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 : 정재홍(J . H . Jung) (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
Image Quality Control for Linear Transducers with Various Frequencies by Using an ATS-550 Phantom
James J. Jung,최재호,정재홍 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.2
The purpose of this study is to evaluate the image quality for linear transducers on the basis of a quality control (QC) protocol using the ATS-550 phantom (ATS, Laboratories, Bridgeport, CT, USA). To evaluate the image QC, we used two linear transducers L9 and ML6-15 and performed eight examinations, which included qualitative and quantitative analyses by three observers. The qualitative analyses mostly showed no difference between the two transducers at various frequencies. However, in the functional resolution, the distinguishing ability of anechoic holes ranged between 13 and 15 MHz in the ML6-15 transducer. For quantitative analyses, the vertical and the horizontal measurements were in the range of 2.00 - 2.02 cm, and the focus rate (%) in the focal zone was greater than 75% (range: L9, 85.22 - 89.78%; ML6 - 15, 81.72 - 88.21%) in most the transducers. For sensitivity, the L9 transducer values (mean ± SD) for all frequencies were 6.02 ± 0.01 cm and the ML6-15 transducer values (mean ± SD) for frequencies 9, 11, 13, and 15 MHz were 6.03 ± 0.02, 6.01 ± 0.01, 5.03 ± 0.05, and 4.03 ± 0.05 cm, respectively. For the signal-to-noise ratio of the gray scale and dynamic image, the mean values of the L9 transducer for frequencies 5, 5.5, 6, 7, and 9 MHz were 2.50 ± 1.44, 2.64 ± 1.52, 2.47 ± 1.43, 2.13 ± 1.35, and 2.03 ± 1.24, respectively. The mean values of the ML6-15 transducer for frequencies 9, 11, 13, and 15 MHz were 4.02 ± 1.67, 3.56 ± 1.60, 2.18 ± 1.14, and 2.48 ± 1.01, respectively. For the contrast-to-noise ratio of the gray scale and dynamic image, mean values of the L9 transducer and the ML6-15 transducer were in the ranges of 0.82 - 0.98 and 0.97 - 1.05, respectively. The image quality of the linear transducer depends on the frequency whereas the diagnostic values depend on the transducer and the frequency selected. As yet, the QC of linear transducers has no standard protocol. The results of this study can be used to understand the characteristics of linear transducers and perform QC tests. Consequently, periodic QC testing of linear transducers can provide improved image quality and increased diagnostic values.
-
소형항공기 캐빈 도어 구조 변형에 의한 공력하중 변화 해석
이철(C. Lee),최재승(J.S. Choi),정재홍(J.H. Jung),정훈화(H.H. Jeong),김지홍(J.H. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
Structural deformations due to flight load acting on the aircraft cabin door cause the deformation of surface profile and gap & mismatch between door and fuselage. In order to assess if the cabin door is opened in the deformed gap & mismatch conditions, CFD on the external flow of whole aircraft, small scale flow in gap & mismatch region and internal flow of inner cabin has been performed simultaneously. 2-D parametric studies are conducted in parallel for sensitivity analysis of design parameters. The safety of cabin door was confirmed by the analysis and was verified by flight test.
-
세장형 물체 주의 고앙각 유동의 비대칭 와류 및 측력 특성에 관한 수치적 연구
정성기(S.K. Jung),정재홍(J.H. Jung),명노신(R.S. Myong),조태환(T.H. Cho) 한국전산유체공학회 2006 한국전산유체공학회지 Vol.11 No.3
Flow around a guided missile in high maneuver. i.e. at a high angle of attack. shows complex phenomena. It is well known that even in geometrically symmetric conditions the flow around a missile at high angles of attack can generate unexpected large side forces and yaw moments due to asymmetric vortices. In this paper, a CFD code (FLUENT) based on the Navier-Stokes equations was used for the numerical analysis to find a suitable numerical mechanism for generation of asymmetric vortices. It is shown that a numerical technique of applying different surface roughness to a specific area of the missile nose surface gives the best fit in comparison with the experimental results. In addition, a numerical investigation of variations of side forces and pressure distributions with angle of attack and roll angle was conducted for the purpose of identifying the source of vortex asymmetries.
-
KC-100 항공기 주날개의 결빙에 의한 공력 영향성 연구
이창훈(C.H. Lee),신성민(S.M. Sin),정성기(S.K. Jung),명노신(R.S. Myong),조태환(T.H. Cho),정재홍(J.H. Jung),정훈화(H.H. Jeong) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
Ice accretion on aircraft surface in icing condition induces external shape changes that may result in a hazard factor for aircraft safety. In case of aircraft main wing with high lift equipment, ice accretion is observed around leading edge and flap. During the design phase, location of ice accretion and associated aerodynamic characteristics must be investigated. In this study, icing effects on aerodynamic characteristics of the main wing section of KC-100 aircraft are investigated using an Eulerian-based FENSAP-ICE code in various icing conditions.
-
사료급여방법이 제주재래마의 체성장 및 도체품질에 미치는 영향
오운용(W . Y . Oh),강태홍(T . H . Kang),김동철(D . C . Kim),진신흠(S . H . Jin),홍성귀(S . K . Hong),양승주(S . J . Yang),정재홍(J . H . Jung) 한국축산학회 1993 한국축산학회지 Vol.35 No.6
Nine Cheju Native Horses with an average weight of 169.2㎏ were used in a 238-d (34-wk) fattening trial designed to evaluate the effects of feeding method on growth performance and carcass characteristics. Horses were randomly alloted to three treatment groups: T₁ 6-wk (Former fattening period: FFP) + 28-wk (Latter fattening period: LFP), T₂, 9-wk (FFP) + 25-wk (LFP), T₃, 12-wk (FFP) + 22-wk (LFP). During the FFP, concentrate was restricted at approximately l.5% of their body weights but horses were allowed ad libitum access to concentrate during the subsequent LFP. The horses were individually penned in 2.5-m×3-m pipe stalls with front feeding gates. They were allowed 3 h of exercise in a pen (50-m×30-m) outside the barn monthly. Horses were weighed at 30-d intervals and feed consumption was measured daily. At the end of the 238-d fattening period, one horse in each treatment was selected randomly and slaughtered for meat quality evaluation. Results obtained from the present study were summarized as follows; during the overall fattening period, average daily gains (ADG) and nutrient intake (TDN) per ㎏ wt, gain were 0.59, 5.10(T₁), 0.51, 5.84(T₂) and 0.43, 6.37㎏(T₂), respectively. When horses were allowed ad libitum access to concentrate for 28 wk(T₁), ADG and feed efficiency(TDN) were improved by 37%(P$gt;.05) and20%(P$gt;.05)compared to those allowed concentrate free choice for 22 wk(T₃). Horse in T, group had an improved dressing percentage and carcass weight with good quality grades(intramuscular fat, meat color, fat color). Taste panelists(150 amateures) detected no difference from longissimus lumborum steaks between Cheju Native Horse and improved Cheju Native Cattle, but found juiciness and meat flavor were superior to those of beef.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
