과열증기처리 반탄화 추출물의 항산화 효과 검증에 관한 연구

오근혜(Geun Hye Oh),남정빈(Jeong Bin Nam),양승민(Seung Min Yang),정원희(Won Hee Joung),정진산(Jin San Jeong),신종민(Jong Min Shin),강석구(Seog Goo Kang) 한국펄프·종이공학회 2018 펄프.종이기술 Vol.50 No.2

The antioxidant properties of the extracts from torrefied wood subjected to superheated steam treatment were investigated. Total polyphenolics, total flavonoids, DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity, reducing power, and FRAP (Ferric reducing antioxidant power) were determined to evaluate antioxidant activity. The total polyphenol content was 879.67±40.41 ㎎/mL at a concentration of 25 g/mL when the extract was subjected to a temperature of 300℃ for 10 min, and 759.67±25.17 ㎎/mL at a concentration of 25 g/mL at 350℃ for 10 min. The value of at 300℃ was 15.79% higher than that obtained at 350℃. Total flavonoid content was 111.18±3.55 ㎎/mL at a concentration of 25 g/mL at 300℃ for 10 min, and 80.58±2.58 ㎎/mL at a concentration of 25 g/mL at 350℃ for 10 min. The value at 300℃ was 37.97% higher than that obtained at 350℃. For the DPPH free radical scavenging activity, the highest scavenging activity was observed at a concentration of 6 g/mL. DPPH free radical scavenging activity at a concentration of 6 g/mL at 300℃ for 10 min was 89.83±0.03%, whereas at 350℃ for 10 min at the same concentration, it was found to be 87.99±0.1%. The value at 300℃ was 2.09% higher than that obtained at 350℃. Reducing power was determined to be 3.59±0.04 at a concentration of 25 g/mL at 300℃ for 10 min, and 2.92±0.1 at a concentration of 25 g/mL at 350℃ for 10 min. The value at 300℃ was 22.94% higher than that obtained at 350℃. FRAP was 1742±37 μM at a concentration of 25 g/mL at 300℃ for 10 min, and 1106±8 μM at a at 350℃ for 10 min. At 300℃, the FRAP value was 57.50% higher than that obtained at 350℃. Based on these results, we suggest that torrefied wood treated with superheated steam can be used in various applications because of its effective antioxidant properties.

저산소성 허혈성 뇌손상을 유발시킨 어린 백서에서 Myeloperoxidase 측정 검사

양혜정(Hae Joung Yang),피대훈(Dae Hun Pee),임지혜(Ji Hye Lim),최병민(Byung Min Choi),이기형(Kee Hyoung Lee),은백린(Baik-Lin Eun) 대한소아신경학회 2002 대한소아신경학회지 Vol.10 No.2

목 적 : 예전에는 뇌경색 부위에서 발견되는 백혈구를 단지 뇌손상에 뒤따르는 생리적인 반응으로만 생각하였으나 최근 10년 사이 재관류 손상에서도 백혈구에 의한 염증 작용이 중요한 역할을 한다고 알려지면서 이들의 역할에 대한 연구가 새롭게 이루어지고 있다. PML의 존재는 세포질내 과립에서 분비되는 MPO를 생화학적으로 측정함으로서 증명할 수 있는데 저자들은 미성숙 뇌에서 저산소성 허혈증에 의한 뇌손상이 발생할 때 백혈구가 침윤되는 과정을 MPO 측정 검사를 통하여 관찰하였고, P와 L-selectin 억제제인 Fucoidin을 투여한 후 MPO의 변화를 확인하였다. 방 법 : 생후 7일된 어린 흰쥐를 사용하여 우측총 경동맥을 전기 응고시켜 자르고 8% 산소에 노출시켰다. 저산소 노출 후 회복 시간에 따라 동물을 희생시키고 뇌를 추출하여 뇌조직 1 g당 10mL의 20 mM potassium Phosphate buffer(pH 7.4)를 첨가하여 50초간 분쇄하였다. 각각의 균질회된 조직 샘플들은 4℃에서 20분 동안 원심 분리하여 상층액을 제거한 후, 침전물은 처음 조직량에 따라 조직 1 g당 10 mL의 0.5% cetylditrimethylethyl ammonium bromide(wt/vol)가 첨가된 50 mM potassium phosphate buffer(pH 6.0)를 첨가하였다. Vortex를 이용하여 buffer와 침전물을 잘 섞고 60℃수조에서 120분 동안 방치하였다. 그 후 각 조직 샘플들을 4 watts에서 음파처리하고 4℃에서 15분 동안 원심 분리를 시행하여 상층액을 새로운 tube에 옮겼다. MPO 측정검사를 위한 MPO reaction buffer는 50 mM potassium phosphate buffer(pH 6.0) 100 mL에 0.53 mM odianisidine edihydrochlorde와 0.0005% HO를 섞어 만들었다. MPO reaction solution 2.9 mL에 각각의 MPO sample 0.1 mL을 첨가하여 460 nm의 파장에서 5분 동안 MPO에 다른 흡광도 차이를 관찰하였다. 결 과 : 조직내 백혈구 침윤의 지표로 측정한 MPO 활성도는 대조군에서는 미미하였으나 총 경동백을 절단한 우측 대뇌군에서는 허혈 및 저산소증 유발 후 8시간째부터 현저히 증가되기 시작하여 24시간 경과 후 발현이 가장 높았으며, Fucoidin 50 mg/kg으로 전처치한 약물 실험군에서는 MPO 활성도가 현저히 감소하였다. 결 론 : 백혈구는 미성숙 뇌의 저산소성 허혈증에 의한 뇌손상에서 중요한 매개체 역할을 하며, 백혈구의 생화학적 활성도를 나타내는 MPO 활성도는 저산소성 허혈성 뇌손상의 정도를 측정하는 지표로 이용될 수 있다고 생각된다. Purpose : Neutrophils found around an infarcted area in the brain was once considered as only the physiologic response following the brain injury, but recent studies have shown that inflammatory responses by neutrophils play an important role in the reperfusion injury. The presence of ploymorphonuclear leukocytes(PML) is proven by biochemical assay of myeloperoxidase(MPO) Secreted in the cytoplasmic granules. We observed the process of PML infiltration on hypoxic-ischemic brain injury of immature rats by the assay of MPO activity and changes of the MPO activity after the administration of fucoidin, inhibitor of P- and L-selectin. Methods : We used a well characterized model of the brains of 7 day-old-rats, which had unilateral hypoxic and ischemic injuries(HI). Those injuries were induced by unilateral carotid artery ligation followed by timed exposure to hypoxic inspiratory gas mixture(8% O). MPO activity was measured in the brain tissue homogenates of HI rats(n=18) at 0, 2, 8, 24 and 48 hrs and in rats that received fucoidin immediately before and again after hypoxia(50 mg/kg, n=6) at 8 and 24 hrs. Controls(n=2) were rats with neither hypoxia nor ischemia. The brain samples were homogenized in 20 mM potassium phosphate buffer(pH 7.4) for 50 secs. The homogenate was centrifuged at 14,000 g at 4℃ for 15 mins and the supernatant was discarded. The tissue was pulverized, weighed, and suspended in 1 mL of 50 mM potassium phosphate buffer solution(pH 6.0) contatining 0.5% cetylditrimethylammonium bromide(wt/vol). The tissue was sonicated and centrifuged at 10,000 g for 15 mins. 200 µL of the supernatant was mixed with 1 mL of 50 mM potassium phosphate buffer solution(pH 6.0) containing 10 μL of 1.325 mM o-dianisidine hydrochloride and 170 µL of 3% hydrogen peroxide(vol/vol). Changes in absorbance at 460 nm were measured for 5 mins by using microplate reader. One unit of MPO activity was defined as that degrading 1 µmol peroxide/min at 25℃, and the result was expressed as units of MPO/100 gm tissue. Results : In HI rats, MPO activity increased at 2 hrs after HI and peaked at 24 hrs in the right hemisphere. In rats with fucoidin treatment immediately before and again after hypoxia, the MPO activity significantly decreased in both hemispheres compared with HI rats(P<0.05). MPO activity in the tissue of control rats was insignificant. Conclusion : The dynamic changes of the MPO activity suggest the important role of PMN on hypoxic-ischemic brain injuries in immature rats. MPO activity could be used as an index of the severity of injuries of hypoxic-ischemic brains.

A Quantitative A naly sis of the Fire Hazard Generated from Hydrogen Fuel Cell Electric Vehicles

Sungwook Kang(Sungwook Kang),Kyu Min Lee(Kyu Min Lee),Minjae Kwon(Minjae Kwon),Ohk Kun Lim(Ohk Kun Lim),Joung Yoon Choi(Joung Yoon Choi) 한국화재소방학회 2022 International Journal of Fire Science and Engineer Vol.36 No.2

There is a lack of information on (i) the potential fire load of new green-technology vehicles, (ii) flame spread behavior, (iii) thermal impacts on high-pressure hydrogen storage vessels (HSVs) and lithium-ion batteries (LIBs) during fuel cell electric vehicles fires (FCEVs), and (iv) thermal damage to adjacent vehicles and upper structural members during FCEV fires occurring in civil structures, such as underground spaces, multi-story parks, and tunnels. In view of this, a full-scale fire test was conducted in this study to quantitatively assess the fire risk of hydrogen FCEVs. Large-scale cone calorimetry was used to quantify the thermal intensity released from the FCEV fire. The flame spreading behavior through an FCEV with HSVs and LIBs was observed using the thermocouples installed. Changes in the temperature and irradiance around the FCEV fire were also measured using an instrumented test rig. The peak heat release rate, total heat released, and fire growth rate were observed to be 5.99 MW, 11.8 GJ, and 0.0055 kW/s², respectively. The temporal point of hydrogen gas release from the HSVs' thermal pressure relief device (TPRD) was estimated to be 16.2-26.2 min. The initiation of thermal runaway of LIBs was deduced from the temperature-time profiles of the LIB modules and their metal housing approximately 22.2 min after HCEV ignition. Moreover, FCEV fires could thermally impair adjacent upper structural members by 800 ℃ combustion gas for at least 13 min and emit a median heat flux of 27.2 kW/m² (peak heat flux of 76.5 kW/m²) to adjacent vehicles. The measurements and findings obtained from this study can contribute to the evaluation of and further studies on newly emerging fire hazards.

오염수계 내 세슘 제거를 위한 대나무 활성탄의 흡착효율 규명

안정필(Joung pil Ahn),이민희(Min hee Lee) 대한자원환경지질학회 2018 자원환경지질 Vol.51 No.2

세슘은 물속에서 고상보다는 이온이나 착염 등 용존 형태로 존재하는 특성이 강하여, 오염 수계로부터 세슘 제거가 어려운 것으로 알려져 있다. 최근 많은 연구들이 수계 내에서 세슘의 제거효율이 높은 흡착제를 개발하는데 집중하고 있다. 본 연구에서는 대나무 활성탄을 흡착제로 사용하여 수계 내에 존재하는 세슘을 효과적으로 제거하는 실내실험을 실시하였다. 수용액으로부터 대나무 활성탄의 세슘 제거효율을 측정하고, 최적의 세슘 제거능을 가지는 흡착 조건을 도출하고자 다양한 조건에서 흡착 배치실험을 수행하였다. 국내에서 유통되고 있는 5 종류의 대나무 활성탄의 표면 특성을 SEM-EDS와 XRD 분석으로 규명하였으며, 이 중에서 비표면적이 큰 3 종류의 대나무 활성탄을 대상으로 세슘 제거 배치실험을 실시하였다. 다양한 초기 세슘 농도를 가지는 인공수(0.01 ~ 10 mg/L 범위)를 대상으로 대나무 활성탄에 의한 수용액 내 세슘 제거량을 측정하여 제거효율을 계산하였고, 두 종류의 흡착 등온식들을 흡착 배치실험결과에 대응시켜 흡착 상수값을 결정함으로서, 대나무 활성탄의 세슘 흡착 특성을 규명하였다. FE-SEM 분석 결과, 대나무 활성탄은 표면이 다수의 기공을 포함하는 대나무의 섬유질 조직을 그대로 유지하는 입자들로 구성되어, 이들 섬유질 조직 내 다양한 형태의 기공들과 엽상조직 표면들이 주요 세슘 흡착공간인 것으로 밝혀졌다. 흡착 배치실험결과, C type 대나무 활성탄의 세슘 제거효율이 가장 높았는데, 특히 수용액의 세슘 초기 농도가 1.0 mg/L 이하인 경우에도 75 % 이상(최고 82 %)을 나타내어, 원전사고 등에 의해 오염된 현장 지하수나 지표수(해수 포함)의 세슘농도가 대부분 1.0 mg/L 이하임을 고려하면, 실제 오염수 정화 가능성이 높을 것으로 밝혀졌다. 수용액의 온도는 5-15℃ 범위, pH는 3-11 범위에서 높은 세슘 제거효율이 일정하게 유지되는 것으로 나타나 다양한 오염수에 적용할 수 있을 것으로 판단되었다. 흡착 배치실험 결과는 Langmuir 흡착모델과 유사하였으며, C type 대나무 활성탄의 최대흡착농도(qₘ: mg/g)값은 63.4 mg/g으로 기존의 상용화된 흡착제 값보다 높았고, 수용액의 초기 세슘 농도가 1.0 mg/L이하인 경우 표면흡착률(surface coverage) 값도 낮게 유지되어, 적은 양의 세슘으로 오염된 수계를 효과적으로 정화할 수 있음을 입증하였다. The cesium (Cs) removal from the contaminated water system has been considered to be difficult because the cesium likes to exist as soluble phases such as ion and complexes than the solid in water system. Many researches have focused on developing the breakthrough adsorbent to increase the cesium removal efficiency in water. In this study, the laboratory scale experiments were performed to investigate the feasibility of the adsorption process using the bamboo charcoal for the Cs contaminated water system. The Cs removal efficiency of the bamboo charcoal were measured and the optimal adsorption conditions were determined by the adsorption batch experiments. Total 5 types of commercialized bamboo charcoals in Korea were used to identify their surface properties from SEM-EDS and XRD analyses and 3 types of bamboo charcoals having large specific surface areas were used for the adsorption batch experiment. The batch experiments to calculate the Cs removal efficiency were performed at conditions of various Cs concentration (0.01 - 10 mg/L), pH (3 - 11), temperature (5 - 30℃), and adsorption time (10 - 120 min.). Experimental results were fitted to the Langmuir adsorption isotherm curve and their adsorption constants were determined to understand the adsorption properties of bamboo charcoal for Cs contaminated water system. From results of SEM-EDS analyses, the surfaces of bamboo charcoal particles were composed of typical fiber structures having various pores and dense lamella structures in supporting major adsorption spaces for Cs. From results of adsorption batch experiments, the Cs-133 removal efficiency of C type bamboo charcoal was the highest among those of 3 bamboo charcoal types and it was higher than 75 % (maximum of 82 %) even when the initial Cs concentration in water was lower than 1.0 mg/L, suggesting that the adsorption process using the bamboo charcoal has a great potential to remove Cs from the genuine Cs contaminated water, of which Cs concentration is low (< 1.0 mg/L) in general. The high Cs removal efficiency of bamboo charcoal was maintained in a relatively wide range of temperatures and pHs, supporting that the usage of the bamboo charcoal is feasible for various types of water. Experimental results were similar to the Langmuir adsorption model and the maximum amount of Cs adsorption (qm : mg/g) was 63.4 mg/g, which was higher than those of commercialized adsorbents used in previous studies. The surface coverage (θ) of bamboo charcoal was also maintained in low when the Cs concentration in water was < 1.0 mg/L, investigating that the Cs contaminated water can be remediated up with a small amount of bamboo charcoal.

이차함수에서 두 변량사이의 관계 인식 및 표현의 발달 과정 분석: 민선의 경우를 중심으로

이동근 ( Dong Gun Lee ),문민정 ( Min Joung Moon ),신재홍 ( Jaehong Shin ) 한국수학교육학회 2015 수학교육 Vol.54 No.4

The aim of this qualitative case study is twofold: 1) to analyze how an eleventh-grader, Min-Seon, conceive and represent a pattern of change between two varying quantities in a quadratic functional situation, and 2) further to help her form a concept of ``derivative`` as a tool to express the relationship with employing a concept of ``rate of change.`` The result indicates that Min-Seon was able to construct graphs of piecewise functions that take average rates of change as range of the functions, and managed to conjecture the derivative of a quadratic function, y=x ^{2}. In conclusion, we argue that covariational approach could not only facilitate students`` construction of an initial function concept, but also support their understanding of the concept of ``derivative.``

The Effect of Attenuation and Scatter Correction in Rat Brain PET

Yu, A. R.,Jin Su Kim,Jisook Moon,Hee Joung Kim,Sang Moo Lim,Kyeong Min Kim IEEE 2013 IEEE transactions on nuclear science Vol.60 No.2

<P>Attenuation correction (AC) and scatter correction (SC) are problematic issues for animal positron emission tomography (PET). In this study, the effects of AC and SC were assessed using PET on a phantom and actual rat brain. Transmission (TX) was performed using <SUP>57</SUP>Co for 15 min. After a 15 min TX scan, emission (EM) PET was performed in list mode for 1 h. To assess the effects of AC and SC, the spillover ratio (SOR) was measured using a rat-sized NEMA NU4 image-quality phantom; statistical parametric mapping (SPM) was performed to assess the effects of AC and SC in the rat brain using 18<SUP>F</SUP>-FDG (FDG). In addition, the binding potential (BP) was compared for <SUP>18</SUP>F-FP-CIT (FP-CIT) PET. SPM was used to compare PET images to which AC and SC were applied, and BP was used for FP-CIT PET. The SORs of air and water decreased after AC and SC. SPM for FDG PET after AC showed a significant increase in FDG-measured activity in the cerebellum and occipital cortex. After AC/SC, a significant decrease in FDG-measured activity was observed in the frontal and temporal cortices. For FP-CIT PET of the rat brain, the BP decreased by 26% after AC because the FP-CIT uptake increased more in the cerebellum than in the striatum owing to AC. After AC and SC, the mean BP increased by 61%. AC and AC/SC were found to be necessary components of the artifact correction process for both FDG PET and FP-CIT PET of rat brains.</P>

도심 수목원에서의 경관감상과 산책이 인체의 생리적 안정에 미치는 영향

박범진 ( Bum Jin Park ),가재남 ( Jae Nam Ka ),이민선 ( Min Sun Lee ),김선아 ( Seon A Kim ),박민우 ( Min Woo Park ),최윤호 ( Yoon Ho Choi ),정다워 ( Da Wou Joung ),권치원 ( Chi Weon Kwon ),염동걸 ( Dong Geol Yeom ),박순주 ( Soon Jo 한국산림과학회 2014 한국산림과학회지 Vol.103 No.4

This research was conducted to investigate the impact of viewing scenery and walking in the urban forest onphysiological relaxation of humans. The experiment was conducted in Hanbat Arboretum located in Daejeon, and thecontrol experiment was conducted in front of Daejeon City Hall. The subjects that participated in the experimentcomprised 24 Korean male university students in their 20s (average age, 21.1±2.5 years), participated in the experimentas the subject, and these subjects were classified into three groups divided into three locations such as the pine forest inArboretum, the pond in Arboretum, and the city. The subjects sat down and viewed scenery for 10 min, and they thenwalked for 15 min. Further, physiological changes were measured using indicators such as heart rate variability (HRV),blood pressure, and pulse rate. As a result, when subjects viewed scenery and walked in the urban forest, a statisticallysignificant increase in the high frequency (HF) power of HRV and decrease in systolic pressure was observed comparedwith when subjects viewed scenery and walked in the city. Through this research, it was found that activities like viewingscenery or walking in Arboretum of the city are effective in increasing the physiological relaxation of the city residents.

X-band 주파수대역에서 동작하는 다이오드 주파수 혼합기 설계 및 제작

정민규,서영석,안창회 영남대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.28 No.2

In this paper reports on the design and performance of microstrip single balanced diode mixer, using GaAs Schottky diode, at X-band. A single balanced diode mixer is designed and implemented using Harmonic balance simulation(MW-office). The diode model parameters are extracted by SPICE model of diode. The diode impedances for the LO, RF, and IF frequencies and Powers are calculated for diode matching network design. The mixer consists of branch line coupler, Low pass filter and RF&LO choke for bias circuit. The Passive circuits are simulated for accuracy by EM-simulation of MW-office. The Mixer requires 10dBm local oscillator(LO) power without dc bias and achieves a conversion loss of about 7.5dB, 17dB LO-to-RF isolation, 40dB LO-to-IF isolation, 30dB RF-to-IF isolation, and 1.16 LO VSWR.

바나듐이 도핑된 강유전체 Bi₄Ti₃O_12 박막(BTV)의 성장과 특성

정원태,최은경,김현주,강민진,김상수 昌原大學校 基礎科學硏究所 2001 基礎科學硏究所論文集 Vol.13 No.-

Bi3.99Ti2.97V0.03O12 (BTV) thin films with 3 mol% vanadium doping were prepared on Pt/Ti/SiO2/Si substrate by sol-gel method. X-ray diffraction analysis indicated that single-phase lapered perovskite were obtained and preferred orientation was not observed. Under the annealing temperature at 600℃, the surface morphology of the BTV thin films had fine-rounded particles and then changed plate-like at 650℃ and 700℃. The remanent polarization (2Pr) and coercive field (2Ec) of 700℃ annealed BTV thin film were 25 μC/cm2 and 116 kV/cm, respectively. In addition, BTV thin film showed little polarization fatigue during 109 switching cycles. These improved ferroelectric properties were attributed to the increased rattling space and reduced oxygen vacancies by substitution Ti4+ ion (68 pm) with smaller V5+ ion (59 pm). The dielectric constant and loss were measured 130 and 0.03 at 10 kHz, respectively.

공침법에 의한 Y₁-_(x)Ca_(x)Ba₂Cu₃O_(7-8)분말의 제조

정민교,박병춘,이완재 한양대학교 이학기술연구소 2002 이학기술연구지 Vol.5 No.-

Y₁_(x)Ca_(x)Ba₂Cu₃O_(7-8) powder was synthesized by a coprecipitation method. This process is very easy to control the chemistry of the cation's solutions and coprecipitation with oxalic acid. Starting materials Of nitrates such Y(NO₃)₂ · 6H₂0, Ca(NO₃)₂ · 4H₂0, Ba(NO₃)₂and Cu(NO₃)₂ · xH₂O were dissolved into distilled water. Each solution was mixed and pH-controlled with oxalic acid The best condition of coprecipitation was pH 1.3 at room temperature. The yield of precursor was up to 92%. After calcining at 850℃ in air, 123 single phase was obtained. The size of 123 phase powder was about 90nm.