• 대한기계학회논문집B
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• 제40권4호
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• pp.227-236
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• 2016

본 논문에서는 $600{\times}600{\mu}m$ 사각 마이크로 채널에서 T자형 합류지점에서의 기체 및 액체의 주입방법이 기포 및 액체 슬러그의 생성에 미치는 영향을 실험을 통해 살펴보았다. 실험 유체로는 질소와 물을 사용하였으며, 액체 및 기체 겉보기 속도는 각각 0.05 - 1 m/s, 0.1 - 1 m/s 의 범위로 테일러 유동이 나타나는 구간에서 데이터를 얻었다. 기포 길이, 액체 슬러그 길이, 기포 속도 그리고 기포 생성 빈도를 고속 카메라를 사용하여 이미지 분석을 통해 측정하였다. 유사한 입구 겉보기 속도 조건에서, T-자형 합류지점의 main channel에 기체를 주입하는 방법(T_gas-liquid)이 액체를 주입하는 방법(T_liquid-gas)보다 기포와 액체 슬러그의 길이가 길었고 기포 생성 빈도는 낮았다. 한편, 두 주입방법에서 기포 속도는 유사하게 나타났다. T_liquid-gas 주입방법의 기존 예측 상관식은 T_gas-liquid 주입방법의 기포 길이, 기포 속도, 액체 슬러그 길이, 기포 생성 빈도 실험데이터를 각각 ~24 %, ~9 %, ~39 %, ~55 %로 예측하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1813-1817
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• 2007

The present work presents plastic limit load solutions for piping branch junctions with local wall-thinning, based on detailed three-dimensional (3-D) and small strain FE limit analyses using elastic-perfectly plastic materials. Three types of loading are considered; internal pressure, in-plane bending on the branch pipe and in-plane bending on the run pipe. The wall-tinning located on variable area of the piping branch junction is considered. A wide range of piping branch junction and wall-thinning geometries are considered. Comparison of the proposed solutions with FE results shows good agreement

• 동력기계공학회지
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• 제9권4호
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• pp.45-50
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• 2005

Characteristics of flows at T-junction duct with and without orifices are investigated in this paper. Experiments and PIV visualization were carried out for several flow rates. Two-dimensional PIV experimental apparatus was decided by numerical analysis. PIV visualization was also coded to visualize flow fields at junctions for two-dimensional case. For the PIV visualization system, Grey-Level Cross-Correlation particle tracking algorithm was used to calculate the flow fields. Vinyl chloride polymer particles of $100{\sim}150{\mu}m$ of diameter are used in this visualization. The PIV visualization results showed relatively good agreement with Experimental data.

• Progress in Superconductivity
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• 제3권1호
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• pp.83-86
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• 2001

We have fabricated a single flux quantum 4-stage shift register with interface-controlled $Y_1$$Ba_2$$Cu_3$$O_{7-x}$(YBCO) Josephson junction. The YBCO Josephson junctions showed RSJ-like current-voltage(I-V) curves at temperatures 45~80K. We tested load and shift operation of shift register with binary data sequences “1000”, “1010”, “1011”, and “1111” at 58K. For all the binary data sequences, the shift register operated successfully. By operating the circuit with proper current pulses, we observed no errors during at least 12 hours operation for all the data sequences.s.

• Journal of Korean Neurosurgical Society
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• 제38권1호
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• pp.71-73
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• 2005

A case of intramedullary spinal cord lipoma is presented. A one month-old male infant presented with irritability and weakness on his upper extremities. A magnetic resonance[MR] image of the cervical spine demonstrated a well defined, high signal intensity lesion on both T1 and T2-weighted MR images and suppression on the fat saturation sequence. The tumor mass extended from the foramen magnum to T2 vertebra level. Ventral displacement of the spinal cord with kinking of the cervico-medullary junction was evident on the T2-weighted sagittal image. Partial resection of the tumor mass through laminoplastic laminotomy from C1 to T2 resulted in improved motor weakness on his upper extremities.

• 대한본초학회지
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• 제34권2호
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• pp.25-32
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• 2019

Objectives : Gardeniae Fructus extract is used as a component of various cosmetics. However, the effect of the extract on the motility of keratinocytes has not been studied. The aim of this study is to investigate the inhibitory effect of ethanol extract of Gardeniae Fructus (GFET) or ethyl acetate extract of Gardeniae Fructus (GFEA) on oxidation and motility of human keratinocyte HaCaT cells. Methods : Antioxidant activity of Gardeniae Fructus extracts were determined by the 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay. To investigate the cytotoxicity of Gardeniae Fructus extracts, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay was performed. The mRNA expression levels of tight junction related genes were analyzed using quantitative RT-PCR analysis. Cell migration assay was employed to determine the activity of Gardeniae Fructus extracts on motility of human keratinocyte HaCaT cells. Results : GFET and GFEA showed strong antioxidant activity. GFEA showed stronger cytotoxicity in HaCaT cells than GFET until $2.0mg/m{\ell}$ concentration. Cell migration assay demonstrated that GFET and GFEA decreased the motility of HaCaT cells. In addition, the mRNA expression level of claudin 8 among tight junction genes was significantly reduced by GFET or GFEA treatment. Conclusions : We investigated the physiological activities of the extracts of Gardeniae Fructus extracts on human keratinocytes by two different extraction methods. In addition, the mRNA expression level of claudin 8 among tight junction genes was significantly reduced by either GFET or GFEA treatment. This study provides basic information on the application of Gardeniae Fructus extract to cosmetics component.

• Journal of Korean Neurosurgical Society
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• 제48권1호
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• pp.46-52
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• 2010

Objective : In cervico-thoracic junction (CTJ), the use of strong fixation device such as pedicle screw-rod system is often required. Purpose of this study is to analyze the anatomical features of C7 and T1 pedicles related to screw insertion and to evaluate the safety of pedicle screw insertion at these levels. Methods : Nineteen patients underwent posterior CTJ fixation with C7 and/or T1 included in fixation levels. Seventeen patients had tumorous conditions and two with post-laminectomy kyphosis. The anatomical features were analyzed for C7 and T1 pedicles in 19 patients using computerized tomography (CT). Pedicle screw and rod fixation system was used in 16 patients. Pedicle violation by screws was evaluated with postoperative CT scan. Results : The mean values of the width, height, stable depth, safety angle, transverse angle, and sagittal angle of C7 pedicles were $6.9{\pm}1.34\;mm$, $8.23{\pm}1.18\;mm$, $30.93{\pm}4.65\;mm$, $26.42{\pm}7.91$ degrees, $25.9{\pm}4.83$ degrees, and $10.6{\pm}3.39$ degrees. At T1 pedicles, anatomic parameters were similar to those of C7. The pedicle violation revealed that 64.1% showed grade I violation and 35.9% showed grade II violation, overall. As for C7 pedicle screw insertion, grade I was 61.5% and grade II 38.5%. At T1 level, grade I was 65.0% and grade II 35.0%. There was no significant difference in violation rate between the whole group, C7, and T1 group. Conclusion : C7 pedicles can withstand pedicle screw insertion. C7 pedicle and T1 pedicle are anatomically very similar. With the use of adequate fluoroscopic oblique view, pedicle screw can be safely inserted at C7 and T1 levels.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제32권2호
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• pp.161-167
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• 2006

Objectives: Pericoronitis was the most common indication for mandibular third molar surgery and there are no universally acceptable predictive criteria for pericoronitis occurrence. This study was designed to analyze the correlation of the pericoronitis and the eruption state of the mandibular third molar using panoramic radiographs statistically. Materials and Methods: 218 patients whose chief complaint was the extraction of the mandibular third molar were examined. The presence and absence of pericoronitis, age, sex, position of extraction site, angulation, impaction degree, position to the anterior border of mandibular ramus, distance between distal cementoenamel junction of second molar and mesial cementoenamel junction of the mandibular third molar were assessed. Then the correlation of pericoronitis and the eruption state of the mandibular third molar were analyzed by Student's t-test and chi-square test. Results: There was no correlation between Pericoronitis and age, sex, position of the mandibular third molar. The angulation(P=0.005), impaction degree(P=0.043), relation with anterior border of mandibular ramus(P=0.003), distance between distal cementoenamel junction of second molar and mesial cementoenamel junction of the mandibular third molar(P<0.05) were correlated with pericoronitis. Conclusions: The occurrence of the pericoronitis can be predicted by the eruption state of the mandibular third molar such as angulation, impaction degree, relation with anterior border of mandibular ramus, distance between distal cementoenamel junction of second molar and mesial cementoenamel junction of third molar.

• 한국전기전자재료학회논문지
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• 제14권11호
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• pp.934-940
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• 2001

Magnetic properties were investigated for Si/SiO$_2$/NiFe(300 )/A1$_2$O$_3$(t)/Co(200 ) junction related with the parameters of $Al_2$O$_3$. Insulating $Al_2$O$_3$ layer was formed by depositing a 5~40 thick Al layer, followed by a 90~120s RF plasma oxidation in an $O_2$ atmosphere. Magnetoresistance was not observed for tunnel junction with 5~10 thick Al layer, but magnetoresistance was observed large for tunnel junction with 15~40 thick Al layer. Oxidation time did not largely influence magnetoresistance. Tunnel magnetoresistance effect depended on magnetization behavior of two ferromagnetic layers. Tunneling junction was confirmed through nonlinear I-V curve. In this work, tunneling magnetoresistance(TMR) up to 30 % was observed. This apparent TMR is an artifact of the nonuniform current flow over the junction in the cross geometry of the electrodes.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.675-691
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• 2017

Jets in cross flow are of fundamental industrial importance and play an important role in validating turbulence models. Two jet configurations related to thermal fatigue phenomena are investigated: ${\bullet}$ T-junction of circular tubes where a heated jet discharges into a cold main flow and ${\bullet}$ Rectangular jet marked by a scalar discharging into a main flow in a rectangular channel. The T-junction configuration is a classical test case for thermal fatigue phenomena. The Vattenfall T-junction experiment was already subject of an OECD/NEA benchmark. A LES modelling and calculation strategy is developed and validated on this data. The rectangular-jet configuration is important for basic physical understanding and modelling and has been analyzed experimentally at CEA. The experimental work was focused on turbulent mixing between a slightly heated rectangular jet which is injected perpendicularly into the cold main flow of a rectangular channel. These experiments are analyzed for the first time with LES. The overall results show a good agreement between the experimental data and the CFD calculation. Mean values of velocity and temperature are well captured by both RANS calculation and LES. The range of critical frequencies and their amplitudes, however, are only captured by LES.