• Fire Science and Engineering
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• v.27 no.3
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• pp.20-29
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• 2013

To investigate numerically the effects of geometry and location of vertical opening on the thermal and chemical fire characteristics in full-scale under-ventilated compartment fires, the ventilation factor ($A\sqrt{h}$) to estimate a theoretical maximum inflow of ambient air and the mass loss rate in a heptane pool fire were fixed for all cases. It was shown that variations in door geometry affected significantly the change in thermal and chemical characteristics inside the compartment. Variations in window location resulted in the complex change in additional fire characteristics including the fire duration time and recirculating flow structure. These results were analyzed in details by the multi-dimensional flow and fire characteristics including the vent flow and fuel/air mixing phenomena.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.89-95
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• 2017

The improvement of a flow coefficient for the recirculation chill-down flow in a main oxidizer shut-off valve has been presented. The flow coefficient, which is mainly affected by the recirculation outlet port size and the configuration inside the valve, has been predicted with measured flow coefficient values. The comparison of experimentally measured flow coefficient with the predicted value shows the effect of valve inside configuration on the flow coefficient. Consequently, the flow coefficient is twice the previous value and about 75% of the pressure loss assigned to the main oxidizer shut-off valve can be used for additional pressure losses for other components in the recirculation chill-down system of a launch vehicle.

• Solar Energy
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• v.19 no.3
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• pp.29-41
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• 1999

Three-dimensional natural convective heat transfer in a vertical channel with a protruding single module was investigated experimentally. The particular interest was in the removal of thermal energy from the module by convective heat transfer. Hence radiative and conductive heat losses were estimated by using thermocouples and heat flux sensor respectively. The flow fields in the channel were visualized by means of a smoke-method. Also, local temperatures were measured by thermocouples inside the channel, along the vertical wall and module surface. It is found that convective heat transfer was promoted at the lower comer of the module and was decreased at the upper comer due to a recirculation zone. A general correlation of the critical channel ratios was found as a function of Rayleigh number. For the range of $8.28{\times}10^3<Ra^*_c<3.48{\times}10^6$, a useful correlation for the mean Nusselt number was proposed as a function of modified channel Rayleigh number.

• Journal of Navigation and Port Research
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• v.38 no.5
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• pp.451-456
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• 2014

Lab scale experiment was carried out to study biological wastewater treatment technology developed for shipboard. RCM process using BM(Beneficial Microorganisms) was investigated for practical application on shipboard sewage treatment. RCM process is an environmental friendly treatment system, with minimum production of sludge. In the test, BOD5, CODcr, T-N and T-P were reduced a 96%, 97%, 78% and 81.68% respectively. From the result it was suggested that RCM process with BM might be a suitable process for shipboard sewage treatment, maintenance of useful microorganisms and creating special environment as the SDC tank is circulating in the non-biodegradable organics sludge generated during the wastewater treatment, thus reducing the amount of sludge generated. Therefore, the RCM process does not require additional equipment to strengthen it to meet the marine pollution standards.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.501-501
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• 2022

2014년 개정된 물의 재이용 촉진 및 지원에 관한법률(이하, 물재이용법)에 따라서 빗물이용시설의 수는 꾸준히 증가하고 있는 추세이나 실제 연간사용량의 경우 연별 증가량은 미미하다. 또한 2016년도 환경부 하수도 통계에 따른 2,043개의 빗물이용시설 중 집수면적 미파악시설의 749개, 여과시설 유무 미파악시설 564개, 연간 운영비 산출 불가능 시설 1,843개, 연강 사용량 미집계 시설 905개로 관리실태가 부실함을 확인할 수 있다. 이에 빗물이용시설의 설치·운영 실태조사 및 문제점을 분석하고 빗물이용이 비교적 활성화 된 시설을 대상은 현장조사를 수행을 통해 빗물이용시설의 현황을 분석하고 현실적인 여건을 반영하여 빗물이용을 활성화할 수 있는 방안을 마련하고자 하였다. 물재이용법에 따른 빗물이용시설 법정의무대상시설의 빗물활용처는 전체의 약 92%가 조경요수로 활용하고 있으며, 다음으로 청소화장실용수(약 3%)로 활용하고 있다. 건축물 용도에 따라서 골프장, 공공기관청사/공공업무시설, 대규모점포, 실내체육관/종합운동장, 학교의 경우 건축물 용도별로 각 30% 정도가, 공동주택의 경우 약 60%가 빗물이용시설을 활용하고 있음에도 빗물을 사용하지 았는 것으로 파악되었다. 이는 빗물을 사용해야하는 시기에 저류조에 저류된 빗물의 양이 부족한 것과 운영비 부담 순으로 조사되었다. 따라서 빗물이용시설의 빗물이용활성화를 위해서는 물수요-공급에 대한 개념을 도입한 물수지 분석이 필요하며, 운영비 부담을 줄일 수 있는 다양한 방안을 탐색하는 것이 적절할 것이다. 현장조사 결과에서도 기술 등의 발달로 빗물이용시설은 잘 구축되고 있으나 활용처에서 필요한 필요수량에 따라 활용률이 상이한 것으로 조사되었다. 이러한 실태조사 및 현장조사를 바탕으로 빗물이용시설의 빗물이용 활성화를 위한 방안에 대하여 기술적 및 제도적 방안에 대해서 제안하였다.

• Journal of Chest Surgery
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• v.37 no.2
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• pp.119-130
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• 2004

Decrease in cardiac function after open heart surgery is due to an ischemia induced myocardial damage during surgery, and ischemic preconditioning, a condition in which the myocardial damage does not accumulate after repeated episodes of ischemia but protects itself from damage after prolonged ischemia due to myocytes tolerating the ischemia, is known to diminish myocardial damage, which also helps the recovery of myocardium after reperfusion, and decreases incidences of arrythmia. Our study is performed to display the ischemic preconditioning and show the myocardial protective effect by applying cardioplegic solution to the heart removed from rat. Material and Method: Sprague-Dawley male rats were used, They were fixed on a modified isolated working heart model after cannulation. The reperfusion process was according to non-working and working heart methods and the working method was executed for 20 minutes in which the heart rate, aortic pressure, aortic flow and coronary flow were measured and recorded. The control group is the group which the extracted heart was fixed on the isolated working heart model, recovered by reperfusion 60 minutes after infusion and preserved in the cardioplegic solution 20 minutes after the working heart perfusion and aortic cross clamp, The thesis groups were divided into group I, which ischemic hearts that were hypoxia induced were perfused by cardioplegic solution and preserved for 60 minutes; group II, the cardioplegic solution was infused 45 seconds (II-1), 1 minutes (II-2), 3 minutes (II-3), after the ischemia induction, 20 minutes after working heart perfusion and aortic cross clamp; and group III, hearts were executed on working heart perfusion for 20 minutes and aortic cross clamp was performed for 45 seconds (III-1), 1minute (III-2), 3 minutes (III-3), reperfused for 2 minutes to recover the heart, and then aortic cross clamping was repeated for reperfusion, all the groups were compared based on hemodynamic performance after reperfusion of the heart after preservation for 60 minutes. Result: The recovery time until spontaneous heart beat was longer in groups I, II-3, III-2 and III-3 to control group (p<0.01). Group III-1 (p<0.05) had better results in terms of recovery in number of heart rates compared to control group, and recovered better compared to II-1 (p<0.05). The recovery of aortic blood pressure favored group III-1 (p<0.05) and had better outcomes compared with II-1 (p<0.01). Group III-1 also showed best results in terms of cardiac output (p<0.05) and group III-2 was better compared to II-2 (p<0.05). Group I (p<0.01) and II-3 (p<0.05) showed more cardiac edema than control group. Conclusion: When the effects of other organs are dismissed, protecting the heart by infusion of cardioplegic solution after enforcing ischemia for a short period of time before the onset of abnormal heart beats for preconditioning has a better recovery effect in the cardioplegic group with preconditioning compared to the cardioplegic solution itself. we believe that further study is needed to find a more effective method of preconditioning.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.177-184
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• 2012

This experiment was carried out to investigate soil properties and the requirement of livestock manure compost in a large-scale environment-friendly agricultural complex (EFAC), Gosan, Wanju-gun, Jeonbuk. Total cultivation area of major crops was 2,353 ha. This complex area included different types of environment-friendly cropping sections (402.9ha) and livestock farming including 21,077 Korean beef cattle, 1,099 dairy cow, and 32,993 hog. Amount of livestock waste carried in to Resource Center for Crop and Livestock Farming (RCCLF) was 32 Mg per day and the production of manure compost was 9,600 Mg per year. The manure contained 1.4% total nitrogen (T-N), 2.7% phosphorus as $P_2O_5$, 2.1% potassium as $K_2O$, 0.9% magnesium as MgO, 2.5% calcium as CaO. Amount of compost used in the EFAC was 6,588 Mg per year. Soil pH values in the EFAC were varied as follows: 78.1% of paddy field soil, 58.2% of upland soil, 60.3% of orchard field soil, and 62.1% of greenhouse soil were in proper range. For the content of soil organic matter, 41.7% of paddy field soil, 46.5% of upland soil, 40.5% of orchard field soil, and 81.4% of greenhouse soil were higher than proper range. The content of available phosphorus was mostly higher than proper value on the different fields except upland soil. The contents of exchangeable $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were also exceeded in the orchard field and greenhouse soils. In addition, microbial population, especially aerobic bacteria, in the EFAC was higher than that in regular farming land.

• 한국해양학회지
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• v.21 no.1
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• pp.13-24
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• 1986

The daily net primary production by phytoplankton in the southeastern sea of Korea in October 1985 ranged from 0.7 to 2.7 gCm$\^$-2/ d$\^$-1/ and averaged to be 1.3 gCm$\^$-2/ d$\^$-1/. Surface total chlorophyll ranged from 0.97 to 3.59mg chlm$\^$-3/. Primary production by nano-phytoplankton(〈20$\mu\textrm{m}$) ranged from 43 to 97% in the surface layer. Optimum light intensity(Iopt)was around 300 to 700${\mu}$Es$\^$-1/m$\^$-1/. Surface primary production from 9:00 to 15:00 h was evidently inhibited by strong light intensity beyond the Iopt. Phytoplankton near the base of euphotic zone(30-40m) showed extremely low Iopt suggesting adaptation to a low light environment. Since Iopt represents the history of light experience of phytoplankton at a given depth, the extent of variation in I of phytoplankton at different depth seems to be related to the in tensity of turbulence mixing in the surface mixed layer. From the present study, ammonium excretion by macrozooplankton (〉350$\mu\textrm{m}$) contributes from 3 to 19% of daily total nitrogen requirement by phytoplandton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer, based on the simple diffusion model, approximates 3% of nitrogen requirement by phytoplankton. However, large portion of nitrogen requirement by phytoplankton remains unexplained in this area. In upwelling area near the coast, adjective flux might be the major source for the nitrogen requirement by phytoplankton. This study suggests that the major nitrogen source for the phytoplankton growth might come from the pelagic regeneration by nano-and micro-sized heterotrophic plandkon. Enhancement of primary production during the passage of the warm Tsushima Current is discussed in relation with nutrient dynamics and hydrlgraphic processes in this area.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.681-697
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• 1994

The enzymatic hydrolysate of gelatin extracted from fish skin was fractionated and recycled through the membrane reactor according to the molecular weight for the purpose of using as functional material. In addition, the enzymatic hydrolysis conditions of gelatin, enzyme stability by membrane and mechanical shear, and effect on the long-term operational stability of the recycle membrane reactor were investigated. Using the pH-drop technique, Alcalase, pronase E and collagenase were identified as the most suitable enzymes for the hydrolysis of fish skin gelatin. The optimum hydrolysis conditions in the 1st-step membrane reactor(1st-SMR) by Alcalase were enzyme concentration 0.2mg/ml, substrate-to-enzyme ratio(S/E) 50(w/w), $50^{\circ}C$, pH 8.0, reaction volume 600ml and flow rate 6.14ml/min. In the 2nd-SMR by pronase E were enzyme concentration 0.3mg/ml, S/E 33(w/w), $50^{\circ}C$, pH 8.0, reaction volume 600ml and flow rate 6.14ml/min. In the case of 3rd-SMR, enzyme concentration 0.1mg/ml, S/E 100(w/w), $37^{\circ}C$, pH 7.5, reaction volume 600ml and flow rate 10ml/min. Decreased enzyme activities by mechanical shear and membrane were 30% and 15% in the 1st-SMR, were 14% and 5% in the 2nd-SMR, and 18% and 8% in the 3rd-SMR, respectively. Under the optimum conditions, the degree of hydrolysis in the 1st, 2nd and 3rd-SMR were 3.5%(Kjeldahl method, 87%), 3.1%(77%) and 2.7%(70%), respectively. The productivity of hydrolysate in the continuous three-step membrane reactor was 430mg per enzyme(mg) for 10 times of volume replacements.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.127-137
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• 2021

Air emission charge for nitrogen oxide as a precursor of fine dust has been introduced and implemented within the country from 2020. Therefore, the development of economical combustion technology for NOx reduction has got more needed urgently. This study investigated the air-staging effect as a way to reduce the NOx during combustion of domestic unused forest biomass, recently possible to secure REC (Renewable Energy Certification) as a substitute for overseas wood pellets in a 0.1 MWth circulating fluidized bed combustion test-rig. Operating conditions were comparison with and without air-staging, the supply position of tertiary air (6.4 m, 8.1 m, 9.4 m in the combustor) and variation of air-staging ratio (Primary air:Secondary air:Tertiary air=91%:9%:0%, 82%:9%:9%, 73%:9%:18%). NO and CO concentrations in flue gas, profiles of temperature and pressure at the height of the combustion, unburned carbon in sampled fly ash and combustion efficiency on operating conditions were evaluated. As notable results, NO concentration with air-staging application under tertiary air supply at 9.4 m in the combustor reduced 100.7 ppm compared to 148.8 ppm without air-staging while, CO concentration increased from 52.2 ppm without air-staging to 99.8 ppm with air-staging. However, among air-staging runs, when tertiary air supply amount at 6.4 m in the combustor increased by air-staging ratio (Primary air:Secondary air:Tertiary air=73%:9%:18%), NO and CO concentrations decreased the lowest 90.8 ppm and 66.1 ppm, respectively. Furthermore, combustion efficiency at this condition was improved to 99.3%, higher than that (98.3%) of run without air-staging.