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고주파 가열 장비를 활용한 터빈로터 휨 교정수식모델 개발
박준수,현중섭,박현구,박광하,Park, Junsu,Hyun, Jungseob,Park, Hyunku,Park, Kwangha 한국전력공사 2021 KEPCO Journal on electric power and energy Vol.7 No.2
The turbine rotor, one of the main facilities in a power plant, it generates electricity while rotating at 3600 RPM. Because it rotates at high speed, it requires careful management because high vibration occurs even if it is deformed by only 0.1mm. However, bending occurs due to various causes during turbine operating. If turbine rotor bending occurs, the power plant must be stopped and repaired. In the past, straightening was carried out using a heating torch and furnace in the field. In case of straightening in this way, it is impossible to proceed systematically, so damage to the turbine rotor may occur and take long period for maintenance. Long maintenance period causes excessive cost, so it is necessary to straighten the rotor by minimizing damage to the rotor in a short period of time. To solve this problem, we developed a turbine rotor straightening equipment using high-frequency induction heating equipment. A straightening was validated for 500MW HIP rotor, and the optimal parameters for straightening were selected. In addition, based on the experimental results, finite element analysis was performed to build a database. Using the database, a straightening amount prediction model available for rotor straightening was developed. Using the developed straightening equipment and straightening prediction model, it is possible to straightening the rotor with minimized damage to the rotor in a short period of time.
이재홍(Jaehong Lee),박광하(Kwangha Park),구재량(Jae Raeyang Koo),박준수(Jun Su Park),박현구(Hyun-Ku Park) 한국기계가공학회 2023 한국기계가공학회지 Vol.22 No.2
A reliability assessment of the repair weld for the steam-turbine bucket cover was performed. The 410 stainless steel alloy was welded via GTAW (gas tungsten arc welding) with an ER410NiMo filler rod. The welding procedure for the steam-turbine bucket cover was qualified using a tensile test, guided-bend test, and hardness measurement. Two-stage post-weld heat treatment was performed to improve the weld metal toughness. The residual stress was then measured using the indentation test method. The mechanical properties of the welded material were assessed via high- and low-cycle fatigue tests and constant load stress corrosion tests in comparison to the performance of the base metal. The repair weld procedure is demonstrated using an original bucket cover. Finally, a high-speed rotational test of a full-size rotor assembled with a welded bucket cover was performed under steam-turbine start-up and shutdown conditions.
SunMi Kim,JaeWoo Jung,InWon Park,ChulMin Ahn,YuIl Kim,KwangHa Yoo,EunMi Chun,JiYe Jung,YoungSik Park,JuHeon Park,JaeYeol Kim,Korean Smoking Cessation Study Group 대한신경정신의학회 2016 PSYCHIATRY INVESTIGATION Vol.13 No.2
Objective-As mental health problems may play an important role in initiating and maintaining cigarette smoking in females and there are an increasing number of female smokers, we evaluated the relationship between smoking status and mental health problems including depression and suicide ideation in women in Korea. Methods-We analyzed the 5-year cumulative data (19 years of age or older, n=32,184) from the Korean National Health and Nutrition Examination Survey (KNHANES) conducted from 2008 to 2012. Logistic regression analyses were used to evaluate associations between cigarette smoking status and mental health parameters while controlling for potentially confounding variables. Results-Among current smokers, females showed higher lifetime prevalence in having a depressive episode, a doctor-diagnosed major depression, a current diagnosis of depression, or receiving treatment for depression in comparison with males. In addition, females were more likely to report on having a depressive episode, suicidal ideation and attempts, and psychiatric counselling within the previous year, as compared to males. Female former smokers showed intermediate characteristics in parameters of mental health status within the previous year, ranking between lifetime non-smokers and the current smokers. Conclusion-Identifying the factors related to mental health status among current smokers can increase opportunities for an early intervention and help reduce the prevalence of smoking and increase smoking cessation rates particularly in females. Developing adaptive coping strategies other than smoking in female youth is potentially important in reducing the initiation of smoking.
Xiao, Rui,Park, Kwangha,Oh, Younshin,Kim, Jinhoi,Park, Chankyu Korean Society for Molecular Biology 2008 Molecules and cells Vol.26 No.4
<P>The genome of replication-competent BERV gamma4 provirus, which is the most abundant ERV family in the bovine genome, was characterized in detail. The BERV gamma4 genome showed that BERV gamma4 harbors 8576 nucleotides and has the typical 5'-long terminal repeat (LTR)-gag-pro-pol-env-LTR-3'retroviral organization with a long leader region positioned before the gag open reading frame. Multiple sequences analysis showed that the nucleotide difference between 5' and 3' LTRs was 4.2% (mean value 0.042) in average, suggesting that the provirus formed at most 13.3 million years ago. Gag separated by a stop codon from pro-pol in the same reading frame, while env resides in another reading frame lacking of a functional surface domain. According to the current bovine genome sequence assembly, the full-length BERV gamma4 provirus sequences were only found in the chromosomes 1, 2, 6, 10, 15, 23, 26, 28, X, and unassigned, although the partial sequences almost evenly distributed in the entire bovine genome. This is the first detailed study describing the genome structure of BERV gamma4, the most abundant ERV family present in bovine genome. Combined with our recent reports on characterization of ERVs in bovine, this study will contribute to illuminate ERVs in the cattle of which no information was previously available.</P>
Identification and Classification of Endogenous Retroviruses in Cattle
Xiao, Rui,Park, Kwangha,Lee, Hoontaek,Kim, Jinhoi,Park, Chankyu American Society for Microbiology 2008 Journal of virology Vol.82 No.1
<B>ABSTRACT</B><P>The aim of this study was to identify the endogenous retrovirus (ERV) sequences in a bovine genome. We subjected bovine genomic DNA to PCR with degenerate or ovine ERV (OERV) family-specific primers that aimed to amplify the retroviral <I>pro/pol</I> region. Sequence analysis of 113 clones obtained by PCR revealed that 69 were of retroviral origin. On the basis of the OERV classification system, these clones from degenerate PCR could be divided into the β3, γ4, and γ9 families. PCR with OERV family-specific primers revealed an additional ERV that was classified into the bovine endogenous retrovirus (BERV) γ7 family. In conclusion, here we report the results of a genome scale study of the BERV. Our study shows that the ERV family expansion in cattle may be somewhat limited, while more diverse family members of ERVs have been reported from other artiodactyls, such as pigs and sheep.</P>
Rui Xiao,Kwangha Park,Younshin Oh,김진회,박찬규 한국분자세포생물학회 2008 Molecules and cells Vol.26 No.4
The genome of replication-competent BERV γ4 provirus, which is the most abundant ERV family in the bovine genome, was characterized in detail. The BERV γ4 genome showed that BERV γ4 harbors 8576 nucleotides and has the typical 5′-long terminal repeat (LTR)-gag-pro-pol-env-LTR-3′ retroviral organization with a long leader region positioned before the gag open reading frame. Multiple sequences analysis showed that the nucleotide difference between 5′ and 3′ LTRs was 4.2% (mean value 0.042) in average, suggesting that the provirus formed at most 13.3 million years ago. Gag separated by a stop codon from pro-pol in the same reading frame, while env resides in another reading frame lacking of a functional surface domain. According to the current bovine genome sequence assembly, the full-length BERV γ4 provirus sequences were only found in the chromosomes 1, 2, 6, 10, 15, 23, 26, 28, X, and unassigned, although the partial sequences almost evenly distributed in the entire bovine genome. This is the first detailed study describing the genome structure of BERV γ4, the most abundant ERV family present in bovine genome. Combined with our recent reports on characterization of ERVs in bovine, this study will contribute to illuminate ERVs in the cattle of which no information was previously available.
( Yewon Kang ),( Kwangha Lee ),( Eun-jung Jo ),( Jung Seop Eom ),( Jeongha Mok ),( Mi-hyun Kim ),( Ki Uk Kim ),( Hye- Kyung Park ),( Min Ki Lee ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-
Background: There are few data regarding effect of early tracheostomy on clinical outcomes in our country. Our study aimed to investigate effect of early tracheostomy on clinical outcomes (including long-term mortality) in patients with prolonged acute mechanical ventilation (PAMV, ventilator care ≥ 96 hrs). Methods: Data were obtained retrospectively from 575 patients, (69.4% male; median age 68 years) who hospitalized at a medical intensive care unit (ICU) of a single university-affiliated tertiary care hospital over 9 years (between March 2008 and February 2017). Early tracheostomy was defined as ≤ 10 days after translaryngeal intubation. Results: Their hospital and one-year cumulative mortality rate after ICU admission were 38.6 % (n=222) and 61.2 % (n=352), respectively. Also, one hundred forty-three patients (24.9%) underwent early tracheostomy, while others classified with late (n=115, 20.0 %) or no tracheostomy group (n=317, 55.1%). When total patients were divided two groups (early versus late or no tracheostomy), there were no significant differences of Acute Physiology and Chronic Health Evaluation II [median 22 interquartile range (16-25) vs 19 (15-25), p=0.172] and Sequential Organ Failure Assessment scores [7 (5-10) vs 6 (4-9), p=0.737] on ICU admission between both groups. However, early tracheostomy group showed higher medical costs during hospital stay [26,609 (17,634-44,066) vs 21,536 (13,974- 36,509) USD, p=0.013], ICU rehabilitation (46.2 vs 20.1%, p<0.001) and lower hospital mortality (21.7 vs 44.2% p<0.001). In stepwise multivariable Cox-proportional hazard model, early tracheostomy [Hazard ratio 1.550 (95% Confidence interval 1.197-2.006), p=0.011] was associated with one-year survival improvement. Conclusions: In our study, early tracheostomy group showed higher total hospital cost during hospital stay. Also, early tracheostomy was associated with higher hospital and one-year survival improvement.