• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.10a
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• pp.243.3-244
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• 1979

Low molecular weight endo-glucanase fraction of cellulase from Trichoderma reesei was purified using Sephadex G-100 and concanavalin A-Sepha-rose 4B affinity chromatography. Its biochemical characteristics including pH profile, temperature profile and kinetic behavior were studied. The optimum conditions for enzymatic reaction were pH 6.0 and $5^{\circ}C.$ The activation energy for CMC (carboxymethylcellulose) was 10,800 cal/mole. Its adsorption to amorhous and crystalline cellulose was observed. Adsorption to amorphous cellulose was more rapid and greater than that of crystalline cellulose. Reconstitution study was performed. Significance of low molecular weight endo-glucanase on cellulose hydrolysis will be further discussed.

• Ocean and Polar Research
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• v.34 no.3
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• pp.325-335
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• 2012

It is well known that sound waves in the sea propagates under the influence of sea surface and bottom roughness, the sound speed profile, the water depth, and the density of sea floor sediment. In particular, an abrupt change of sound speed with depth can greatly affect sound propagation through an eddy. Eddies are frequently generated in the East Sea near the Korean Peninsula. A warm eddy with diameter of about 150 km is often observed, and the sound speed profile is greatly changed within about 400 m of water depth at the center by the eddy around the Ulleung Basin in the East Sea. The characteristics of low-frequency sound propagation across a warm eddy are investigated by a sound propagation model in order to understand the influence of warm eddies. The acoustic rays and propagation losses are calculated by a range-dependent acoustic model in conditions where the eddy is both present and absent. We found that low-frequency sound propagation is affected by the warm eddy, and that the phenomena dominate the upper ocean within 800 m of water depth. The propagation losses of a 100 Hz frequency are variable within ${\pm}15$ dB with depth and range by the warm eddy. Such variations are more pronounced at the deep source near the sound channel axis than the shallow source. Furthermore, low-frequency sound propagation from the eddy center to the eddy edge is more affected by the warm eddy than sound propagation from the eddy edge to the eddy center.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.107-107
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• 2001

목적： 초상자성 nano-particle 조영제의 자기이완효과에 관한 out sphere 기전에 기초하여 각각의 자기장의 세기에서 T1/T2 자기이완율을 나타내는 NMRD profile을 수치적으로 simulation 하는 프로그램을 개발하고자 하였다. 대상 및 방법： 초상자성 nano-particle 조영제의 경우 초상자성 물질을 생체적합성 고분자로 표면 coating하기 때문에 상자성 조영제와는 달리 전적으로 "out sphere"기여도만을 고려하였고 또한 초상자성 물질의 경우 자기적 에너지의 크기가 매우 크기 때문에 상자성 조영제의 기전에서 사용되는 "low field"근사를 사용할 수 없으므로 Brillouin 함수로 표현되는 총자화에 대한 표현을 적용하였다. nano-particle내에 포함된 Fe 원자수에 따른 T1 및 T2 NMRD Profile과 온도에 따른 T1 및 T2 NMRD Profile 그리고 초상자성 nano-particle size에 따른 T1 및 T2 NMR Profile을 PC (CPU=800 Mhz, memory=128 MB) 환경하에서 symbolic computation tool 인 MathCad (MathCad, USA)를 사용하여 구현하였다.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.127-133
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• 2014

Purpose: Low dose of PET/CT is important because of Patient's X-ray exposure. The aim of this study was to evaluate the effectiveness of low-dose PET/ CT image through the CTAC and QAC of patient study and phantom study. Materials and Methods: We used the discovery 710 PET/CT (GE). We used the NEMA IEC body phantom for evaluating the PET data corrected by ultra-low dose CT attenuation correction method and NU2-94 phantom for uniformity. After injection of 70.78 MBq and 22.2 MBq of 18 F-FDG were done to each of phantom, PET/CT scans were obtained. PET data were reconstructed by using of CTAC of which dose was for the diagnosis CT and Q. AC of which was only for attenuation correction. Quantitative analysis was performed by use of horizontal profile and vertical profile. Reference data which were corrected by CTAC were compared to PET data which was corrected by the ultra-low dose. The relative error was assessed. Patients with over weighted and normal weight also underwent a PET/CT scans according to low dose protocol and standard dose protocol. Relative error and signal to noise ratio of SUV were analyzed. Results: In the results of phantom test, phantom PET data were corrected by CTAC and Q.AC and they were compared each other. The relative error of Q.AC profile was been calculated, and it was shown in graph. In patient studies, PET data for overweight patient and normal weight patient were reconstructed by CTAC and Q.AC under routine dose and ultra-low dose. When routine dose was used, the relative error was small. When high dose was used, the result of overweight patient was effectively corrected by Q.AC. Conclusion: In phantom study, CTAC method with 80 kVp and 10 mA was resulted in bead hardening artifact. PET data corrected by ultra- low dose CTAC was not quantified, but those by the same dose were quantified properly. In patients' cases, PET data of over weighted patient could be quantified by Q.AC method. Its relative difference was not significant. Q.AC method was proper attenuation correction method when ultra-low dose was used. As a result, it is expected that Q.AC is a good method in order to reduce patient's exposure dose.

• Hip & pelvis
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• v.30 no.4
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• pp.219-225
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• 2018

Purpose: Ischiofemoral impingement (IFI)-primarily diagnosed by magnetic resonance imaging (MRI)-is an easily overlooked disease due to its low incidence. The purpose of this study was to evaluate the usefulness of false profile view as a screening test for IFI. Materials and Methods: Fifty-eight patients diagnosed with IFI between June 2013 and July 2017 were enrolled in this retrospective study. A control group (n=58) with matching propensity scores (age, gender, and body mass index) were also included. Ischiofemoral space (IFS) was measured as the shortest distance between the lateral cortex of the ischium and the medial cortex of lesser trochanter in weight bearing hip anteroposterior (AP) view and false profile view. MRI was used to measure IFS and quadratus femoris space (QFS). The receiver operating characteristics (ROC), area under the ROC curve (AUC) and cutoff point of the IFS were measured by false profile images, and the correlation between the IFS and QFS was analyzed using the MRI scans. Results: In the false profile view and hip AP view, patients with IFI had significantly decreased IFS (P<0.01). In the false profile view, ROC AUC (0.967) was higher than in the hip AP view (0.841). Cutoff value for differential diagnosis of IFI in the false profile view was 10.3 mm (sensitivity, 88.2%; specificity, 88.4%). IFS correlated with IFS (r=0.744) QFS (0.740) in MRI and IFS (0.621) in hip AP view (P<0.01). Conclusion: IFS on false profile view can be used as a screening tool for potential IFI.

• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.10-14
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• 2015

This paper reports the results of a study on the optimization of the etching profile, which is an important factor in deep-reactive-ion etching (DRIE), i.e., dry etching. Dry etching is the key processing step necessary for the development of the Internet of Things (IoT) and various microelectromechanical sensors (MEMS). Large-area etching (open area > 20%) under a high-frequency (HF) condition with nonoptimized processing parameters results in damage to the etched sidewall. Therefore, in this study, optimization was performed under a low-frequency (LF) condition. The HF method, which is typically used for through-silicon via (TSV) technology, applies a high etch rate and cannot be easily adapted to processes sensitive to sidewall damage. The optimal etching profile was determined by controlling various parameters for the DRIE of a large Si wafer area (open area > 20%). The optimal processing condition was derived after establishing the correlations of etch rate, uniformity, and sidewall damage on a 6-in Si wafer to the parameters of coil power, run pressure, platen power for passivation etching, and $SF_6$ gas flow rate. The processing-parameter-dependent results of the experiments performed for optimization of the etching profile in terms of etch rate, uniformity, and sidewall damage in the case of large Si area etching can be summarized as follows. When LF is applied, the platen power, coil power, and $SF_6$ should be low, whereas the run pressure has little effect on the etching performance. Under the optimal LF condition of 380 Hz, the platen power, coil power, and $SF_6$ were set at 115W, 3500W, and 700 sccm, respectively. In addition, the aforementioned standard recipe was applied as follows: run pressure of 4 Pa, $C_4F_8$ content of 400 sccm, and a gas exchange interval of $SF_6/C_4F_8=2s/3s$.

• KIPE Magazine
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• v.27 no.4
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• pp.68-75
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• 2022

• Journal of the Korean Society of Combustion
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• v.8 no.4
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• pp.9-14
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• 2003

High temperature air combustion technology has been utilized by using preheated air over 1100 K and excessive exhaust gas recirculation. Numerical analysis was performed to investigate the combustion characteristics with high temperature deficient oxygen air combustion by adopting a counterflow as a model problem accounting for detailed chemical kinetics. Methane($CH_4$) was used as a test fuel and calculated oxidizer conditions were low temperature high oxygen (300K, $X_{O2}=0.21$) and high temperature low oxygen (1300K, $X_{O2}=0.04$) conditions. The latter case showed that the flame temperature is lower than the former case and its profile showed monotonic decrease from oxidizer to fuel side, without having local maximum flame temperature at high stretch rate. Also, heat release rate was one order lower and it has one peak profile because of low oxygen concentration and heat release rate integral is almost same for stretch rate. High temperature low oxygen air combustion shows low NO emission characteristics.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.202-207
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• 2017

This paper presents the performance of a planar, low-profile, and wide-gain-bandwidth leaky-wave slit antenna in different thickness values of high-permittivity gallium arsenide substrates at terahertz frequencies. The proposed antenna designs consisted of a periodic array of $5{\times}5$ metallic square patches and a planar feeding structure. The patch array was printed on the top side of the substrate, and the feeding structure, which is an open-ended leaky-wave slot line, was etched on the bottom side of the substrate. The antenna performed as a Fabry-Perot cavity antenna at high thickness levels ($H=160{\mu}m$ and $H=80{\mu}m$), thus exhibiting high gain but a narrow gain bandwidth. At low thickness levels ($H=40{\mu}m$ and $H=20{\mu}m$), it performed as a metasurface antenna and showed wide-gain-bandwidth characteristics with a low gain value. Aside from the advantage of achieving useful characteristics for different antennas by just changing the substrate thickness, the proposed antenna design exhibited a low profile, easy integration into circuit boards, and excellent low-cost mass production suitability.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.4
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• pp.588-597
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• 2007

Low-fat ground pork patties, LFGPP (<10% total fat) formulated with 0.1, 0.2 and 0.3 percent sodium alginate (SA) were processed and compositional, processing and sensory characteristics were compared with control patties containing 20% fat. The moisture content of raw and cooked LFGPP were significantly (p<0.05) higher than control patties because of greater amount of added water in the formulation. The cooking yield, moisture and fat retention also increased linearly in different treatments of LFGPP. The dimensional parameters such as gain in height, decrease in diameter and shrinkage were significantly (p<0.05) lower in LFGPP in comparison to control. Amongst the sensory attributes, flavour showed a declining trend with the increase in concentration of SA in LFGPP. However, low-fat patties with 0.1% SA rated similar to high-fat control. The lipid profile revealed 49.78 and 43.22% decrease in total lipids and cholesterol content respectively, compared to control. The calorie content was reduced significantly (p<0.05) in LFGPP. The texture profile of LFGPP with 0.1% SA was similar to that of high-fat control. The LFGPP remained stable without any appreciable loss of physico-chemical, microbiological and organoleptic quality during refrigerated storage ($4{{\pm}}1^{\circ}C$) for 21 and 35 days in aerobic and vacuum packaging respectively.