• Design & Manufacturing
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• v.14 no.2
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• pp.56-61
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• 2020

Recently, research for machining next-generation micro semiconductor processes and micro patterns has been actively conducted. In particular, it is applied to various industrial fields depending on the machining method in the case of FIB (Focused ion beam) milling. In this study, intends to deal with FIB milling machining technology for ultra-precision diamond tool fabrication technology. Ultra-precision diamond tools require nano-scale precision, and FIB milling is a useful method for nano-scale precision machining. However, FIB milling has a problem of Gaussian characteristics that are differently formed according to the beam current due to the input of an ion beam source, and there are process conditions to be considered, such as a side clearance angle problem of a diamond tool that is differently formed according to the tilting angle. A series of process steps for fabrication a ultra-precision diamond tool were studied and analyzed for each process. It was confirmed that the effect on the fabrication process was large depending on the spot size of the beam and the current of the beam as a result of the experimental analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.982-989
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• 2013

Omni-directional antennas of UHF-Band are located on the top and bottom side of the Smart UAV in order to connect a link always. Therefore one of each antennas should be connected to a ground antenna. Because the communication link of the omni-directional antennas is influenced by the objectives around aircraft, the clearance of LOS(Line of Sight) should be achieved in order to avoid a loss of link. In this paper, the analysis results on the influence of the complex objectives placed around the antenna on the communication link are presented according to the change of attitude angles. The best positions of antennas are selected based on the electromagnetic analysis using XGTD tool which supports the modeling of antenna pattern. The flight tests of the Smart UAV were successfully performed with the selected antenna position.

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.172-179
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• 1998

Valve lifter namely tappet is supported by lifter hole which is located upper side of camshaft in cylinder block transforms rotatic mvement of camshaft into linear movement and helps to open and shut the en-gine valve as an engine parts. The face of valve lifter which is continuously contacting with camshaft brings about abnormal wears such as unfair wear and early wear because it is severely loaded in the valve train system. These wears act as a defect like over-clearance and cause imperfect combustion of fuel during the valve lifting in the combustion chamber. Consequently this imperfect combustion makes the engine out-put decrease and has cause on air pollution. To prevent these wears therefore The valve lifter cast in me-tal developed into SiC ceramics valve lifter which has an excellence in wear and impact resistance As a results the optimum process conditions like injection condition mixture ratio and debonding process could be established. After sintering fine-sinered dual microstructure in which prior ${\alpha}$-SiC matches well with new SiC(${\beta}$-SiC) produced by reaction among the ${\alpha}$-SiC carbon and silicon was obtained. Based on the study it is verified that mechanical properties of SiC valve lifter are excellent in Vickers hardness 1100-1200 bending strength (300-350 Pa) fracture toughness(1.5-1.7 Mpa$.$m1/2) Through engine dynamo test-ing SiC valve lifter and metal valve lifter are examined and compared into abnormal phenomena such as early fracture unfair and early wear. It is hoped that this research will serve as an important springboard for the future study of heavy duty diesel engine parts developed by ceramics which has a good wear resis-tance relaibility and lightability.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.3
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• pp.1117-1122
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• 2015

Background: Cisplatin is still used as a first-line medication for solid tumors. Nephrotoxicity is a serious side effect that can decrease renal function and restrict applicable doses. This research aimed to obtain the profile of cisplatin-induced nephrotoxicity and its associated factors in adult cancer patients at Dharmais National Cancer Hospital (DNCH). Materials and Methods: The design was cross-sectional with data obtained from patient medical records. We retrospectively reviewed adult cancer patients treated with cisplatin ${\geq}60mg/m^2$ for at least four consecutive chemotherapy cycles from August 2011 to November 2013. The nephrotoxicity criterion was renal function decline characterized by creatinine clearance <60 ml/min using the Cockroft-Gault (CG) equation. Results: Eighty-eight subjects received at least four chemotherapy cycles of cisplatin. The prevalence of cisplatin nephrotoxicity was 34.1%. Symptoms could be observed after the first cycle of chemotherapy, and the degree of renal impairment was higher with increased numbers of cycles (r=-0.946, $r^2=89.5%$). Factors that affected the decline of renal function were patient age (p=0.008, OR=3.433, 95%CI= 1.363-8.645) and hypertension (p=0.026, OR=2.931, 95%CI=1.120-7.670). Conclusions: Cisplatin nephrotoxicity occurred in more than one-third of patients after the fourth cycle of chemotherapy and worsened after each cycle despite preventive strategies such as hydration. The decline of renal function induced by cisplatin ${\geq}60mg/m^2$ was affected by age and hypertension.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.446-456
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• 2006

The effect of relative position of the stationary turbine blade for the fixed vane has been investigated on blade tip and shroud heat transfer. The local mass transfer coefficients were measured on the tip and shroud fur the blade fixed at six different positions within a pitch. A low speed stationary annular cascade with a single turbine stage was used. The chord length of the tested blade is 150 mm and the mean tip clearance of the blade having flat tip is 2.5% of the blade chord. A naphthalene sublimation technique was used for the detailed mass transfer measurements on the tip and the shroud. The inlet flow Reynolds number based on chord length and incoming flow velocity is fixed to $1.5{\times}10^5$. The results show that the incoming flow condition and heat transfer characteristics significantly change when the relative position of the blade changes. On the tip, the size of high heat/mass transfer region along the pressure side varies in the axial direction and the difference of heat transfer coefficient is up to 40% in the upstream region of the tip because the position of flow reattachment changes. On shroud, the effect of tip leakage vortex on the shroud as well as tip gap entering flow changes as the blade position changes. Thus, significantly different heat transfer patterns are observed with various blade positions and the periodic variation of heat transfer is expected with the blade rotation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.4 s.235
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• pp.495-503
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• 2005

Experiments were conducted in a low speed stationary annular cascade to investigate local heat transfer characteristics on the tip and shroud and the effect of inlet Reynolds number on the tip and shroud heat transfer. Detailed mass transfer coefficients on the blade tip and the shroud were obtained using a naphthalene sublimation technique. The turbine test section has a single stage composed of sixteen guide vanes and blades. The chord length and the height of the tested blade are 150 mm and about 125 mm, respectively. The blade has flat tip geometry and the mean tip clearance is about $2.5{\%}$of the blade chord. The inlet flow Reynolds number based on chord length and incoming flow velocity is changed from $1.0{\times}10^{5}\;to\;2.3{\times}10^{5}.$ to investigate the effect of Reynolds number. Flow reattachment after the recirculation near the pressure side edge dominates the heat transfer on the tip surface. Shroud surface has very intricate heat/mass transfer distributions due to complex flow patterns such as acceleration, relaminarization, transition to turbulent flow and tip leakage vortex. Heat/mass transfer coefficient on the blade tip is about 1.7 times as high as that on the shroud or blade surface. Overall averaged heat/mass transfer coefficients on the tip and shroud are proportional to $Re_{c}^{0.65}\;and\;Re_{c}^{0.71},$ respectively.

• The Journal of Internal Korean Medicine
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• v.40 no.5
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• pp.974-982
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• 2019

Objective: Modern medicine offers no efficient way to clear colonization by vancomycin-resistant enterococci (VRE). However, VRE decolonization needs to be cleared as soon as possible to prevent VRE transmission. This study reports six cases in which the duration of vancomycin resistant enterococcus (VRE) colonization was reduced by Bojungikki-tang-gami. Methods: Six inpatients with VRE colonization were administered Bojungikki-tang-gami and continuously followed up with cultures. After three negative stool cultures, the patients were declared cleared of VRE colonization. We recorded the duration of VRE colonization. Results: The duration of VRE colonization in the six patients was a mean of 58 days and a median of 45 days. This was shorter than the duration reported in most previous studies. No side effects were noted. Conclusions: The findings of this study suggest that Bojungikki-tang-gami might be effective in shortening the duration of VRE colonization.

• Journal of Physiology & Pathology in Korean Medicine
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• v.37 no.2
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• pp.30-35
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• 2023

Bisphosphonates, estrogen, and calcium supplements are commonly used medications for postmenopausal osteoporosis, but they are associated with various side effects such as vaginal bleeding, deep vein thromembolism, and breast cancer. In this study, we aimed to investigate the potential of a compound isolated from the roots of Oryza sativa L. to improve osteoporosis using an ovariectomized mouse model. We isolated and identified oryzativol A, a lignan compound, through chemical analysis of an ethanol extract using a bioassay-guided fractionation protocol. We also examined the metabolism, clearance, and CYP enzyme activity of oryzativol A, and found that it showed plasma stability of over 80% at all analysis times, and indicating a low likelihood of inactivation or excretion by the CYP3A4 enzyme. Our results showed that the high-dose group of oryzativol A exhibited a significant increase in bone mineral density compared to the control group. Although the ALP concentration did not differ significantly compared to the control group, it showed a tendency to increase in the high-dose group of oryzativol A. Furthermore, the abnormal ratio of serum Ca/P, caused by osteoporosis, was improved to a level closer to that of the normal group as the dosage of oryzativol A increased. Taken together, these findings suggest that oryzativol A is stable in vivo and has potential as a therapeutic agent for osteoporosis, particularly when administered in high doses.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.305-311
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• 2012

With the rapid deployment of hipass$^{(R)}$, the congestion is inevitable due to the operation of the hipass lane system. Recently, SMART Highway project have developed a multi-lane mainline tolling system, called SMART Tolling system. To analyze the effectiveness of the system in terms of capacity, this study tries to estimate the capacity and its improvement of multi-lane tolling system based on current hipass$^{(R)}$ data. The methodology uses the saturation time headway. This follows three steps; 1) estimate the saturation time headway, using hipass$^{(R)}$ data, and capacity. 2) estimate two factors (the first one is dividing the one side lane width and lateral clearance factor ($f_w$) into two side one, the second one is dividing the capacity of hipass lane operating a circuit breaker into the capacity of hipass lane not operating, the last one is increasing factor of lane width). 3) calculate the capacity of multi-lane mainline tolling system. The results of method produced 2172~2187 veh/hour as smart tolling capacities, respectively. Those are higher about 370 veh/hour than the values from existing literature reviews. Additionally, saturation time headways were identified as lower by 0.5 seconds/veh than existing headways based on hi-pass$^{(R)}$ based one, which naturally implies the improvement in capacity. Some limitations and future research agenda have also been discussed.

• Childhood Kidney Diseases
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• v.9 no.2
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• pp.159-166
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• 2005

Purpose : Recently the merits of 6 weeks of initial prednisolone treatment for pediatric primary nephrotic syndrome have been reported, and the use of the 6 week regimen is increasing. We compared our experiences with the 6 week treatment versus the 4 week treatment for Korean patients. Methods : We conducted a retrospective analysis of 69 children who had primary nephrotic syndrome and who were followed up for at least 12 months in the 4 major medical centers in Daegu. The remission rate, the relapse rate, the frequency of relapse and complication of steroid treatment were compared between the 4 weeks and 6 weeks treatment group. Results : Of the 69 children, 42 were in the 4 week treatment group and 27 were in the 6 week group. The median age, blood pressure, serum total protein, serum albumin, cholesterol, creatinine, estimated creatinine clearance, 24 hour urine protein and 12 month cumulative dose did not differ between the two groups. Among the children who relapsed after steroid treatment, the relapse time was significantly later for the 6 week treatment group. The relapse rate after 1 year of treatment was 62$\%$ in the 4 week treatment group and 52$\%$ in the 6 week treatment group; however, there was no statistically significant difference between the two groups. The frequency of relapse at 12 months was $1.5{\pm}1.2$ times in the 4 week treatment group and $1.1{\pm}1.2$ times in the 6 week treatment group, and there was not different between the two groups. The most common side effects of steroid treatment were an increase of appetite and a cushingoid appearance, and there was no statistical difference between the two groups. Among the 27 children who had kidney biopsies performed, 21 suffered from minimal change nephrotic syndrome. Conclusion : The first relapse time after steroid treatment was significantly later in the 6 week steroid treatment group. The frequency of relapse and the 12 month cumulative dose of steroid were lower in the 6 week treatment group, but there was no statistical significance between the two groups. The side effects of steroid treatment did not differ between the two groups. We need to study the long term side effects and the advanced regimens of steroid treatment in the future.(J Korea Soc Pediatr Nephrol 2005;9:159-166)