about determination coefficient 0.8. Accordingly, this method will be used in actual field if this study is continuously conducted.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.141-141
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• 2003

신선농산물의 호홉속도를 측정하는 방법 중 하나인 개방계(open system) 호흡속도 측정시스템은 소정의 농도로 조정된 혼합기체를 측정대상시료에 흘려 보내며 측정하는 방법이다. 개방계 측정법의 장점은 혼합 기체조성 영역에서 정확한 호흡속도를 얻을 수 있으며 방치시간이 필요 없으므로 반복 측정이 용이한 것 등이다. 그러나 개방계 측정법은 공급되는 혼합기체의 농도와 유속이 일정하여야 하며 연속으로 호흡속도 측정용 챔버의 혼합기체 공급측과 배기측에서 기체시료를 수집하여 매우 미세한 기체농도의 차이를 측정할 수 있어야 하고 기체 시료 수집에 상당한 주의가 요구된다. 이러한 문제를 개선하기 위하여 개방계 호흡속도 측정 시스템을 자동화하였다. 자동화된 호흡속도 측정 시스템은 혼합기체 발생장치, 온도조절이 가능한 기체기밀용 챔버와 G.C로 구성되어 있다. 환경기체조성을 위한 혼합기체발생장치는 $N_2$, $O_2$, $CO_2$ 압축 실린더에서 공급되는 기체를 압력 조절기를 통해서 일차압력을 조정하고 정밀 압력 조절기를 이용하여 0.1~0.2 kg/$\textrm{cm}^2$의 정압을 유지시켰다. 압력이 일정해진 기체는 metering valve를 이용하여 각 기체의 유량을 소정의 비율로 제어할 수 있도록 하였으며 각각의 기체는 gas mixed cell에서 실험 농도의 환경기체조성으로 혼합되어 항온기내의 호흡속도 측정 챔버($25^{\circ}C$)로 공급될 수 있도록 하였다. 호흡속도 측정용 챔버는 개스킷이 장착된 아크릴 재질이며 온도 조절이 가능한 항온기로 구성되어 있다. 호흡속도 측정용 챔버와 G.C간의 기체흐름은 three way solenoid valve에 의하여 제어되며 전원의 on/off에 따라 공급측의 가스와 배기측의 가스가 선택적으로 G.C에 공급될 수 있도록 구성하였다. 측정 대상 챔버의 기체는 제어된 유로를 따라 multi-position valve를 통과하여 G.C에서 분석되도록 하였다. 본 연구에서 개발된 개방계 호흡속도 자동 측정 시스템의 성능 실험에서 혼합기체발생장치에서 조제된 혼합 기체의 농도를 설정치와 비교한 결과 $O_2$와 $CO_2$의 농도에서 평균오차 0.2%로 정밀한 것으로 나타났으며 호흡속도 측정용 챔버의 혼합기체 공급측과 배기측의 가스 농도를 3회 반복 측정한 결과 재현성에서는 0.1%이하의 편차로 나타났다. 개방계 호흡속도 자동 측정 시스템을 이용하여 환경기체조성하에서 토마토의 호흡속도를 측정하는 실측 실험을 수행한 결과 2$0^{\circ}C$에서 12.7~42.1mg$CO_2$/kg.hr였으며 12$^{\circ}C$에서 2.5~8.2mg$CO_2$/kg.hr로 일반적으로 보고되고 있는 토마토 호흡속도와 일치하는 결과를 나타내었다.

• Analytical Science and Technology
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• v.20 no.4
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• pp.347-354
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• 2007

A simple and rapid high-performance liquid chromatography assay for the determination of residual novobiocin levels in bovine, porcine, chicken, flatfish and japanese eel muscle has been developed and validated. The separation condition for HPLC/UV was optimized with phenyl hexyl ($4.6{\times}150mm$, $5{\mu}m$) column with 10 mM monobasic sodium phosphate buffer (pH 2.5)/acetonitrile (50/50, v/v) as the mobile phase at a flow rate of 1.0 mL/min and detection wavelength was set at 254 nm. Residues were extracted from tissue by blending with methanol and lipid materials were removed with n-hexane. Then, the methanol extract was evaporated to dryness under a nitrogen stream, reconstituted in the mobile phase. Aliquot of the organic extract was decanted and filtered through $0.45{\mu}m$ syringe filter. The $20{\mu}L$ of the resulting solution was injected into the HPLC system. The calibration ranges were $0.5{\sim}5{\mu}g/g$ and calibration curves were linear with coefficients of correlation better than 0.95. The limits of quantification were $0.5{\mu}g/g$ for all muscles. The recoveries of bovine, porcine, chicken, flatfish and japaneseel muscles were 99.8%, 102.4%, 91.0%, 104.0% and 93.0%, respectively. The procedures were validated according to the CODEX guideline, determining specificity, linearity, accuracy, precision, quantitation limit and recovery.

• Journal of Chest Surgery
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• v.30 no.5
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• pp.471-478
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• 1997

Introduction: The use of rabbits as a cardiopulmonary bypass(CPB) animal model is extremely dif%cult mainly due to technical problems. On the other hand, deep hypothermic circulatory arrest(CA) is used to facilitate surgical repair in a variety of cardiac diseases. Although steroids are generally known to be effective in the treatment of cerebral edema, the protective effects of steroids on the brain during CA are not conclusively established. Objectives of this study are twofold: the establishment of CPB technique in rabbits and the evaluation of preventive effect of steroid on the development of brain edema during CA. Material '||'&'||' Methods: Fifteen New Zealan white rabbits(average body weight 3.5kg) were divided into three experimental groups; control CA group(n=5), CA with Trendelenberg position group(n=5), and CA with Trendelenberg position + steroid(methylprednisolone 30 mglkg) administration group(n=5). After anesthetic induction and tracheostomy, a median sternotomy was performed. An aortic cannula(3.3mm) and a venous ncannula(14 Fr) were inserted, respectively in the ascending aorta and the right atrium. The CPB circuit consisted of a roller pump and a bubble oxygenator. Priming volume of the circuit was approximately 450m1 with 120" 150ml of blood. CPB was initiated at a flow rate of 80~85ml/kg/min, Ten min after the start of CPB, CA was established with duration of 40min at $20^{\circ}C$ of rectal temperature. After CA, CPB was restarted with 20min period of rewarming. Ten min after weaning, the animal was sacrif;cod. One-to-2g portions of the following tissues were rapidly d:ssected and water contents were examined and compared among gr ups: brain, cervical spinal cord, kidney, duodenum, lung, heart, liver, spleen, pancreas. stomach. Statistical significances were analyzed by Kruskal-Wallis nonparametric test. Results: CPB with CA was successfully performed in all cases. Flow rate of 60-100 mlfkgfmin was able to be maintained throughout CPB. During CPB, no significant metabolic acidosis was detected and aortic pressure ranged between 35-55 mmHg. After weaning from CPB, all hearts resumed normal beating spontaneously. There were no statistically significant differences in the water contents of tissues including brain among the three experimental groups. Conclusion: These results indicate (1) CPB can be reliably administered in rabbits if proper technique is used, (2) the effect of steroid on the protection of brain edema related to Trendelenburg position during CA is not established within the scope of this experiment.

• Tuberculosis and Respiratory Diseases
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• v.54 no.4
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• pp.386-394
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• 2003

Background : ATS(American Thoracic Society) defined new guidelines for COPD(chronic obstructive lung disease) in April 2001, following the results of the global initiative for chronic obstructive lung disease. The most important concept of COPD is an airflow limitation which is not fully reversible compared to bronchial asthma(BA). The criteria for COPD are postbronchodilator $FEV_1$ less than 80% of the predicted value and an $FEV_1$ per FVC ratio less than 70%. The global initiative for asthma(GINA) study defined asthma, which included immune-mediated chronic airway inflammatory airway disease, and found that airflow limitation was wide spread, variable and often completely reversible. Taken together COPD and BA may be combined in airflow limitation. This study was designed to evaluate the prevalence of BA in patients with COPD of moderate to severe airflow limitation. Methods : COPD was diagnosed by symptoms and spirometry according to ATS guidelines. Enrolled subjects were examined for peak flow meters(PFM), sputum eosinophils and eosinophil cationic protein(ECP) levels, serum total IgE with allergy skin prick test, and methacholine bronchial provocation test(MBPT). Results : About 27% of COPD patients with moderate to severe airflow limitation were combined with BA. There was significantly decreased response to PFM in severe COPD. However, there was no significant relationship between BA and COPD according to the degree of severity. The BA combined with COPD group showed significantly high eosinophil counts and ECP level in induced sputum. However, neutrophil counts in induced sputum showed significant elevation in the pure COPD group. Conclusion : Twenty-seven percent of COPD patients with moderate to severe ventilation disorder were combined with BA, but there were no significant differences according to the degree of severity.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.217-229
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• 2000

Adsorption equilibrium experiments for the phenol on granular activated carbon(16~25 mesh) and powder activated carbon(325 mesh) were carried out at $25{\pm}1^{\circ}C$ and the results were expressed with Freundlich isotherm. Adsorption rate experiments were executed in batch adsorption system under the condition that can be neglecting mass transfer resistance at the external surface of the particle. The results were analysed with the Miller's method to evaluate the linear driving force(LDF) adsorption rate constant. Fixed bed adsorption experiments were performed by adopting different flow rates in the activated carbon-phenol system at $25{\pm}1^{\circ}C$. The theoretical breakthrough curves were estimated with the simple constant pattern solution. The adsorption rate constant of LDF model was not a fixed value but variable with adsorption amount. The experimental results were better agreed with the estimation of breakthrough curve using the variable adsorption rate constant than the results estimated using the average fixed adsorption rate constant.