• Journal of Korea Soil Environment Society
• /
• v.2 no.3
• /
• pp.81-88
• /
• 1997

The purpose of this study is to assess contaminant transfer and environmental impacts to the surroundings by inadequate control of USTs. Several methodologies can be used in sampling procedure for the site assessment depending on the appearance of contaminants on the site and their types. In this case study because of site contaminants, randomized and/or triangle matrix techniques were used. As a result, the composition of materials in OO gas station were appeared in several status. From 1 to 2.5m depth, the soil was composed of silty sand and gravel, around 4m depth, weathered rock was appeared. Based on the preliminary and actual site investigation by DPT methodologies on the width and depth of the site with analysis of BTEX and TPH, no contamination was found in OO gas station, however, in one point because of careless dumping after refill by oil company, about 1731. 5 ppm of TPH appeared.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.1 s.343
• /
• pp.143-148
• /
• 2006

This paper presents a high isolation and power-handling single-pole double-throw(SPDT) switch for dual band wireless LAN applications. The switch circuit has asymmetric topology which uses stacked-gate to have high power-handling and isolation for the Tx path. The proposed SPDT switch has been designed with optimum gate-width, bias, and number of stacked-gate FET. This SPDT switch has been implemented with $0.25{\mu}m$ GaAs pHEMT process which has Gmmax of 500mS/mm and fmax of 150GHz. The designed SPDT switch has the measured insertion loss of better than 0.9dB and isolation of better than 40dB for the Tx path and 25dB for the Rx path and the high power handling capability with PldB of about 23dBm for control voltage of -3/0V. The fabricated SPDT switch chip size is $1.8mm{\times}1.8mm$.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.4
• /
• pp.31-37
• /
• 2000

In the case of metal-induced lateral crystallization (MILC) for low temperature poly-Si TFT, offset length between Ni-thin film and the sides of gate could be modified to control the location of MILC boundary. Electrical characteristics were compared to analyze the effect of MILC boundary that was located either in or out of the channel region of the TFT. By removing the MILC boundary from channel region, on current, subthreshold slope and leakage current properties could be improved. When MILC boundary was located in the channel region, leakage current was reduced with electrical stress biasing. The amount of reduction increased as the channel width increased, but it was independent of the channel length.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.11
• /
• pp.1121-1129
• /
• 2009

In this paper, the UWB(Ultra-Wide Band) modules such as a pulse generator and the LNA(Low-Noise Amplifier) with AGC(Auto Gain Control) are designed to construct a cross-borehole pulse radar system, of which performance is compared with the existing system. The budget and specification of the radar system are determined by calculating the total path loss of the underground medium including an empty cavity. The pulse generator is fabricated to have the repeatation frequency 40 kHz, the pulse width lower than 5 ns and the peak signal level +73 dBm. The UWB LNA is designed to have the noise figure 3.77 dB, the variable gain range 100 dB and the frequency range of 20 MHz to 200 MHz. Compared with the existing system in an actual test site, the implemented system renders it possible to detect the blind area due to the UWB LNA with low noise figure.

• The Journal of Korean Academy of Prosthodontics
• /
• v.27 no.2
• /
• pp.53-78
• /
• 1989

This study was taken to observe the changes of the residual stress in the alloy and to measure 3 dimensional distortions of the long span ceramo-metal bridge. The materials used in this study were Pors-on 4 (Pd-Ag alloy), and Ceramco and Vita VMK 68 powders. The residual stress of the alloy was measured on the six specimens (dia. 8m/m) by the X-ray diffraction stress analyzer according to the kind of ceramic powder and different measuring stages. And, for the measurement of the distortions, fifteen specimens of the anterior 8-unit ceramo-metal brige were fabricated and subjected to the 3-D coordinate measuring machine. Variables included the 2 kinds of a ceramic powder and the presence or absence of a splint bar at the cast metal framework. The measuring stages in both were after casting, after degassing and after glazing. The following conclusions were obtained : 1. The residual stress of the alloy showed increasing tendency for the tension by the ceramic fusing, but there was not significance. 2. The tendency of the distortions in the cast metal frameworks were decrease of the width, the anterior displacement and sagging. 3. The amount of the distortions at the degassing stage were greater than that at the ceramic fusing stage. 4. The splint bar was effective to control the distortion only at ceramic fusing stage. 5. The sagging distortion in the Ceramco firing were even through all measuring stages, but in the Vita firing, pronounced at degassing stage.

• Journal of Periodontal and Implant Science
• /
• v.47 no.3
• /
• pp.165-173
• /
• 2017

Purpose: The aim of this study was to radiographically and clinically compare the effect of extracellular matrix (ECM) membranes on dimensional alterations following a ridge preservation procedure. Methods: One of 2 different ECM membranes was applied during a ridge preservation procedure. A widely used ECM membrane (WEM; Bio-Gide, Geistlich Biomaterials, Wolhusen, Switzerland) was applied in the treatment group and a newly developed ECM membrane (NEM; Lyso-Gide, Oscotec Inc., Seongnam, Korea) was applied in the control group. Cone-beam computed tomography (CBCT) scans and alginate impressions were obtained 1 week and 6 months after the ridge preservation procedure. Results were analyzed using the independent t-test and the nonparametric Mann-Whitney U test. Results: There were no significant differences between the ECM membranes in the changes in the dimension, width, and height of the extraction socket or the quantity of bone tissue. Conclusions: The NEM showed comparable clinical and radiographic results to the WEM following the ridge preservation procedure.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.13
• /
• pp.5159-5162
• /
• 2015

Background: Chronic myeloproliferative diseases are clonal stem cell diseases which occur as a result of uncontrollable growth and reproduction of hematopoietic stem cells, which are the myeloid series source in bone marrow. Recent studies have suggested that chronic inflammation can be a triggering factor in the clonal change in chronic myeloproliferative neoplasia (CMPN). In our study, we evaluated the existence of a chronic inflammation process in our Philadelphia negative (Ph-)CMPN patients using inflammation parameters in combination with demographic, laboratory and clinical characteristics of the patients. Materials and Methods: Demographic characteristics, clinical and laboratorial data, and thrombosis histories of 99 Ph-CMPN patients, who were diagnosed at our outpatient clinic of hematology in accordance with WHO 2008 criteria, were analyzed retrospectively,with 80 healthy individuals of matching gender and age included as controls. Complete blood counts, sedimentation, C reactive protein (CRP), JAK V617F gene mutations, abdomen ultrasound images and previous thrombosis histories of these patients were retrospectively analyzed. Results: Ph-CMPN and healthy control groups included 99 and 80 cases, respectively. PV, ET and MF diagnoses of patients were 43 (%43.4), 44 (44.4%) and 12 (12.1%), respectively. JAK V617F gene mutation was found to be positive in 64 (71.1%) of all cases and in 27(65.8%), 32 (82%), 5 (50%) of the cases in PV, ET and PMF groups, respectively. Thrombosis was determined as 12 (12%) in the entire group, 12.5% in the JAK V617F negative and 15.3% in the positive patients, with no statistical significance (p=0.758). No significant difference was observed between patients with and without previous thrombosis history in respect to hemogram parameters, sedimentation and CRP (p>0.05), neutrophil to lymphocyte ratio (NLR), erythrocyte distribution width (RDW), mean platelet volume (MPV) and sedimentation levels of the patient.

• Composites Research
• /
• v.28 no.5
• /
• pp.249-253
• /
• 2015

This paper reports a study on a method for achieving lightweight thermoplastic laminate composites referred to as tow spreading technology. Thickness of an unspread 12 K carbon fiber tow is reduced by increasing the tow width from 7 mm to 20 mm. The polypropylene (PP) film was used to stabilize and impregnate the spread tow, covering it into a partially consolidated prepreg: 12 K carbon fiber spread tow/PP. Laminates were fabricated from the spread tow prepreg and control laminate composites were produced from unspread tow prepreg consisting of 12 K carbon fiber and PP. The void content, tensile and flexural properties of the composite laminates were investigated. Consequently, the spread tow laminate composite exhibited lower void content and improved mechanical properties.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.6
• /
• pp.785-791
• /
• 2000

GDI (Gasoline Direct Injection) engines are considered as one of the candidates for next generation engines of passenger cars, which reduce exhaust emissions and fuel consumption. In GOI engines, a high-pressure gasoline supply system is required to directly inject the fuel to combustion chambers. Because of low lubricity of gasoline fuel, the clearance between a plunger and a barrel in GDI fuel pumps is too wide to achieve smooth hydrodynamic lubrication. Thus, it is difficult to generate high-pressure condition in GDI fuel pump since large amount of leakage flow occurs between the plunger and the barrel In this study, an optimum plunger design is presented to minimize leakage in the aspect of flow control. This paper analyzes leakage flow characteristics in the clearance to improve pumping performance of GDI fuel pumps. Effects of groove in the plunger are studied according to variations of depth and width. Evaluations of pumping performance are determined by the amount of pressure drop in the leakage path assuming a constant leakage flows. Both of turbulence and incompressible models are introduced in CFD (Computational Fluid Dynamics) analysis. Design parameters have been introduced to minimize leakage in limited space, and a methodological study on geometrical optimization has been conducted. As results of CFD analysis in various geometrical cases, optimum groove depths have been found to generate maximum sealing effects on gasoline fuel between the plunger and the barrel. This procedure offers a methodological way of an enhancement of plunger design for high-pressure GDI fuel pumps.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.1
• /
• pp.25-31
• /
• 2000

In this paper, we proposed an algorithm that used a direct method to set an initial value of Broydon-Fletcher-Goldfarb-Shanno(BFGS) method and, accordingly, conducted an experiment in optimal directivity synthesis of adaptive ultrasonic transducer by point source array. To certify the efficiency of this method, quasi-ideal beam with arbitrary beam width, rotating beam, and multi beam, all with the limited side lobe level -30dB, were chosen to check the problem of directivity synthesis that was formed by point source array in the second dimensional sound field. The numerical calculation results showed that the proposed method performed the directivity synthesis faster than the BFGS method did. In addition, the proposed method showed a good error correction for directivity synthesis, and did not demand the choice of initial value. Finally, it is also shown that the proposed method can be used for the adaptive control that was not possible with the direct method alone.