• Journal of Korea Foresty Energy
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• v.24 no.1
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• pp.39-46
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• 2005

In this study, the possibility of sugar conversion of poplar wood(Populus $alba{\times}rglandulosa$) and their degradation features of major wood components were characterized using flow type supercritical water treatment system. The finely ground poplar wood meals were treated for 2min. under subcritical condition$(23MPa,\;275^{\circ}C\;and\;325^{\circ}C)$ and supercritical condition $(23MPa,\;375^{\circ}C\;and\;415^{\circ}C)$. respectively. The degradation products of poplar wood meals appeared brownish colors, including undegraded solids. Increasing the temperature of the system, the degradation rate of poplar wood meals was accelerated and reached up to $94\%\;at\;375^{\circ}C$. The total amount of reducing sugars in degradation products determined by DNS method were gradually lowered when the temperature condition became severe. This indicated that the reducing sugars formed were further degraded to kan derivatives by certain side reaction such as pyrolysis under higher temperature. In order to characterize degradation features of lignin, the degradation products were extracted with ethylacetate and the organic phases were subjected to GC-MS analysis. Main lignin degradation products were identified to vanillin, guaiacol, syrinaldehyde, 4-prophenyl syringol and dihydrosinapyl alcohol, which could be formed by the cleavage of ether linkages in lignin polymers by high temperature condition.

• Korean Journal of Poultry Science
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• v.13 no.2
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• pp.221-226
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• 1986

In order to study the effect of feeding moldy corn in the feed and to compare the efficacy of several antidotical treatments, a feeding trial was conducted using broiler chickens. Ground yet low corn was adjusted to contain 20% moisture and then incubated at 35$^{\circ}C$ for 20 days. The number of fungi increased from 11${\times}$10$^4$/g to 42 10$\^$7/g on incubation but aflatoxins (B$_1$, B$_2$, G$_1$, G$_2$) were not detected by TLC test. Moldy corn was included in the experimental diets at the level of 7% with various treatments. Thirty six hatched male broiler chickens were divided into 6 groups and each group was placed for 4 weeks on one of the following treatments: Fresh corn, Moldy corn, Ammoniated (1.5%) moldy corn, Moldy corn＋BHT (0.1%), Moldy corn CTC (100ppm) and Moldy corn＋Probiotics. Weight gains of the birds fed Ammoniated moldy corn diet, Moldy corn＋Probiotics dist and Moldy corn＋CTC diet were greater by 6.1%. 7.6% and 3.9% respectively than those fed Moldy corn diet. The feed efficiencies of Moldy corn＋Probiotics diet and Moldy corn＋CTC diet were better than those of Moldy corn diet. Dry matter contents of the livers of the birds fed Ammoniated moldy corn diet, Moldy corn＋BHT diet and Moldy corn diet were lower than those of other treatments. Proteion contents of the livers of the birds fed Moldy corn diet, Moldy corn ＋CTC diet and Moldy corn＋BHT diet were lower than those of other treatments. Moldy corn tended to increase fat content of the livers.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.285-291
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• 1996

The effect of various packaging methods on Kimchi quality was investigated in order to develop the packaging techniques for preventing commercial Kimchi Products from ination and explosion due to fermentative gas evolved during storage and distribution. Kimchi was packaged in different methods; atmospheric (AP), check-valved (CV), double (DP) and vacuum (VP) packaging. The quality of Kimchi during storage at $10^{\circ}C$ was evaluated ill terms of gas composition, free volume, pH, titratable acidity, color index, lactic acid bacteria and sensory properties. $O_2$ concentration decreased to about 1% at $6{\sim}8$ days of optimal ripening time in all packages except DP, in which it remained around 20%. $CO_2$ concentration reached $70{\sim}90%$ after $6{\sim}8$ days in AP, CV and DP, while it stayed around 10% in DP. The free volume in AP had typical sigmoidal curve similar to $CO_2$ concentration changes. It remained almost constant in CV and DP, but started to increase at the late stage of storage In VP. There was no significant influence of packaging methods on the other quality attributes such as pH, titratable acidity, color index (L.b/a), lactic acid bacteria count and sensory evaluation score. As results, it could be proposed to employ CV and DP method as the effective packaging techniques for preventing commercial Kimchi products from inflation.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.21-21
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• 2018

본 연구는 북방계 식물에 속하는 두메우드풀[Woodsia ilvensis (L.) R.Br.]의 전엽체 증식 및 포자체 형성을 위한 적정방법을 구명하고자 수행되었다. 식물재료는 경상북도 의성군 일대에서 채취한 후 청주의 일반하우스에 이식하여 재배하였다. 포자 성숙기인 8월에 채종하여 발아시켰으며, 포자로부터 획득한 전엽체를 8주간 계대하면서 실험재료로 사용하였다. 전엽체 300mg을 메스로 다진 후 배지농도 및 종류(Knop, 1/4, 1/2, 1 및 2MS)를 달리하여 8주간 배양하였다. 배양실의 온도는 $25{\pm}1.0^{\circ}C$, 광도는 $30{\pm}1.0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$(16/8h)로 조절되었다. 연구의 결과, 배지구성물질의 농도가 높았던 2MS배지에서 전엽체의 생체중이 12.4g으로 41배 증가하여 가장 높은 증식율을 나타냈다. 또한 배지구성물질의 농도가 적을수록 생체중의 증가폭도 함께 감소하는 경향을 보였다. 포자체 형성에 적합한 토양조건을 확인하고자, 원예상토, 피트모스, 펄라이트 및 마사토의 비율을 달리한 5종류의 혼합토양을 조성하여 사각분($7.5{\times}7.5{\times}7.5cm$)에 충진하였다. 다음으로 전엽체 1g을 핸드블랜더로 10초간 분쇄 후 충진된 사각분 위에 고르게 분주하여 14주간 재배하였다. 재배환경은 온도 $25{\pm}1.0^{\circ}C$, 광도 $43{\pm}2.0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$(16/8h) 및 습도 $72{\pm}2.0%$로 조절되었다. 지베렐린 수용액이 포자체 형성에 미치는 영향을 조사하고자, 선행연구에서 선발된 토양조건을 기준으로 침지농도(0, 50, 100, $200mg{\cdot}L^{-1}$)를 조절하여 1시간 침지 후 상기와 동일한 방법으로 재배하였다. 연구의 결과, 원예상토와 펄라이트 또는 마사토를 2:1(v:v)로 혼용한 토양에서 사각분 당 109.5, 128.8개의 포자체가 형성되었다. 한편, 피트모스가 첨가된 처리는 포자체의 형성이 억제되는 경향을 나타냈다. 지베렐린 50과 $100mg{\cdot}L^{-1}$ 수용액에 침지한 처리에서 무처리에 비해 많은 사각분 당 각 177.0, 181.7개의 포자체가 형성되었으며, 생육도 양호하였다.

• Resources Recycling
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• v.16 no.5
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• pp.71-76
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• 2007

The mixed plastic waste generated from households after hand-picking and/or mechanical sorting processes amounts to 1,750,000 ton in 2006, and most of these waste are finally end up with landfill and/or incineration due to the lacks of separation technologies and economical reasons. The mixed plastic wastes can not be used as raw materials for chemical and/or thermal recycling processes because of their high content of PVC(upto 4.0 wt.%). In the present research, gravity separation system has been developed to remove PVC from the mixed plastic waste and to recover the PO-type plastics. This system mainly consists of air classification, magnetic separation, one-step crushing, feeding system at fixed rate and wet-type gravity separation system. The gravity system based on centrifugal separation has been developed at capacity of 0.5 ton/h and it consists of mixing, precleaning, separation, dewatering, recovery system and wastewater treatment system, etc. The main objective of this process is to achieve high separation efficiency of polyolefins with less than 0.3 wt.% PVC content and less than 10% moisture content in the final products. In addition, a crushing unit of with 8 rotor system is also developed to improve the crushing efficiency of soft-type plastics. The system with a capacity of 1.0 ton/h is developed and operational results are presented.

• Food Science and Preservation
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• v.24 no.8
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• pp.1088-1093
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• 2017

This study was conducted to investigate the effects of drying methods for Citrus junos peels on quality characteristics of the hot-water leachate from teabags containing those peels. Fresh peels were hot-air ($50^{\circ}C$), cold-air ($30^{\circ}C$), or freeze-dried ($-45^{\circ}C$), powdered to a size of 40 mesh, packaged with a paper sachet, and then the packaged teabags were leached for 10 min with hot-water ($70^{\circ}C$). $L^*$ value (lightness) and $-a^*$ value (greenness) of the peel powder were the highest in the freeze-dried samples. Soluble solids and titratable acidity of the teabag leachate were in the following order; cold-air, freeze, and hot-air dried samples. Among free sugar contents in all samples, fructose content was the highest, followed by glucose and sucrose. Fructose and glucose contents were not affected by drying methods. There was no significant difference in the flavonoid content among the peels dried using three drying methods. DPPH radical-scavenging activity of the leachate was the highest in the cold-air dried sample. These results suggest that cold-air drying would be an effective method to enhance the quality of hot-water leachate of teabags prepared from C. junos peels.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.346-346
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• 2007

압전세라믹 재료는 현재 압전 변압기, actuator, transducer, sensor, speaker 등에 광범위하게 이용이 되고 있다. 이 중에서 압전세라믹 소결체를 이용한 스피커의 제조는 가공이 까다롭고, 대형의 크기로 제작 시 소자가 깨지는 등의 많은 제약을 받고 있으며, 저음 특성이 떨어져 응용 범위가 한정되어 있다. 따라서 최근에는 이러한 단점을 극복하기 위하여 세라믹/고분자 복합체를 이용한 필름 스피커를 제작하고자 시도하고 있다. 이러한 세라믹/고분자 0-3형 압전 복합체를 이용할 경우, 제품의 경량화를 실현할 수 있고, 크기나 환경의 영향을 거의 받지 않으므로, 고기능성 스피커로의 응용에 적합할 것으로 보인다. 따라서 본 연구에서는 PZT계의 세라믹와 PVDF, PVDF-TrFE, Polyester, acrylic resin 등의 여러 고분자 물질과의 복합체를 제조하여 압전특성을 평가하였다. 본 실험은 먼저 $(Pb_{1-a-b}Ba_aCd_b)(Zr_xTi_{1-x})_{1-c-d}(Ni_{1/3}Nb_{2/3})_c(Zn_{1/3}Nb_{2/3})_dO_3$ (이하 PZT라 표기)의 최적화 조성을 선택하여, $1050^{\circ}C$에서 소결된 분말을 48시간 ball milling방법 로 약 $1{\mu}m$ 크기로 분쇄하였다. 고분자 물질들은 알맞은 용제들을 선택하여 녹였다. 그 다음 소결된 PZT분말과 고분자를 50:50, 60:40, 65:35, 70:30등의 무게 분율로 혼합하고, 분산제, 소포제 등을 첨가하여 3단 roll mill을 이용하여 충분히 분산시켜 페이스트 (Paste)를 제조하였다. 제조된 페이스트를 ITO가 코팅된 PET필름 위에 스크린 프린팅 법을 사용하여 인쇄하여 $120^{\circ}C$에서 5분간 건조하였다. 코팅된 복합체의 두께는 약 $80{\mu}m$ 정도로 측정되었다. Ag 페이스트를 이용한 상부 전극 형성에도 스크린 프린팅 법을 적용하였다. 이를 $120^{\circ}C$에서 4 kV/mm의 DC 전계로 분극 공정을 수행한 후 전기적 특성을 평가하였다. 유전특성을 조사하기 위해서 LCR meter (EDC-1620)를 사용하였고, 시편의 결정구조는 XRD (Rigaku; D/MAX-2500H)을 통해 분석하였으며, 전자현미경(SEM)을 이용하여 미세구조를 분석하였다. 압전 전하상수$(d_{33})$ 값은 APC 8000 모델을 이용하여 측정하였다. PZT의 혼합비가 증가할수록 비유전율 및 압전 전하 상수 등의 전기적 특성이 증가되었다. 또 여러 고분자 물질 중에서 PVDF-TrFE 수지가 가장 우수한 특성을 보였다. 이는 PVDF-TrFE 수지가 압전성을 나타내기 때문인 것으로 판단되었다.

• Journal of Soil and Groundwater Environment
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• v.14 no.5
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• pp.62-70
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• 2009

A field soil highly contaminated with petroleum hydrocarbons (JP-8 and diesel fuels) was employed for its remediation by a lab-scale thermal desorption process. The soil was collected in the vicinity of an underground storage tank in a closed military base and its contamination level was as high as 4,476 ppm as total petroleum hydrocarbon (TPH). A lab scale directly-heated low temperature thermal desorption (LTTD) system of 10-L capacity was developed and operated for the thermal treatment of TPH contaminated soils in this study. The desired operation temperature was found to be approximately $200-300^{\circ}C$ from the thermal gravimetric analysis of the contaminated field soils. The removal efficiencies higher than 90% were achieved by the LTTD treatment at $200^{\circ}C$ for 10 min as well as at $300^{\circ}C$ for 5 min. As the water content in the soils increased and therefore they were likely to be present as lumps, the removal efficiency noticeably decreased, indicating that a pre-treatment such as field drying should be required. The analysis of physical and chemical properties of soils before and after the LTTD treatment demonstrated that no significant changes occurred during the thermal treatment, supporting no needs for additional post-treatments for the soils treated by LTTD. The results presented in this study are expected to provide useful information for the field application and verification of LTTD for the highly contaminated geo-environment.

• Resources Recycling
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• v.29 no.4
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• pp.3-14
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• 2020

Titanium sponge is industrially produced by the Kroll process. In order to understand the importance of the emerging smelting and recycling process, it is necessary to review the conventional production process of titanium. Therefore this paper provides a general overview of the conventional titanium manufacturing system mainly by the Kroll process. The Kroll process can be divided into four sub-processes as follows: (1) Chlorination of raw TiO₂ with coke, by the fluidized bed chlorination or molten salt chlorination (2) Magnesium reduction of TiCl₄ and vacuum distillation of MgCl₂ and Mg by reverse U-type or I-type with reduction-distillation integrated retorts (3) Electrolysis process of MgCl₂ by monopolar cells or multipolar cells to electrolyze into chlorine gas and Mg. (4) Crushing and melting process in which sponge titanium is crushed and then melted in a vacuum arc furnace or an electron beam furnace Although the apparatus and procedures have improved over the past 80 years, the Kroll process is the costly and time-consuming batch operation for the reduction of TiCl₄ and the separation of MgCl₂.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.57-57
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• 2019

본 연구는 관상 및 조경용으로 개발이 가능한 남방계 양치식물인 점고사리[Hypolepis punctata (Thunb.) Mett.]의 전엽체 증식 및 포자체 형성에 적합한 배양조건을 구명하고자 수행되었다. 무가온 온실에서 성숙한 포자엽을 채집한 후 포자를 기내에서 발아시켜 전엽체를 획득하였으며, 8주 간격으로 계대배양 하여 실험의 재료로 사용하였다. 배지종류에 따른 전엽체의 증식 및 형태형성을 확인하고자, 배양된 전엽체 0.3g을 메스로 잘게 다진 후, 농도를 1/4, 1/2, 1, 2배로 조절한 MS배지에 8주간 배양하였다. 이후 선발된 배지를 기준으로 sucrose, 활성탄, 질소급원의 농도를 조절하여 전엽체의 증식과 형태형성을 확인하였다. 그 결과, 1MS배지에서 전엽체의 생체중이 초기 접종량인 0.3g에 비해 10.7배 증가한 3.2g으로 가장 높은 증가율을 보였다. 형태관찰에서도 장정기의 형성이 관찰되었으며, 전엽체의 쿠션조직이 비교적 잘 발달하였다. 전엽체 증식에 가장 좋은 효과를 보인 1MS배지를 기준으로 sucrose의 농도를 0-4%로 달리하여 실험한 결과, 1%의 처리구에서 6.7g으로 가장 높은 생체중을 보였다. 활성탄의 농도를 0-0.8%로 첨가한 네 처리구 중에서는 0.8%의 처리구에서 14.2g으로 무처리구에 비해 생체중이 2배 이상 증가하였다. 전엽체의 형태 또한 정상적인 발달을 보였다. 질소급원의 비율을 30-120mM로 조절한 배지에서는 60mM의 처리구에서 4.9g으로 가장 높은 생체중을보였다. 이후 포자체 형성을 위한 최적의 토양조건을 구명하고자, 원예상토, 피트모스, 펄라이트 및 마사토의 비율을 달리하여 5종류의 배양토를 조성하였다. 혼합된 토양은 사각분($7.5{\times}7.5{\times}7.5cm$)에 충진 하였으며, 배양된 전엽체 1g을 증류수와 함께 10초간 분쇄한 다음 준비된 토양표면에 분주하여 재배하였다. 12주간의 재배 결과, 원예상토를 단용한 토양에서 포자체의 수가 포트당 250.0개로 가장 많이 형성되었으며, 포자체의 생육 또한 다른 처리구에 비해 우수한 결과를 보였다. 한편 피트모스가 혼합된 토양에서는 포자체가 형성되지 않았다. 따라서 점고사리의 전엽체 대량증식에 적합한 배지는 sucrose 1%와 질소급원의 농도를 60mM, 활성탄을 0.8% 첨가한 1MS배지로 판단되며, 포자체 대량생산을 위해서는 원예상토를 단용한 토양이 적합하다고 판단된다.