• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.542-547
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• 2017

Ultrasound-assisted extraction (UAE) has attracted growing interest, as it is an effective method for the rapid extraction of bioactive compounds from plants with a high extraction efficiency comparable to the conventional extraction. In this study, UAE was used for the extraction of polyphenols from lipid extracted microalgae (Tetraselmis KCTC 12236BP) and the effects of five extraction variables on the total phenolic compounds (TPC) were studied. For the optimization of extraction parameters, particle size, solid-to-liquid (L/S) ratio, ethanol concentration, extraction temperature and extraction time have been examined as independent variables. All variables exhibited the significant effects on the extraction of TPC and extraction temperature showed the most significant effect among five variables. The optimal extraction conditions were the extraction using mixed particle, S/L ratio of 10%, ethanol concentration of 60%, extraction temperature of $100^{\circ}C$ and extraction time of 30 min, which gave the 8.7 mg GAE/g DW for TPC. Compared with conventional hot-water extraction, TPC extraction under UAE was increased by up to 1.8 fold with same extraction condition. This study showed that UAE under low temperature and short extraction time was proven to be an effective extraction process for TPC production from LEA compared to conventional hot-water extraction process.

• Preventive Nutrition and Food Science
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• v.21 no.2
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• pp.132-137
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• 2016

Enhanced production of individual phenolic compounds by subcritical water hydrolysis (SWH) of pumpkin leaves was investigated at various temperatures ranging from 100 to $220^{\circ}C$ at 20 min and at various reaction times ranging from 10 to 50 min at $160^{\circ}C$. Caffeic acid, p-coumaric acid, ferulic acid, and gentisic acid were the major phenolic compounds in the hydrolysate of pumpkin leaves. All phenolic compounds except gentisic acid showed the highest yield at $160^{\circ}C$, but gentisic acid showed the highest yield at $180^{\circ}C$. The cumulative amount of individual phenolic compounds gradually increased by 48.1, 52.2, and $78.4{\mu}g/g$ dry matter at $100^{\circ}C$, $120^{\circ}C$, and $140^{\circ}C$, respectively, and then greatly increased by $1,477.1{\mu}g/g$ dry matter at $160^{\circ}C$. The yields of caffeic acid and ferulic acid showed peaks at 20 min, while those of cinnamic acid, p-coumaric acid, p-hydroxybenzoic acid, and procatechuic acid showed peaks at 30 min. Antioxidant activities such as 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power values gradually increased with hydrolysis temperature and ranged from 6.77 to 12.42 mg ascorbic acid equivalents/g dry matter and from 4.25 to 8.92 mmol $Fe^{2+}$/100 g dry matter, respectively. Color $L^*$ and $b^*$ values gradually decreased as hydrolysis temperature increased from $100^{\circ}C$ to $140^{\circ}C$. At high temperatures ($160^{\circ}C$ to $220^{\circ}C$), L* and b* values decreased suddenly. The $a^*$ value peaked at $160^{\circ}C$ and then decreased as temperature increased from $160^{\circ}C$ to $220^{\circ}C$. These results suggest that SWH of pumpkin leaves was strongly influenced by hydrolysis temperature and may enhanced the production of phenolic compounds and antioxidant activities.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.441-449
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• 1994

The two reflective channels(red and near infrared spectrum) of advanced very high resolution radiometer(AVHRR) data were used to classify primary vegetation cover types in the Korean Peninsula. From the NOAA-11 satellite data archive of 1991, 27 daytime scenes of relatively minimum cloud coverage were obtained. After the initial radiometric calibration, normalized difference vegetation index(NDVI) was calculated for each of the 27 data sets. Four or five daily NDVI data were then overlaid for each of the six months starting from February to November and the maximum value of NDVI was retained for every pixel location to make a monthly composite. The six bands of monthly NDVI composite were nearly cloud free and used for the computer classification of vegetation cover. Based on the temporal signatures of different vegetation cover types, which were generated by an unsupervised block clustering algorithm, every pixel was classified into one of the six cover type categories. The classification result was evaluated by both qualitative interpretation and quantitative comparison with existing forest statistics. Considering frequent data acquisition, low data cost and volume, and large area coverage, it is believed that AVHRR data are effective for vegetation cover type mapping at regional scale.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.221-228
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• 1994

Respitation and growth rates of leaves, branches, stems and roots of 2 to 11-yr-old red pine trees(Pinus densiflora) were examined and applied to Thornley's growth equation, $$R=(\frac{1-Yg}{Yg})\frac{dW}{dt}+mW$$. The conversion efficiency of substrates(Yg), maintenance respiration coefficients(m), relative growth rates(${\mu}$) were estimated. The efficiency of conversion of substrates (Yg) was 0.3637g/g dw/yr and the maintenance respiration coefficient(m0 was 0.094g/g dw/yr. The relative growth rate(${\mu}$) was remarkably reduced with age from 0.90(2-year-old) to 0.33:11 year-old). The Ratio of gross respiration(R) per gross photosynthesis(Pg), R/Pg showed the range of 0.6~0.7 and annually 64% of Pg was spent for constructive respiration. The 3.4% of dry weight of whole tree was spent for maintenance respiration.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.505-511
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• 1994

Seeds of Rigitaeda pine tree(Pinus rigida${\times}$P. taeda) was primed with polyethylene glycol(PEG-6000) under different PEG concentrations, treatment period, and temperatures to test uniformity of germination. Coated seeds and PEG treated seeds were sown to compare germination, emergence, establishment, and seedling growth. The results obtained are summarized as follows : 1. As the concentration of PEG increased, as total germination percentage of pine tree was increased. Total germination percentage of pine tree seeds primed with PEG at 15 or $20^{\circ}C$ was better than the seeds treated at $10^{\circ}C$ compared to untreated seeds. 2. Germination rate was improved as primed period long and level of PEG concentration high. 3. Maximum germination rate was high with long PEG treatment period, and markedly improved when the seeds were primed at $20^{\circ}C$ 4. Priming with PEG at $20^{\circ}C$ for 12 days reduced time taken for germination. 5. Osmoconditioned seeds accelerated germination under drought condition with injurious effect of coated seeds by some chemicals. 6. There were much differences in establishment and dry matter production between drill and oversowing method, and primed seeds showed better performances than the coated seeds. Coating effects to seeds were better under drought soil condition rather than moderate moisture condition.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.6
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• pp.823-828
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• 2012

Texture and descriptive sensory characteristics of a Korean rice cake (Karedduk) with added mixtures of fructooligosaccharide (95%) and emulsifier, Sodium Stearoyl Lactylate-90 (SSL-90), were investigated after 2 and 24 hr of storage at $5^{\circ}C$. A central composite design was used for the arrangement of treatment. Different levels of fructooligosaccharide (95%), 0, 3, 6, 9, and 12%, were added to dry rice flour. Also, different levels of emulsifier, 0, 0.3, 0.6, 0.9, and 1.2%, were added to the same dry rice flour. The texture properties analysis using a Texture Analyzer revealed that the chewiness, gumminess, and hardness were significantly different. The effect of retarding retrogradation of Korean rice cakes (Karedduk) with added mixtures of fructooligosaccharide (95%) and SSL-90 showed an increasing trend as the amount of fructooligosaccharide (95%) increased. Overall, the instrumental texture properties were highly correlated with the sensory characteristics. The results suggested that Korean rice cakes (Karedduk) with the addition of a mixture of fructooligosaccharide (95%) and SSL-90 can be made from the mixture of 9% fructooligosaccharide (95%) and 0.9% SSL-90 in order to retard starch retrogradation.

• Journal of IKEEE
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• v.24 no.3
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• pp.859-866
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• 2020

This paper proposes a 2-ch DC-DC converter with a wide-input voltage range from 2.9V~5.6V for wearable AMOLED displays. For positive voltage V_POS, a boost converter is designed using an over-charged voltage permissible circuit (OPC) which generates a normal output voltage even if over-input voltage is applied, and a SPWM-PWM dual mode with 3-segmented power transistors to improve efficiency at light load. For negative voltage V_NEG, a 0.5x regulated inverting charge pump is designed to increase power efficiency. The proposed DC-DC converter was designed using a 0.18-㎛ BCDMOS process. Simulation results show that the proposed DC-DC converter generates V_POS voltages of 4.6 V and V_NEG voltage of -0.6V~-2.3V for input voltage of 2.9V to 5.6V. In addition, it has power efficiency of 49%~92%, output ripple voltage has less than 20 mV for load current range of 1 mA~70 mA.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.536-542
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• 2000

임상에서 점차 Mineral Trioxide Aggregate (MTA)에 대한 우수성이 소개되면서, apical matrix로의 사용은 주목할 만하다 할 수 있다. 본 연구의 목적은 개방형근관에서 MTA가 apical matrix로 사용될 때의 치근단 밀폐효과를 알아 보고, 근관충전의 시기와 matrix의 두께가 치근단 밀폐에 미치는 영향을 치근단 미세누출의 측면과 matrix탈락빈도의 측면에서 관찰하고자 하는 것이다. 개방형 근관을 재현하고자 45개의 발거된 단근치에 #90크기로 근단공을 형성하였고, 투명레진등을 이용하여 치근단 병소를 갖는 치조골을 재현한 후, 4개의 실험 군과 1개의 대조 군으로 분류하였다. A군: 2mm두께의 MTA matrix 형성후, 열연화된 Gutta-percha와 AH26 sealer를 이용하여 즉시 근관충전. B군: 2mm 두께의 MTA matrix 형성후, A군과 같은 방법으로 24시간 후 근관충전. C군: 4mm 두께의 MTA matrix 형성후, A군과 같은 방법으로 즉시 근관충전. D군: 4mm 두께의 MTA matrix 형성후, A군과 같은 방법으로 24시간 후 근관충전. 대조군: matrix를 사용하지 않고 열연화된 Gutta-percha와 AH26 sealer를 이용하여 근관충전하였다. Matrix의 탈락이 있는 경우 기록하고 완전 수세 후 다시 시행하였다. 색소침투정도의 평가를 위해 methylene blue에 치아를 48시간 침수시킨 후 협설로 양분하였다. 각 시편들을 고배율 현미경 관찰 후 비디오촬영 하였고, digitalized image analysing program을 이용하여 두명의 관찰자가 누출의 정도를 평가한 후, One-way ANOVA로 통계적 유의성을 검증하여 다음과 같은 결과를 얻었다. 1. Matrix를 사용한 실험 군이 matrix를 사용하지 않은 대조 군에 비해 유의성 있게 낮은 누출을 보였다(p<0.05). 그러나 근관충전시기와 matrix의 두께를 달리한 실험군 내에서는 누출에 유의성 있는 차이가 나타나지 않았다. 2. 모든 실험군에서 gutta-percha를 이용한 근관충전의 시기에 matrix탈락 및 gutta-percha의 압출은 발생하지 않았다.

• The KIPS Transactions:PartB
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• v.10B no.6
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• pp.657-664
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• 2003

Reliable tracking of moving humans is essential to motion estimation, video surveillance and human-computer interface. This paper presents a new approach to human motion tracking that combines appearance-based and model-based techniques. Monocular color video is processed at both pixel level and object level. At the pixel level, a Gaussian mixture model is used to train and classily individual pixel colors. At the object level, a 3D human body model projected on a 2D image plane is used to fit the image data. Our method does not use inverse kinematics due to the singularity problem. While many others use stochastic sampling for model-based motion tracking, our method is purely dependent on nonlinear programming. We convert the human motion tracking problem into a nonlinear programming problem. A cost function for parameter optimization is used to estimate the degree of the overlapping between the foreground input image silhouette and a projected 3D model body silhouette. The overlapping is computed using computational geometry by converting a set of pixels from the image domain to a polygon in the real projection plane domain. Our method is used to recognize various human motions. Motion tracking results from video sequences are very encouraging.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.11_12
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• pp.557-565
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• 2005

This paper presents the development and implementation of a zero-copy file transfer mechanism that improves the efficiency of file transfers for PC cluster systems using hardware-based VIA(Virtual Interface Architecture) network adapters. VIA is one of the representative user-level communication interfaces, but because there is no library for file transfer, one copy occurs between kernel buffer and user boilers. Our mechanism presents a file transfer primitive that does not require the file system to be modified and allows the NIC to transfer data from the kernel buffer to the remote node directly without copying. To do this, we have developed a hardware-based VIA network adapter, which supports the PCI 64bit/66MHz bus and Gigabit Ethernet, as a NIC, and implemented a zero-copy file transfer mechanism. The experimental results show that the overhead of data coy and context switching in the sender is greatly reduced and the CPU utilization of the sender is reduced to $30\%\~40\%$ of the VIA send/receive mechanism. We demonstrate the performance of the zero-copy file transfer mechanism experimentally. and compare the results with those from existing file transfer mechanisms.