http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Joon Chung (검색결과 5,242 건)
- 무료
- 기관 내 무료
- 유료
-
-
-
( Han Wook Chung ),( Yu Jin Ko ),( Sang Wook Lee ),( Hyun Woong Lee ),( Hyung Joon Kim ) 대한간학회 2013 춘·추계 학술대회 (KASL) Vol.2013 No.1
Background/Aims: Quantitative HBsAg (qHBsAg) titers are emerging as useful tools for measuring viral load and predicting predicting virologic response (VR). This study aimed to determine whether serial monitoring of HBsAg levels could predict virologic response to entecavir(ETV) & clevudine(CLV) therapy in treatment-naive patients with CHB Methods: A total of 157 treatment-naive patients with CHB, who visited Chung-Ang University Hospital between January 2007 and December 2008, were enrolled in this study (100 males). 97 patients(69 males, mean age 48) were treated with ETV for average 53 months, and 60 patients (31 males, mean age 43) were treated with CLV for 26months average. HBsAg levels were measured at baseline, week 12, 24, and 48. All patients were assessed for virological response (HBV DNA<140 copies/mL). Serum HBV DNA was quantified using the real time PCR assay (Artus HBV LC PCR Kit, Roche Diagnostics, lower limit of quantification, 140 copies/mL). Results: In 97 ETV-treated patients, the rates of virological response were 56.7% (55/97) at 48months and 60 CLV-treated patients, 30% (18/60) at 24 months, respectively. Mean reduction of baseline HBV DNA was -5.3, and -4.9 log10 copies/mL. In 55 VR patients treated with ETV, 43(78.1%) patients showed early decline of HBsAg titer and 31(56.3%) patients had lower baseline HBsAg levels (< 3.7 log IU/mL). In 18 VR patients treated with CLV, 9(50%) patients showed early decline of HBsAg titer and 11(61.1%) patients had also lower baseline HBsAg levels (< 3.7 log IU/mL) . Conclusions: Early decline of HBsAg was useful for predicting VR, and baseline HBsAg could be indicative as well in CHB patients treated with ETV than patients treated with CLV.
-
김승환,김인병,정순미,정성필,장석준 대한외상학회 1999 大韓外傷學會誌 Vol.12 No.1
$quot;Background: Paragliding injuries are increasing recently due to the growing popularity of this sport. This topic has been discussed in numerous journals in the European countries with large mountains, such as Austria, Germany and Switzerland, Those studies gave information regarding the flight phase during which an injury ocurred, the type and site of injury, and suspected reasons for the accidents. This study was done to compare our data to those of other nations and give preventive advices to reduce injuries occurring during paragliding. Method: Nineteen paragliders documented as having injuries during paragliding at Chung-Ju, Korea from 1990 to 1997 were included in the study. Their accident reports including medical records, were analyzed retrospectively. Result: Eighteen of the injured were male with one female and their mean age was 25.6 years old. Five injuries were suffered during take-off, of which technical error was the cause in most cases. Also, 5 injuries occurred during flight due to a sudden change of thermal and wind condi- tions. The majority of injuries were suffered during the landing period, affecting 9 paragliders. They were mostly due to forced landings, unexpected obstacles, and sudden change of wind conditions. Thirty-three percent suffered spine trauma and 29% were involved in injuries of the lower extremities. Upper limb injuries occurred in 19%, and 19% also suffered cerebral concussion or contusion. Conclusion: We have found that spine and ankle injuries were commonly occur during paragliding, especially the landing phase. Proper knowledge of the procedures, adequate training and appropriate foot wear could help in reducing injuries while paragliding.$quot;
-
鄭準基 弘益大學校 1989 弘大論叢 Vol.21 No.2
. High speed and heavy cutting performed for improving the surface quality and productivity, are often prevented due to chatter phenomena. Chatter is a violent relative vibration between workpiece and tool in machining of metals, and is an important limiting factor of production rate and surface quality, and reduces the tool life and the dynamic performance of machine tool itself. In this study, in order to suppress the chatter, a modified tool-post combined with the spring and damper was designed and used in the actual cutting test. The results of this study are summerized as follows; The spring and damper adopted in the modified tool-post have the suppressing effects of chatter, and there exists an optimum combination between spring constant and damping ratio.
-
-
鄭準基 弘益大學校 1983 弘大論叢 Vol.15 No.2
The chatter analysis has been studied by many authors using non-linear theory. In this study, the stability chart was obtained experimentally in lathe turning, and was compared with the result of chatter analysis by non-linear theory qualitatively. From experimental results, it was verified that the stability of cutting process is affected by the depth of cut in the following manner. Keeping the rotational speed of workpiece constant, as the chip thickness is increased from zero, the stability can be distinguished by three ranges; (a) unconditionally stable range, (b) conditionally stable range, (c) unstable range. In the conditionally stable range the system is stable for small disturbances but unstable when these exceed a certain level. When the chatter occurs, the amplitude initially increases and stabilized itself at a finite level. This phenomenon agree well with the analysis of non-linear theory qualitatively.
-
정준기,조성산,박성호 弘益大學校 科學技術硏究所 1996 科學技術硏究論文集 Vol.7 No.1
On-line monitoring of cutting tool failure such as wear and fracture plays an important role in automation and optimization of machining processes, enhancement of part quality, and cost reduction. Considerable research has been conducted to apply acoustic emission (AE) to detection of tool failure and monitoring of machining processes of its fairly straightforward means of measurement and high sensitivity. In the present study, turning experiments were conducted with two-layer (WC/TiC/Al203) and three-layer (WC/TiC/Al203/TiN) coated tools that exhibit superior wear resistance and high-speed machining capability compared with uncoated tools in order to investigate characteristic variation of AE signals associated with wear of the coated tools and cutting speed. It is observed that the most severe wear of TiN outerlayer of three-layer coated tools occurs on the rake face, and that the wear resistance of the TiN outerlayer and the effect of outerlayer material on the magnitude of initial root mean square of AE decrease with the increase of cutting speed. Although characteristic variation of AE signal with the wear of tools exhibits slight dependence on the cutting speed, it is demonstrated that rapid increase of AE signals at the final stage of tool life can be utilized for on-line monitoring of tool failure in high speed machining.
-
鄭準基 弘益大學校 科學技術硏究所 1992 科學技術硏究論文集 Vol.2 No.-
Acoustic emission sensing is found to be very promising for monitoring plstic deformation, tool wear, tool chipping,qr friction induced chatter. All these factors haveqr a certainqr contribution to theqr final surfaceqr roughness in machinred workpieces. As a result,qr AE should contain the information about what makes the machined surface roughness deviate from theoretical values. Consequently, a properly designed AE sensingqr scheme should be a good candidate for on-line monitoring of surface finish in and may cause the scrapping of the workpiece which waste ther long cutting time andqr substantially reducer the efficiency. If the surface generation mechanisms can be monitored during the rough cutting stage of the start of the finishing stage, any malfunction of the tools or machines can be detected and corrected before the final surface is generated. That will dramatically increase the effectiveness of finishing processes. Therefore, the aim of this study is to evaluate the possibility of using AE technologies to develop an online surface finish monitoring system. In the beginr of this chapter, surface roughness monitoring based of measured acoustic emission in finish turning of steel is evaluated. Several signal processing schemes are applied to the raw AE signals to reveal the information related to the changes of cutting mechanisms and thereby deterioration of surface finish.
-
AE 신호에 의한 선삭과정의 칩형성기구 예측에 관한 연구
鄭準基 弘益大學校 科學技術硏究所 1994 科學技術硏究論文集 Vol.5 No.-
In metal cutting, untended machining is being realized to increase the efficiency of working. As the unmanned automation comes true, the friction and abnormal state of machine tools are being closed up as important matters. The method using AE(Acoustic Emission) has more merits like convenience in handling, sensitivity in signaling, etc, than any other method. Therefore, the application to detecting the wear from machine tools has been tried and the method of detecting the value of AErms Volt has been made use of to study the wear of machine tools. However, in high-speed cutting, occurence of chip breaking as well as wear of tools has become a important problem. Chip rupture is a crucial factor of manufacturing system's stability. In this study, AE signal has been detected and analyzed from chip rupture of turning process. Thus, at the result of experiments to detect the formation of chip by analyzing AE signals, the conclusion like the following are obtained, by way of adjusting the threshold value, it is possible separate and detect signals from continuous AE signals and burst AE signal. The count rate of burst AE signal is directly related with the formation of chip generated. It is possible to detect the chip formation by use of event count rate of burst AE signal.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
