• Journal of the Korean Society of Food Culture
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• v.5 no.1
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• pp.169-180
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• 1990

An experimental study on the effect of milk diet on carcinogenesis induced by N-methyl-N-nitro-N-nitrosoguanidine (MNNG) was designed in rats to elucidate its mechanism. A total of 136 Sprague-Dawley rats were divided into 6 groups according to the milk dosagnes in each diet. The entire group of 136 rats was fed the MNNG (100 g/ml) and milk for the initial 28 weeks. Thereafter for the next 12 weeks the group was fed a normal diet only. After this 40 week experiment 109 rats survived. These rats were then dissected with the results being summarized as follows: Suppression of gastroduodenal malignancy was evidenced by the increase of milk concentration in the diet except for the group given MNNG and the lowest concentration of milk (6% milk). Significant differences in the rate of cancer association were present between the regenerative hyperplasia (22.2%) and adenomatous hyperplasia (57.9%). The incidence of benign lesions increased proportionally with the concentration of milk in the diet, especially in regenerative hyperplasia. In the group which had been given the lowest concentration of milk there was a significant increase of the serum gastrin level in the rats with gastric cancer or precancerous benign lesions like regenerative hyperplasia or adenomatous hyperplasia.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.169-175
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• 1998

Background: Heliox is known to decrease $PaCO_2$ in patients with increased airway resistance by increasing minute ventilation and reducing work of breathing(WOB). Besides these effect, heliox is expected to decrease functional anatomic dead space owing to improvement of peak expiratory flow rate(PEFR) and enhancement of gas distribution. We investigated whether heliox can decrease $PaCO_2$ even at the same minute ventilation (VE) and WOB with $N_2-O_2$ to speculate the effect of the heliox on the anatomic dead space. Material and Method: The subjects were 8 mechanically ventilated patients with asthma or upper airway obstruction(M : F=5 : 3, $68{\pm}10$years) who were under neuromuscular paralysis. The study was consisted of three 15-minutes phases: basal $N_2-O_2$ heliox and washout Heliox was administered via the low pressure inlet of servo 900C, and respiratory parameters were measured by pulmonary monitor(CP-100 pulmonary monitor, Bicore, Irvine, CA, USA). To obtain the same tidal volume(Vt) in heliox phase, the Vt on monitor was adjusted by the factor of relative flow rate of heliox to $N_2-O_2$. Dead space was calculated by Bohr equation. Results: 1) Vt, VE, peak inspiratory pressure(PIP) and peak inspiratory flow rate(PIFR) were not different between $N_2-O_2$ and heliox. 2) PEFR was higher on heliox($0.52{\pm}0.19$L/sec) than $N_2-O_2$($0.44{\pm}0.13$L/sec)(p=0.024). 3) $PaCO_2$(mmHg) were decreased with heliox($56.1{\pm}14.1$) compared to $N_2-O_2$($60.5{\pm}15.9$)(p=0.027). 4) Dead space ventilation(%) were decreased with heliox($73{\pm}9$ with $N_2-O_2$ and $71{\pm}10$ with heliox)(p=0.026). Conclusion: Heliox decreased $PaCO_2$ even at the same VE and WOB with $N_2-O_2$, and the effect was considered to be related with the reduction of anatomic dead space.

• Journal of Veterinary Clinics
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• v.32 no.4
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• pp.308-312
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• 2015

This study was aimed to evaluate the effects of tramadol hydrochloride on the minimum alveolar concentration of isoflurane ($MAC_{ISO}$) in dogs. Six healthy, female German shepherd dogs (aged 1-2 years) were used in this study. Anesthesia was induced by mask induction and maintained with isoflurane in oxygen. Mechanical ventilation maintained the end-tidal $CO_2$ partial pressure ($P_{ET}CO_2$) from 35 to 45 mmHg throughout the study. A baseline $MAC_{ISO}$ ($MAC_{ISO}B$) was determined starting 45 minutes after induction of anesthesia by clamping a pedal digit until gross purposeful movement was detected. After $MAC_{ISO}B$ determination, dogs received a tramadol loading dose of 3 mg/kg followed by a continuous rate infusion (CRI) of 2.6 mg/kg/h. The determination of $MAC_{ISO}$ after administration of tramadol ($MAC_{ISO}T$) began 20 min after the start of the CRI. Arterial blood pressure and heart rate were recorded continuously and arterial blood samples for blood gas analysis were collected at the end of the equilibration period. Mean ${\pm}$ SD values for the $MAC_{ISO}B$ and $MAC_{ISO}T$ were $1.33{\pm}0.04%$ and $1.23{\pm}0.04%$, respectively. The $MAC_{ISO}B$ decreased significantly by $7.5{\pm}0.2%$ (P < 0.05) after administration of tramadol. The mean heart rate and arterial blood pressure of six dogs were not changed significantly after tramadol administration. The blood gas levels remained constant during the study. In conclusion, tramadol could significantly reduce $MAC_{ISO}$ without depression of cardiorespiratory function. Thus, the use of tramadol on inhalation anesthesia with isoflurane in dogs can improve the stability of anesthesia and the quality of recovery.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.151-151
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• 2003

토양에 방치된 농업용 폐비닐은 거의 분해가 되지 않으며, 수분과 공기의 유통을 차단하고 토양 내 미생물들의 흐름을 막아 토양을 더욱 황폐화시키게 된다. 불법적인 소각 때는 산불의 위험에다 다이옥신, 염소 및 염화수소가스 등을 배출해 대기오염을 유발시킨다. 폐비닐을 열분해과정으로 처리하여 아주 작은 입자로 미분쇄하고 겔상태로 용융된 원료물질속으로 완전히 균일하게 혼합하여 골재로 활용하는 과정에서 가스상과 액상의 여러 가지 중간생성물질이 발생하게 되며, 농약의 살포에 의한 잔류농약 둥 인체에 유해가능한 요소들이 있을 수 있다. 본 연구에서는 개발공정이나 제품에서 인체에 영향을 미칠 수 있는 물질에 대하여 유해성을 평가하고 용응 겔 및 가스와 오일에 함유된 화학성분을 분석하였기에 보고하고자 한다 시험동물의 혈액생화학적 검사에서는 농업용 폐비닐물질 및 열분해 파생물질의 혈청 Cholesterol, 혈청 Alanine aminotranseferse와 Aspartate aminotransferse, Albumin 수치, LDH, Glucose, Uric acid, A/C 비 등의 생화학적 활성도를 측정한 결과들에서는 농업용 폐비닐물질을 투여한 시험군에서 나타난 결과와 비교하여 열분해 파생물질을 투여한 시험군에서 나타난 결과가 감소된 통계결과를 보였다. 이 결과들은 농업용 폐비닐물질을 투여한 시험군보다 열분해 파생물질을 투여한 시험군의 외부독성물질 투여에 의한 생체독성의 영향과 생체에 가해진 스트레스강도가 작았음을 의미하는 것이다. 잔류농약분석에서는 시료로부터 농약을 추출하는 용매추출과정, 시료추출물 중 공존하는 방해성분을 제거하는 정제과정, 폐비닐물질 및 열분해 파생물질 성분을 100mg/kg 이상군의 투여 후 시험동물의 부검시 모든 투여군에서 독성소견이 인정되지 않았다. 이와 같은 결과로 열분해 및 연소과정에서 발생하는 파생물질의 분석결과를 응용하여 대기오염을 방지하고 인체 유해물질을 차단하는 공해 방지 설계의 기초자료를 제안하고자 한다.

• Polymer(Korea)
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• v.35 no.5
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• pp.458-466
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• 2011

In the mixed system of supercritical carbon dioxide/organic solvents, poly(vinyl alcohol)(PVA) film of high degree of hydrolysis could be dyed with a dichroic dye of C. I. direct black 22(DB22) and as a result, high durability was obtained. Especially, as a dye dispersant in a supercritical fluid phase, a mixed solvent system of ethylene glycol: dimethyl sulfoxide=4 : 6 weight ratio was investigated. Then the optimum pressure for dyeing could be reduced down to 200 bar. Using this supercritical fluid system, the maximum dyeing appeared as the transmittance of less than 1% and the waste amount was reduced to the level of 1/10. After 500% drawing of this PVA film, both the polarizing efficiency of 94% and the single piece transmittance of 30% were obtained. The limitation of DB22 and further improvements were also discussed.

• Clean Technology
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• v.23 no.2
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• pp.140-147
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• 2017

In this study, we performed numerical simulation for the catalyst regeneration process of diesel desulfurization reactor. We analyzed the changes in regeneration process according to purge gas flow rate, catalyst permeability, reactor size, and heat loss of reactor. We have found that the regeneration process is very much affected by temperature changes whereas it is hardly affected by catalyst permeability and porosity. We also estimated the regeneration time according to purge gas flow rate and initial temperatures and have found that increasing purge gas temperature is more effect for fast regeneration. The present results can be utilized to design a regeneration process of diesel desulfurization reactor for a fuel cell used in ships. Furthermore, the present work also can be used to design low sulfur diesel supply in oil refineries and therefore contribute to the development of clean petrochemical technology.

• Membrane Journal
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• v.26 no.2
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• pp.141-145
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• 2016

Polymer electrolyte membranes (PEMs) are key components to determine electrochemical fuel cell performances, in addition to electrode materials. The PEMs need to satisfy selective transport behaviors to small molecules including gases and protons; the PEMs have to transport protons as fast as possible, while they should act as hydrogen barriers, since the permeated gas induces the thermal degradation of cathode catalyst, resulting in rapid electrochemical reduction. To date, limited tools have been used to measure how fast hydrogen gas permeates through PEMs (e.g., Constant volume/variable Pressure (time-lag) method). However, most of the measurements are conducted under vacuum where PEMs are fully dried. Otherwise, the obtained hydrogen permeance is easily changeable, which causes the measurement errors to be large. In this study, hydrogen permeation properties through Nafion212 used as a standard PEM are evaluated using an in-situ measurement system in which both temperature and humidity are controlled at the same time.

• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.7-16
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• 2024

This study presents investigation on the technical characteristics and field cases of the salt cavern storage method for large-scale hydrogen storage. The salt cavern storage method enables effective hydrogen storage compared to other methods due to the low porosity and permeability of the rock salt that constitutes the cavern, which is not likely to leak and requires a small amount of cushion gas for operation. In addition, there is no chemical reaction between rock salt and hydrogen, and multiple injection/withdrawl cycles can be performed making it effective for peak shaving and short-term storage. The salt cavern is formed in three stages: leaching, debrining, and filling, and leakage tests are conducted to ensure stable operation. Field applications are currently performing to meet industrial demand in the surrounding area of four sites in the UK and Texas, USA, and salt cavern operation is being prepared for energy storage in European countries such as Germany and France. The investigated results in this study can be utilized as a basic guideline for the design of future hydrogen storage projects.

• Clean Technology
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• v.9 no.4
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• pp.169-177
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• 2003

In order to develope a clean technology by liquid-supported membrane of ionic liquid/PVDF, the solubility of R22 and HFP gases using BMIBF4 as ionic liquid were measured at temperatures from 0 to $30^{\circ}C$, at total pressures up to 4 bars. The solubility of R22 in this ionic liquid was shown a rapid increasing tendency with increases of pressure and decreases of temperature, respectively, whereas the solubility of HFP was showed only a little in the same conditions. Based on these results, liquid-supported membranes of ionic liquid/PVDF were prepared by variables of the deposition amount of ionic liquid in polymer matrix, PVDF and were applied to the separation of fluoro-gases(R22, HFP) including $N_2$ gas. The permeability of R22 was rapidly increased by depending on the deposition amounts of ionic liquid, whereas both of HFP and $N_2$ were just showed so little. Especially, the diffusivity coefficient and solubility parameter of R22 were increased by lower operating temperatures and increased deposition amount of ionic liquid in 1iquid membrane. In conclusion, the selectivity of R22 against HFP was changed to 10-45 times depending on both of operating temperatures and the deposition amount of ionic liquid in BMIBF4/PVDF liquid membrane.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.407-411
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• 2015

Dense ceramic membranes have been prepared using the commercial perovsikite $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$, powders synthesized by the solid state reaction method. The as-synthesized powders were compressed into disks with 1.0 mm of thickness and the disk was sintered at $1,100^{\circ}C$ for 2 hr. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membrane increased with the increasing temperature and oxygen partial pressure. The activation energy for oxygen permeation was increased with the increasing oxygen partial pressure. Oxygen permeation flux at $950^{\circ}C$ were measured at various flow rates of feed and sweep gas. It has been demonstrated that oxygen permeability increased at elevated flow rates of both gases, but the sweep gas is more influential.