• Corrosion Science and Technology
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• 제16권3호
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• pp.100-108
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• 2017

In this investigation corrosion behavior of newly developed high-pressure die cast Al-Ni (N15) and Al-Ni-Ca (NX1503) alloys was studied in 3.5% NaCl solution. The electrochemical corrosion behavior was evaluated using open circuit potential (OCP) measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization results validated that NX1503 alloy exhibited lower corrosion current density ($i_{corr}$) value ($5.969{\mu}A/cm^2$) compared to N15 ($7.387{\mu}A/cm^2$). EIS-Bode plots revealed a higher impedance (${\mid}Z{\mid}$) value and maximum phase angle value for NX1503 than N15 alloy. Equivalent circuit curve fitting analysis revealed that surface layer ($R_1$) and charge transfer resistance ($R_{ct}$) values of NX1503 alloy was higher compared to N15 alloy. Immersion corrosion studies were also conducted for alloys using fishing line specimen arrangement to simultaneously measure corrosion rates from weight loss ($P_W$) and hydrogen volume ($P_H$) after 72 hours and NX1503 alloy had lower corrosion rate compared to N15 alloy. The addition of Ca to N15 alloy significantly reduced the Al3Ni intermetallic phase and further grain refinement may be attributed for reduction in the corrosion rate.

• IMMUNE NETWORK
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• 제12권6호
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• pp.253-260
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• 2012

${\alpha}$-Mangostin is a xanthon derivative contained in the fruit hull of mangosteen (Garcinia mangostana L.), and the administration of ${\alpha}$-Mangostin inhibited the growth of transplanted colon cancer, Her/CT26 cells which expressed Her-2/neu as tumor antigen. Although ${\alpha}$-Mangostin was reported to have inhibitory activity against sarco/endoplasmic reticulum $Ca^{2+}$ ATPase like thapsigargin, it showed different activity for autophagy regulation. In the current study, we found that ${\alpha}$-Mangostin induced autophagy activation in mouse intestinal epithelial cells, as GFP-LC3 transgenic mice were orally administered with 20 mg/kg of ${\alpha}$-Mangostin daily for three days. However, the activation of autophagy by ${\alpha}$-Mangostin did not significantly increase OVA-specific T cell proliferation. As we assessed ER stress by using XBP-1 reporter system and phosphorylation of $eIF2{\alpha}$, thapsigargin-induced ER stress was significantly reduced by ${\alpha}$-Mangostin. However, coadministration of thapsigargin with ${\alpha}$-Mangostin completely blocked the antitumor activity of ${\alpha}$-Mangostin, suggesting ER stress with autophagy blockade accelerated tumor growth in mouse colon cancer model. Thus the antitumor activity of ${\alpha}$-Mangostin can be ascribable to the autophagy activation rather than ER stress induction.

• Journal of Chest Surgery
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• 제49권4호
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• pp.287-291
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• 2016

Background: Spontaneous pneumomediastinum (SPM) is an uncommon disorder with only a few reported clinical studies. The goals of this study were to investigate the clinical manifestations and the natural course of S PM, as w ell as examine the current available treatment options for SPM. Methods: We retrospectively reviewed 91 patients diagnosed with SPM between January 2008 and June 2015. Results: The mean age of the patients was $22.7{\pm}13.2years$, and 67 (73.6%) were male. Chest pain (58, 37.2%) was the predominant symptom. The most frequent precipitating factor before developing SPM was a cough (15.4%), but the majority of patients (51, 56.0%) had no precipitating factors. Chest X-ray was diagnostic in 44 patients (48.4%), and chest computed tomography (CT) showed mediastinal air in all cases. Esophagography (10, 11.0%), esophagoduodenoscopy (1, 1.1%), and bronchoscopy (5, 5.5%) were performed selectively due to clinical suspicion, but no abnormal findings that implicated organ injury were documented. Twelve patients (13.2%) were discharged after a visit to the emergency room, and the others were admitted and received conservative treatment. The mean length of hospital stay was $3.0{\pm}1.6days$. There were no complications related to SPM except for recurrence in 2 patients (2.2%). Conclusion: SPM responds well to conservative treatment and follows a benign natural course. Hospitalization and aggressive treatment can be performed in selective cases.

• Journal of Korean Neurosurgical Society
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• 제54권4호
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• pp.289-295
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• 2013

Objective : Cerebral vasospasm is a common and potentially devastating complication of aneurysmal subarachnoid hemorrhage (aSAH). Inflammatory processes seem to play a major role in the pathogenesis of vasospasm. C-reactive protein (CRP) constitutes a highly sensitive inflammatory marker. Elevation of serum CRP levels has been demonstrated in patients with aSAH. The purpose of the current study was to evaluate the possible relationship between CRP levels in the serum and transcranial Doppler (TCD) and the development of vasospasm in patients with aSAH. Methods : A total of 61 adult patients in whom aSAH was diagnosed were included in the study from November 2008 to May 2011. The patients' demographics, Hunt and Hess grade, Fisher grade, CT scans, digital subtraction angiography studies, and daily neurological examinations were recorded. Serial serum CRP measurements were obtained on days 1, 3, 5, 7, 9, 11 and 13 and TCD was measured on days 3, 5, 7, 9, 11 and 13. All patients underwent either surgical or endovascular treatment within 24 hours of their hemorrhagic attacks. Results : Serum CRP levels peaked on the 3rd postoperative day. There were significant differences between the vasospasm group and the non-vasospasm group on the 1st, 3rd and 5th day. There were significant differences between the vasospasm group and the non-vasospasm group on the 3rd day in the mean middle cerebral artery velocities on TCD. Conclusion : Patients with high levels of CRP on the 1st postoperative day and high velocity of mean TCD on the 3rd postoperative day may require closer observation to monitor for the development of vasospasm.

• Journal of Korean Neurosurgical Society
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• 제59권5호
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• pp.471-477
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• 2016

Objectives : The correction of clinical and radiologic abnormalities in patients with symptomatic ossification of the posterior longitudinal ligament (OPLL) is the current mainstay of treatment. This study aimed to identify radiographic predictors of severity of myelopathy in patients with symptomatic OPLL. Methods : Fifty patients with symptomatic cervical OPLL were enrolled. Based on Japanese Orthopedic Association (JOA) scores, patients were divided into either the mild myelopathy (n=31) or severe myelopathy (n=19) group. All subjects underwent preoperative plain cervical roentgenogram, computed tomography (CT), and MR imaging (MRI). Radiological parameters (C2-7 sagittal vertical axis, SVA; C2-7 Cobb angle; C2-7 range of motion, ROM; OPLL occupying ratio; and compression angle) were compared. Compression angle of OPLL was defined as the angle between the cranial and caudal surfaces of OPLL at the maximum level of cord compression Results : The occupying ratio of the spinal canal, C2-7 Cobb angle, C2-7 SVA, types of OPLL, and C2-7 ROM of the cervical spine were not statistically different between the two groups. However, the OPLL compression angle was significantly greater (p=0.003) in the severe myelopathy group than in the mild myelopathy group and was inversely correlated with JOA score (r=-0.533, p<0.01). Furthermore, multivariate regression analysis demonstrated that the compression angle (B=-0.069, p<0.001) was significantly associated with JOA scores (R=0.647, p<0.005). Conclusion : Higher compression angles of OPLL have deleterious effects on the spinal cord and decrease preoperative JOA scores.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.432-434
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• 2006

The additional matters appear to be considered in several aspects for building up power-quality measuring system of transmission system(high voltage system) compared to distribution system(middle or low voltage system). Like in distribution system, input signals are also received from PT and CT source of voltage and current respectively in transmission system and applied in accordance with a certain rate. In this case, very big error rate can be occurred according to the specification of the measuring system as the applying rate is bigger than in distribution system beyond comparison. In addition, when the abnormal signal occurred such as sag/swell, interruption, transient etc., power quality of other sires linked to the system also should be checked to find the accurate cause of the abnormal power-quality signals from the corresponding. site. Accordingly, the accurate diagnosis on the condition of power quality for the system depends on the way how the synchronization system is brought along for each site. This paper will suggest the solution for the most effective system building focused on how to solve the problem of the error rate and synchronization described in the above when building up the measuring system of power quality for transmission system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.545-549
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• 2001

We have produced electrolyte solution out of 1.15M $LiPF_6$ EC/EMC/DEC/PC(30/55/10/5 by vol%) as a reference, and at the same time, performed basic physical property test using a single solvent of 1.15M $LiPF_6$ DEC, DMC, EMC and a 2 component electrolyte solution of 1.15M $LiPF_6$ EC/DEC(1/2 by vol%) and PC/DEC(1/2 by vol%). Cyclic Voltammetry Analysis showed that, compared to existing carbonate organic solvent, the addition of DEC,DMC and EMC brought the de-decomposition peak of salt anion of $PF_6$ and the solvent at lower oxidization potential of 2.3V, 0.7V and 2.1V(vs. $Li/Li^+$). In addition, a kinetics current peak, in which intercalation of Lt is proceeded at 750mV, 450mV(vs. $Li/Li^+$), was confirmed. These findings suggest that the DEC solvent decomposition occurred at an electric potential lower than that of oxidization of existing carbonate organic solvent. Through the impedance analysis, we checked electric charge transfer resistance($R_{ct}$) according to the electric potential of $Li^+$ intercalation at 750mV(vs. $Li/Li^+$), which was the same as the resistance ($R_f$) and cyclic voltammetry of SEI film that was formed at Reference. By doing so, we found that the significant decrease of polarization resistance($R_p$) when Reference was played a part in the formation of compact SEI layer at the initial decomposition reaction.

• 전기화학회지
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• 제2권4호
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• pp.195-201
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• 1999

탈기된 0.1 M $Na_2SO_4$ 수용액에서 Fe-Cr강의 재부동태 특성을 Cr함량, 인가전위 그리고 염소이온의 농도를 변화시키면서 관찰하였다. 염소이온이 없는 경우 재부동태 속도를 나타내는 식 log i=k-n log t에서 -n값은 Cr함량에 관계없이 -1에 수렴하였으나 Cr함량이 증가할수록 재부동태 전류밀도는 낮아졌다. A. C. impedance spectroscopy측정 결과, Cr 함량과 인가전위가 증가할수록 형성된 재부동태 피막의 charge transfer resistance$(R_{ct})$ 값은 상승하였다. 또한 재부동태 동안 흐르는 전류밀도를 Faraday식을 이용하여 피막의 두께를 계산해보면 Cr함량이 증가할수록 얇은 부동태 피막이 형성된다는 것을 알 수 있었다. 그러나 염소이온이 존재하는 경우, 염소이온이 Fe-Cr강의 재부동태를 방해하는 효과는 인가전위가 증가할수록 상승하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.545-549
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• 2001

We have produced electrolyte solution out of 1.15M LiPF$\sub$6/ EC/EMC/DEC/PC(30/55/10/5 by vol%) as a reference, and at the same time, performed basic physical property test using a single solvent of 1.15M LiPF$\sub$6/DEC, DMC, EMC and a 2 component electrolyte solution of 1.15M LiPF$\sub$6/ EC/DEC(1/2 by vo%%) and PC/DEC(1/2 by vol%). Cyclic Voltammetry Analysis showed that, compared to existing carbonate organic solvent, the addition of DEC, DMC and EMC brought the de-decomposition peak of salt anion of PF$\sub$6/$\^$-/ and the solvent at lower oxidization potential of 2.3V, 0.7V and 2.1V(vs. Li/Li$\^$+/\`). In addition, a kinetics current peak, in which intercalation of Li$\^$+/ is proceeded at 750mv, 450mv(vs. Li/Li$\^$+/), was confirmed. These findings suggest that the DEC solvent decomposition occurred at an electric potential lower than that of oxidization of existing carbonate organic solvent. Through the impedance analysis, we checked electric charge transfer resistance(R$\sub$ct/) according to the electric potential of Li$\^$+/ intercalation at 750mv(vs. Li/Li$\^$+/), which was the same as the resistance (R$\sub$f/) and cyclic voltammetry of SEI film that was formed at Reference. By doing so, we found that the significant decrease of polarization resistance(R$\sub$p/) when Reference was played a part in the formation of compact SEI layer at the initial decomposition reaction.

• 임상이비인후과
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• 제29권2호
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• pp.182-189
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• 2018

Background and Objectives : There were few literatures about the relationship between upper airway disorders and cardiovascular risk factors such as hypertension, although an association between impaired lower respiratory function and cardiovascular alterations was often reported. Our purpose was to assess the relationships between chronic sinusitis and hypertension. Materials and Methods : Three hundred subjects with bilateral chronic sinusitis who underwent functional endoscopic sinus surgery between 2015and 2017 were evaluated. Six hundred forty subjects without any nasal diseases were enrolled as a control group. Blood pressure and body mass index (BMI) were measured using a standardized method, and subjects were asked about current use of any antihypertensive medication, history of diabetes, smoking and alcohol drinking habits.Sinusitis group was assessed by nasal endoscopic examination, paranasal sinus CT scan and allergy test. Results : Average systolic and diastolic blood pressures were statistically significantly higher in subjects with sinusitis than control group. Chronic rhinosinusitis was associated with a 1.415-fold (95% confidence interval 1.053-1.930) increased hazard of hypertension after multivariate adjustment. Conclusions : These results suggest that sinusitis is associated with high blood pressure. Therefore patients with sinusitis may need special attention for blood pressure control. Further studies need to be performed to elucidate the pathogenesis behind such associations.