FEM에 의한 차체구조용 단일모자형 단면부재의 축압궤특성에 관한 연구

차천석,황창숙,백경윤,김기형,양인영 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.1

차체전면부 사이드부재는 점용접에 의해서 이루어진 모자형 단면형상을 갖는 강도부재로써, 차량의 전면충돌에 있어서 중요한 역할을 한다. 전면충돌에 있어서 차량의 전면부에서 충분한 에너지를 흡수한다면, 승차자에게 가해지는 충격에너지를 경감시킬 수 있다. 따라서, 이러한 강도부재는 충분한 강성을 가져야 하지만, 적절한 압궤 또한 이루어져야 한다. 본 연구에서는 단일모자형 단면부재에 대하여 플랜지부 점용접 간격을 변화시켜 준정적(0.017m/sec) 및 충격합궤(7.19m.sec, 1034J)하에서 압궤특성을 해석하고자 유한요소 프로그램인 LS-DYNA3D을 이용하여 준정적 및 충격압궤 시뮬레이션을 행하였다. 시뮬레이션은 압궤실험 결과와 비교함으로서 시뮬레이션의 타당성을 학인하였다. The hat shaped section members of vehicles compose the base frame which plays an important role in a front-end collision. It consists of the hat shaped section members with spot welds. In front-end collision, the impact energy for the passengers will be decreased as the front parts of vehicles has sufficiently absorbed energy. And then, this structures have not to be very stiff but collapse progressively to absorb the kinetic energy as expected. In this study. LS-DYNA3D has been used for analyzing collapse characteristics on hat shaped section members with respect to spot weld pitches under quasi-static(0.017m/sec) and impact load(7.19m/sec. 1034J). By comparing the results from simulation and the experimental results. the utilization fo simulation has been certified.

Avalanche Hot Source Method for Separated Extraction of Parasitic Source and Drain Resistances in Single Metal-Oxide-Semiconductor Field Effect Transistors

Baek, Seok-Cheon,Bae, Hag-Youl,Kim, Dae-Hwan,Kim, Dong-Myong The Institute of Electronics and Information Engin 2012 Journal of semiconductor technology and science Vol.12 No.1

Separate extraction of source ($R_S$) and drain ($R_D$) resistances caused by process, layout variations and long term degradation is very important in modeling and characterization of MOSFETs. In this work, we propose "Avalanche Hot-Source Method (AHSM)" for simple separated extraction of $R_S$ and $R_D$ in a single device. In AHSM, the high field region near the drain works as a new source for abundant carriers governing the current-voltage relationship in the MOSFET at high drain bias. We applied AHSM to n-channel MOSFETs as single-finger type with different channel width/length (W/L) combinations and verified its usefulness in the extraction of $R_S$ and $R_D$. We also confirmed that there is a negligible drift in the threshold voltage ($V_T$) and the subthreshold slope (SSW) even after application of the method to devices under practical conditions.

Avalanche Hot Source Method for Separated Extraction of Parasitic Source and Drain Resistances in Single Metal-Oxide-Semiconductor Field Effect Transistors

Seok Cheon Baek,Hagyoul Bae,Dae Hwan Kim,Dong Myong Kim 대한전자공학회 2012 Journal of semiconductor technology and science Vol.12 No.1

Separate extraction of source (RS) and drain (RD) resistances caused by process, layout variations and long term degradation is very important in modeling and characterization of MOSFETs. In this work, we propose “Avalanche Hot-Source Method (AHSM)” for simple separated extraction of RS and RD in a single device. In AHSM, the high field region near the drain works as a new source for abundant carriers governing the current-voltage relationship in the MOSFET at high drain bias. We applied AHSM to n-channel MOSFETs as single-finger type with different channel width/length (W/L) combinations and verified its usefulness in the extraction of RS and RD. We also confirmed that there is a negligible drift in the threshold voltage (VT) and the subthreshold slope (SSW) even after application of the method to devices under practical conditions.

Association with Body Mass Index and Risk of Hepatocellular Carcinoma According Liver Disorder Status

( Baek Gyu Jun ),( Sang Gyune Kim ),( Young Don Kim ),( Gab Jin Cheon ),( Jeong-ju Yoo ),( Young Seok Kim ),( Soung Won Jeong ),( Jae Young Jang ),( Sae Hwan Lee ),( Hong Soo Kim ),( Sang-wook Yi ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: Body mass index (BMI) is known to be associated with higher risk of hepatocellular carcinoma (HCC) in the general population. However, the association between BMI and risk of HCC in patients with various liver disease is not well understood. Methods: We used data from National Health Insurance Service (NHIS) that provides compulsory health insurance coverage and national health screening for all citizens in the Republic of Korea. Hazard ratios (HRs) were calculated using Cox regression models to examine associations between body mass index (BMI) and risk of HCC. We included 15016551 adults (aged 18-99 years) who underwent health examinations between 2003 and 2006, in the NHIS database. Participants were classified into six groups according to the liver diseases; liver cirrhosis (LC), hepatitis B or C virus infection (HBVHCV), other liver disease (O-LD), unidentified liver disease with alanine aminotransferase (ALT) ≥40 or aspartate aminotransferase (AST) ≥40 (ALT40), no known liver diseases with 20≤ALT<40 or 20≤AST<40 IU/ml (ALT2040), and ALT<20 and AST<20 (ALT20). Results: During mean 13.7 years of follow-up. HCC occurred in 71570 individuals. In total population, BMI had a non-linear association with HCC. In BMI above 25 kg/m², BMI was positively associated with risk of HCC regardless of liver disorder. In the multivariable adjusted analysis, the HR per 5 kg/m² increase in BMI above 25 kg/m² was 1.48 (95% CI 1.44-1.52) in total population, 1.11 (95% CI 1.00-1.23) in LC, 1.12 (95% CI 1.44-1.52) in HBVHCV, 1.32 (95% CI 1.22-1.44) in O-LD, 1.07 (95% CI 1.03-1.12) in ALT40, 1.47 (95% CI 1.38-1.57) in ALT2040, 1.67 (95% CI 1.32-2.09) in ALT20. In the subgroup analysis for the HCC high-risk group, the HR of HCC (95% CI) for a 5 kg/m2 increase in BMI was 1.21 in HBV-LC (1.01-1.46), 1.13 in other LC (1.08-1.19) and 1.15 in HBV without LC (1.04- 1.27), 1.14 in HCV without LC (0.92 -1.40) and 1.05 in HCV-LC (0.64-1.74). Associations between BMI and risk of HCC in HBV (HR; 1.46 vs 1.05), HCV (HR; 1.30 vs 0.92) and LC (HR; 1.28 vs 1.02) patients were stronger in female than in male. Conclusions: Our study showed that BMI was positively associated with risk of HCC regardless of liver disorder in BMI above 25 kg/m². As the severity of liver disease weakened, the association between increased BMI and HCC became stronger. Inpatients with HBV, HCV, and LC, the harmful effects of higher BMI on HCC risk was stronger in women than in men.

Enhanced Chondrogenic Responses of Human Articular Chondrocytes Onto Silk Fibroin/Wool Keratose Scaffolds Treated With Microwave-Induced Argon Plasma

Cheon, Young Woo,Lee, Won Jai,Baek, Hyun Sook,Lee, Young Dae,Park, Jong-Chul,Park, Young Hwan,Ki, Chang Seok,Chung, Kie-Hyung,Rah, Dong Kyun Blackwell Publishing Inc 2010 Artificial Organs Vol.34 No.5

<P>Abstract</P><P>Silk fibroin (SF) is a natural, degradable, fibrous protein that is biocompatible, is easily processed, and possesses unique mechanical properties. Another natural material, wool keratose (WK), is a soluble derivative of wool keratin, containing amino acid sequences that induce cell adhesion. Here, we blended SF and WK to improve the poor electrospinability of WK and increase the adhesiveness of SF. We hypothesized that microwave-induced argon plasma treatment would improve chondrogenic cell growth and cartilage-specific extracellular matrix formation on a three-dimensional SF/WK scaffold. After argon plasma treatment, static water contact angle measurement revealed increased hydrophilicity of the SF/WK scaffold, and scanning electron microscopy showed that treated SF/WK scaffolds had deeper and more cylindrical pores than nontreated scaffolds. Attachment and proliferation of neonatal human knee articular chondrocytes on treated SF/WK scaffolds increased significantly, followed by increased glycosaminoglycan synthesis. Our results suggest that microwave-induced, plasma-treated SF/WK scaffolds have potential in cartilage tissue engineering.</P>

An Experimental Study on the Axial Impact Collapse Characteristics of Spot Welded Section Members

Cheon-Seok Cha,Kyung-Yun Baek,Young-Nam Kim,Jae-Woung Park,In-Young Yang 한국정밀공학회 2003 International Journal of Precision Engineering and Vol.4 No.2

Clinical significance of radiation-induced liver disease after stereotactic body radiation therapy for hepatocellular carcinoma

( Baek Gyu Jun ),( Young Don Kim ),( Gab Jin Cheon ),( Eun Seog Kim ),( Eunjin Jwa ),( Sang Gyune Kim ),( Young Seok Kim ),( Boo Sung Kim ),( Soung Won Jeong ),( Jae Young Jang ),( Sae Hwan Lee ),( Ho 대한내과학회 2018 The Korean Journal of Internal Medicine Vol.33 No.6

Background/Aims: The aim of this study was to investigate parameters that predict radiation-induced liver disease (RILD) following stereotactic body radiotherapy (SBRT) in patients with hepatocellular carcinoma (HCC) and to identify the clinical significance of RILD. Methods: We retrospectively reviewed the medical records of 117 HCC patients who were treated by SBRT from March 2011 to February 2015. RILD was defined as elevated liver transaminases more than five times the upper normal limit or a worsening of Child-Pugh (CP) score by 2 within 3 months after SBRT. All patients were assessed at 1 month and every 3 months after SBRT. Results: Median follow-up was 22.5 months (range, 3 to 56) after SBRT. RILD was developed in 29 of the 117 patients (24.7%). On univariate analysis, significant predictive factors of RILD were pretreatment CP score (p < 0.001) and normal liver volume (p = 0.002). Multivariate analysis showed that CP score was a significant predictor of RILD (p < 0.001). The incidence of RILD increased above a CP score of 6 remarkably. The rate of recovery from RILD decreased significantly above a CP score of 8. Survival analysis showed that CP score was an independent prognostic factor of overall survival (p = 0.001). Conclusions: CP score is a significant factor to predict RILD in patients with chronic liver disease. RILD can be tolerated by patients with a CP score ≤ 7. However, careful monitoring of liver function is needed for patients with a CP score 7 after SBRT.

Hepatitis B Virus Reactivation after Radiotherapy for Hepatocellular Carcinoma and the Efficacy of Antiviral Treatment: Multicenter Study

( Baek Gyu Jun ),( Young Don Kim ),( Gab Jin Cheon ),( Sang Gyune Kim ),( Young Seok Kim ),( Boo Sung Kim ),( Soung Won Jeong ),( Jae Young Jang ),( Sae Hwan Lee ),( Hong Soo Kim ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: There are no convincing data supporting the routine use of preventive therapy against hepatitis B virus (HBV) reactivation in radiotherapy( RT) for hepatocellular carcinoma (HCC). The aim of this study was to investigate incidence, clinical significance and risk factors of HBV reactivation during RT. Methods: Medical records of 121 HBsAg (+) HCC patients with radiotherapy were reviewed from March 2007 to February 2016. Patients were divided into 2 groups, 24 patients did not receive antiviral therapy before RT and 97 patients underwent antiviral therapy before RT. We evaluated the factors related to HBV reactivation in HCC patients. Results: During the follow-up, 11 (9.1%) of 121 patients developed HBV reactivation. Compared with non-antiviral group, antiviral group had significantly lower rates of HBV reactivation (5/97, 5.2% vs 6/24, 25%: p = 0.002). The incidence of HBV induced radiation induced liver toxicity (RILT) (2.1% vs 12.5%: p = 0.021) and HBV related hepatitis (3.1% vs 12.5% p= 0.057) were low in antiviral group. In contrast, there were no difference in incidences of overall RILT (p = 0.157) and hepatitis (p= 0.478). In multivariate analysis, absence of antiviral prophylaxis and combined with transarterial chemoembolizatoin (TACE) were the risk factors for reactivation. Conclusions: HBV reactivation can occur after radiotherapy. Combination treatment with TACE and non-antiviral treatment are the major risk factors for HBV reactivation during RT. Preventive therapy should be recommended for the patients supposed to receive RT.

Association of CTTN polymorphisms with the risk of colorectal cancer

Seok Youn Lee,Dong Baek Kang,Won Cheol Park,Jeong Kyun Lee,Soo Cheon Chae 대한외과학회 2012 Annals of Surgical Treatment and Research(ASRT) Vol.82 No.3

Purpose: Various studies searching for biomarkers to predict tumor metastasis or prognosis in both esophageal squamous cell carcinoma (ESCC) and head and neck squamous cell carcinoma (HNSCC) are currently underway. However, few data have been reported on its association with colorectal cancer (CRC). Single nucleotide polymorphisms (SNPs) are the most common known form of human genetic variation and may contribute to an increased susceptibility to cancer including CRC. The present study aimed to investigate whether the polymorphisms in the CTTN gene are associated with susceptibility to CRC in the Korean population. Methods: A case-control study was performed to examine the relationship between the CTTN g.-9101C>T, g.-8748C>T, and g.72C>T polymorphisms and the risk of CRC. Polymerase chain reaction-restriction fragment length polymorphism analysis of g.-8748C>T, g.-9101C>T and Taqman analysis of g.72C>T were performed on blood samples from 218 patients with CRC and 533 control individuals. The g.-9101C>T, g.-8748C>T, and g.72C>T SNPs in CTTN and their haplotypes were analyzed. Results: The genotype and allele frequencies of g.-9101C>T, g.-8748C>T, and g.72C>T did not differ between the patient group and the control group. Further, the haplotype of CTTN g.-9101C>T, g.-8748C>T, and g.72C>T did not differ between patient group and the control group. However, the genotype and allele frequencies of CTTN g.-9101C>T were significantly increased in the lymph node positive CRC group compared to the control group. Conclusion: The CTTN g.-9101C>T polymorphism may influence lymph node positive CRC.

Long-term Lamivudine plus Adefovir Dipivoxil Therapy Dose Not Get Worse Significant Renal Function Compared to Adefovir Dipivoxil Monotherapy in Patients with Chronic Hepatitis B

( Baek Gyu Jun ),( Hyuk Jin Moon ),( Sae Hwan Lee ),( Hong Soo Kim ),( Sang Gyune Kim ),( Young Seok Kim ),( Boo Sung Kim ),( Soung Won Jeong ),( Jae Young Jang ),( Young Don Kim ),( Gab Jin Cheon ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1

Aims: The aim of this study was to compare the renal dysfunction and hypophosphatemia between adefovir dipivoxil(ADF) plus lamivudine( LMV) therapy and ADF monotherapy in chronic hepatitis B(CHB) patients. Methods: Between March 2005 and February 2014, 56 patients treated with 10mg/day ADF plus 100mg LMV(Group A) and 41 patients treated with 10mg/day ADF(Group B) were reviewed in our institution. We evaluated estimated glomerular filtration rate (eGFR), serum creatinine and serum phosphate level at the start of ADV plus LMV and ADF monotherapy and every 3 months. Results: The median treatment duration was 73.6 and 80.1 months in groups A and B, respectively. Increased creatinine level(>0.3mg/dl) was seven patients in group A and one patient in Group B(12.3% vs. 2.4%, p=0.134). Decreased eGFR(>50%) was three patients in group A and no patient in group B(0% vs. 5.3%, p=0.262). Hypophosphatemia occurred 14(26.8%) patients in Group A and 11(26.8%) patients in Group B(p=0.799). Mean serum creatinine levels increased and mean eGFR decreased from baseline to end of treatment in Group A( Creatinine 0.75 ± 0.19 vs 0.87 ± 0.21mg/dl, p<0.01, eGFR 108±16 vs 94±18 ml/min p<0.01 ). Mean serum creatinine creatinine levels and mean eGFR were not changed from baseline to end of treatment in Group B( Creatinine 0.79 ± 0.16 vs 0.81 ± 0.16mg/dl, p=0.338, eGFR 102±17 vs 100±18 ml/min p=0.410). Conclusions: Both long-term ADF plus LMV therapy and ADF monotherapy dose not deteriorate significant renal function. However, mild decrease in eGFR and increase of serum creatinine occurred in ADF plus LMV therapy compared to ADF monotherapy.