• Journal of Chest Surgery
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• 제25권1호
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• pp.1-16
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• 1992

The quantitatively measured local myocardial perfusion rates with microspheres are used as an objective indicator of even distribution of cardioplegic solution, and the efficacy of the retrograde right atrial route of cardioplegia is evaluated in hearts with various levels of coronary arterial obstruction. After initial antegrade cardioplegia under the median sternotomy and aortic cannulation, 60 hearts from anesthetized New Zealand white rabbits are divided in random order as normal group [ligated left main coronary artery ; MA, MR] and diagonal group [ligated proximal diagonal artery ; LA, LR]. Half of each group [N=10] are perfused with antegrade cardioplegia[A] under the pressure of 100 cmH2O and the other half with retrograde right atrial route[R] under the pressure of 60 cmH2O[St. Thomas cardioplegic solution mixed with measured amount of microspheres]. The myocardium is subdivided into segments as A[atria], RV[right ventricle]. S[septum], LV[normally perfused left ventricular free wall], ROI[ischemic myocardium of left ventricular free wall]. LV and RQI are further divided into N[subendocardium] and P[subepicardium]. The resulting local myocardial perfusion rates and N /P of each group are compared with Wilcoxon rank sum test. The weight of the hearts is 5.94$\pm$0.66g, and there are no statistically significant dif-ferences[p>0.05, ANOVA] between six compared group. The mean flow rate[F: ml /g / min] of MR group is comparable with MA group[p>0.05], but in N and L group, there are significantly depressed F with right atrial route of cardioplegia, which means elevated perfusion resistance with this route. In spite of no significant differences in delivered doses of microsphere[DEL] between compared groups[p>0.05, ANOVA], there are significantly depressed REC and NF in hearts with right atrial cardioplegia which suggests increased requirement of cardioplegic solution with this route. The interventricular septum shows poor perfusion with right atrial route of cardioplegia without obstruction of supplying coronary arteries. But, with obstruction of coronary artery supplying septum as in M group, the flow rate is superior with right atrial route of infusion. The left ventricular free wall perfusion rates of every RQI with R route are superior to that of A route[p<0.05]. But, in LV segments, there are unfavorable effects of right atrial cardioplegia in L group, although the subendocardial perfusion is well maintained in N group. The LV free wall of left main group shows depressed perfusion rates with antegrade route as compared with RQI segments of diagonal group. But, by contraries, there are increased perfusion rates and superior N /P ratio with retrograde right atrial route. It implies more effective perfusion with right atrial route of cardioplegia in more proximal coronary arterial obstruction[i.e., M group as compared with L group]. As a conclusion, all region of ischemia have superior perfusion rates with right atrial car-dioplegia as compared with antegrade route, and especially excellent results can be obtained in hearts with more proximal obstruction of coronary arteries which would otherwise result in more severe ischemic damage. But, the depressed perfusion rates of the segments with normal coronary artery in hearts with coronary arterial obstruction may be a problem of concern with right atrial cardioplegia and needs solution.

• 대한기계학회논문집B
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• 제30권7호
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• pp.656-662
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• 2006

The effects of concave hemispherical surface with inclined angle on the local heat transfer from a turbulent round jet impinging were experimentally investigated using transient liquid crystal method. This method suddenly exposes a preheated wall to an impinging jet and then the video system records the response of liquid crystals for the measurement of the surface temperature. The Reynolds numbers were used 11000, 23000 and 50000, nozzle-to-surface distance ratio from 2 to 10 and the surface angles $\alpha=0^{\circ},\;15^{\circ},\;30^{\circ}\;and\;40^{\circ}$. Correlations of the stagnation point Nusselt number according to Reynolds number, jet-to-surface distance ratio and dimensionless surface angle are investigated. In the stagnation point, in term of $Re^n$, n ranges from 0.43 in case of $2{\leq}L/d\leq6$ to 0.45 in case of $6. The maximum Nusselt number occurs in the direction of upstream. The displacement of the maximum Nusselt number from the stagnation point increases with increasing surface angle or decreasing nozzle-to-surface distance. The maximum displacement is about 0.7 times of the jet nozzle diameter.

• Journal of Astronomy and Space Sciences
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• 제40권3호
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• pp.101-111
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• 2023

We conducted a statistical study of polar mesospheric summer echoes (PMSEs) in relation to magnetic local time (MLT), considering the geomagnetic conditions using the K-index (or K). Additionally, we performed a case study to examine the velocity profile, specifically for high velocities (≥ ~100 m/s) varying with high temporal resolution at high K-index values. This study utilized the PMSE data obtained from the mesosphere-stratosphere-troposphere radar located in Esrange, Sweden (63.7°N, 21°E). The change in K-index in terms of MLT was high (K ≥ 4) from 23 to 04 MLT, estimated for the time PMSE was present. During the near-midnight period (0-4 MLT), both PMSE occurrence and signal-to-noise ratio (SNR) displayed an asymmetric structure with upper curves for K ≥ 3 and lower curves for K < 3. Furthermore, the occurrence of high velocities peaked at 3-4 MLT for K ≥ 3. From case studies focusing on the 0-3 MLT period, we observed persistent eastward-biased high velocities (≥ 200 m/s) prevailing for ~18 min. These high velocities were accompanied with the systematic motion of profiles at 85-88 km, including large shear formation. Importantly, the rapid variations observed in velocity could not be attributed to neutral wind effects. The present findings suggest a strong substorm influence on PMSE, especially in the midnight and early dawn sectors. The large zonal drift observed in PMSE were potentially energized by local electromagnetic fields or the global convection field induced by the electron precipitation during substorms.

• 자원환경지질
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• 제18권2호
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• pp.151-157
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• 1985

Events detected by the KIER microearthquake network operated in the Southern Part of Korea for 265 days in 1982~1984 were reviewed, and some of them were identified to be a dynamite explosion from several construction sites. The purpose of the present work is to determine the crustal structure of the Southern Korea using the time-destance data obtained from such explosion seismic records. The time·distance data can be well explained by a crustal model composed of four horizontal layers of which thickness, p and s-wave velocity ($V_p$ and $V_s$) are characterized as follows. 1st layer (surface) ; 0~2km, $V_p=5.5km/sec$, $V_s=3.3km/sec$ 2nd layer (upper crust) ; 2~15km, $V_p=6.0km/sec$, $V_s=3.5km/sec$ 3rd layer (lower crust) ; 15~29km, $V_p=6.6km/sec$, $V_s=3.7km/sec$ 4th layer (upper mantle) ; 29km~ , $V_p=7.7km/sec$, $V_s=4.3km/sec$ The relatively shallow crust·mantle boundary and low $P_n$ velocity compared with the mean values for stable intraplate region are noteworthy. Supposedely, it is responsible for the high heat flow in the South-eastern Korea or an anomalous subterranean mantle. The mean $V_p/V_s$ ratio calculated from the relation between p-wave arrival and s-p arrival times appears to be 1.735 which is nearly equivalent to the elastic medium of ${\lambda}={\mu}$. However, the ratio tends to be slightly larger with the depth. The ratio is rather high compared with that of the adjacent Japanese Island, and the fact suggests that the underlying crust and upper mantle in this region are more ductile and hence the earthquake occurrences are apt to be interrupted. As an alternative curstal model, a seismic velocity structure in which velocities are successively increased with the depth is also proposed by the inversion of the time·distance data. With the velocity profile, it is possible to calculate a travel time table which is appropriate to determine the earthquake parameters for the local events.

• Journal of information and communication convergence engineering
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• 제4권2호
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• pp.62-66
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• 2006

The objective of this thesis is to measure the limit of the real space where wireless Local Area Network (LAN) is used, and to apply this result as reference to set up a real Wireless LAN environment. The organized circumference was composed of Wireless LAN based on IEEE 802.11b of the American standard, and the examination is carried out on the campus. On the real condition of office environment and open space, the ratio of available distance to a signal at each distance was measured and this result was studied as data to embody wireless LAN on the campus. The measurement under an indoor environment was executed under circumstance having two walls and open space, however, was executed respectively under three circumstances: Where no obstacle, where one wall exists, and where two or more walls exist.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1992년도 한국우주과학회보 제2권1호
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• pp.16-16
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• 1993

The Cosmic Mach number M is the ratio of the bulk flow velocity of the galaxrvelocity field on some scale R to the unall scale velocity dispersion within refcions of scale R. Because M is the ratio of two velocities, it is inn-dimansionat and the Here, independent of the amplitude of the power specHim and of the biasplnmeter in the linear theory. We have measured the Mach rnlmber for two observational samples: a spiral galaxy sample(AHM) of Aaronson and hiscoBlaborators with absolute distances measured by the infrared Ttillr-Fisher relatioa and an elliptical galaxy sample(EGALS) of Faber or 0, with distances determined by the relation. The effective depths distances of galaxies from the Local Group of these samples are 1639 km/s and 2862 e/s, respectivelr. The Machnumbers from these observed peculiar velocity Selds He fund as M=0.95 for AHMand M=0.59 for EGALS. We comPBre these calculated Mach numbers with thosefrom meck surweys drawn fuom three cosnulogical medels: the stand8rd biased nh=0.5 CDM modet an open CDM rrudel with gh=0.2, and a medd with thepower-law power specelm P(k)-k-1 and n=1. The Mach rnlmber test can give robust constraints on these cosmelogical nudels whose power spectra have very different shapes at large scales.

• 융합신호처리학회논문지
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• 제13권3호
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• pp.119-129
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• 2012

의료분야에서 조직의 경화는 진단 또는 질환의 진행상황의 파악에 이용되는 중요한 정보의 한 가지이며, 객관적인 진단을 위해서는 경화의 정량적 계측법이 중요하다. 경화의 지표인 점탄성 정수를 비침습적으로 계측하는 방법으로 MRE(Magnetic Resonance Elastography) 법이 제안되고 있다. MRE 법에서는 전파파(propagating wave)의 국소 파장과 국소 감쇠율로부터 점탄성 정수를 구하는데 MRE 화상은 S/N 비가 낮아지므로, 잡음의 영향을 감소시키기 위하여 다중 위상 MRE 화상을 이용한 방법이 검토되고 있다. 본 연구에서는 다중 위상 MRE 화상에 함수를 적용하여 점탄성 정수를 측정하는 방법을 제안한다. 제안 방법은 다중 위상 MRE 화상에 점탄성파를 적용시키지만, 점탄성 정수의 공간방향으로의 변화율이나 화상에 포함된 잡음에 따라 측정값의 공간분해능을 임의적으로 설정할 수 있다는 장점이 있다. 시뮬레이션 화상을 이용한 실험과 silicone-gel phantom을 이용한 실험에 의하여 제안된 방법의 유효성을 확인하였다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제20권1호
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• pp.29-37
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• 2020

Background: This study evaluated the efficacy of three intraoral topical anesthetics in reducing the injection needle prick pain from local anesthetic among children aged 7-11 years old. Methods: It is a prospective, Interventional, parallel design, single-blind, randomized clinical trial in which subjects (n=90) aged 7-11 years were included in the study based on an inclusion criteria. Subjects were divided into three groups based on computer-generated randomization with an allocation ratio of 1:1:1. Groups A, B, and C received benzocaine 20% jelly (Mucopain gel, ICPA health products Ltd, Ankleshwar, India), cetacaine anesthetic liquid (Cetylite Industries, Inc, Pennsauken, NJ), and EMLA cream (2% AstraZeneca UK Ltd, Luton, UK), respectively, according to manufacturer's instructions, for 1 minute prior to local anesthetic injection. After application of topical anesthetic agent, for all the groups, baseline pre-operative (prior to topical anesthetic administration) and post-operative scores (after local anesthetic administration) of pulse rate was recorded using Pulse oximeter (Gibson, Fingertip Pulse Oximeter, MD300C29, Beijing Choice Electronic). Peri-operative (i.e., during the administration of local anesthesia) scores were recorded using Face, Legs, Activity, Cry, Consolability (FLACC) Scale, Modified Children hospital of Eastern Ontario Pain Scale (CPS) behavior rating scale, and Faces Pain Scale (FPS-R) - Revised (For self-reported pain). Direct self-reported and physiological measures were ascertained using FPS-R - Revised and Pulse oximeter, respectively, whereas CPS and FLACC scales assessed behavioral measures. To test the mean difference between the three groups, a one way ANOVA with post hoc tests was used. For statistical significance, a two-tailed probability value of P < 0.05 was considered as significant. Results: The Cetacaine group had significantly lower pain scores for self-report (P < 0.001), behavioral, and physiological measures (P < 0.001) than the other two groups. However, there was no significant difference between the Benzocaine group and EMLA group during palatal injection prick. Conclusion: Cetacaine can be considered as an effective topical anesthetic agent compared to benzocaine 20% jelly (Mucopain gel) and EMLA cream.

• 한국항행학회논문지
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• 제22권4호
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• pp.336-341
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• 2018

본논문에서는 5세대 이동통신 및 WLAN 대역저지 특성을 갖는 UWB (ultra wideband) 안테나를 설계 및 구현하였다. 제안된 안테나는 두 개의 슬롯을 갖는 평면 방사 패치와 스트립선로 양쪽의 기생소자와 뒷면 접지면으로 구성되어 있다. 위쪽의 n-모양의 슬롯은 5세대 이동통신 대역(3.42~3.70 GHz)을 저지하고, 아래쪽의 n-모양의 슬롯은 WLAN (wireless local area network) 대역(5.15~5.825 GHz)을 저지하는데 기여한다. 그리고 UWB 대역 (3.10~10.60 GHz)에서 저지 대역을 제외한 전대역에서의 전압정재파비(VSWR; voltage standing wave ratio)를 2.0 이하로 만족시키기 위해 기생소자를 사용하였다. 안테나의 설계 및 전산모의실험에는 Ansoft사의 HFSS (high frequency structure simulator)를 사용하였다. 안테나의 전산모의실험결과 UWB 대역에서 3.36~3.71 GHz, 5.13~5.92 GHz 대역을 저지하며, 구현된 안테나의 측정 결과 3.40~3.72 GHz, 5.08~5.88 GHz 대역을 저지함을 보였다. 전산모의실험과 구현된 안테나의 측정 결과, 저지 대역을 제외한 UWB 전 대역에서 VSWR 값이 2.0 이하를 만족하였다.

• 한국전산구조공학회논문집
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• 제18권3호
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• pp.291-302
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• 2005

구조응답에 기여하는 중요성으로 인하여 추계론적 해석에서는 재료탄성계수의 불확실성에 의한 응답변화도에 대한 연구가 주로 진행되어 왔다. 그러나 추계론적 해석이 의미있는 값을 제공하기 위해서는 가능한 많은 인수에 대한 불확실성을 동시에 고려하여야 한다. 본 연구에서는 구조재료의 중요한 두 인수인 탄성계수와 포아송비에 나타나는 불확실성을 고려한 추계론적 해석을 위한 정식화를 평면문제에 대하여 제안하였다. 이를 위하여 이들 두 인수의 함수로 주어지는 구성행렬의 각 요소에 대한 다항식 전개를 채용하였으며, 두 인수의 불확실성에 따라 나타나는 자기 및 상호상관함수는 n-차 모멘트에 대한 일반식을 적용하여 구성하였다. 다항식 전개에 따라 부행렬의 무한합으로 변형된 구성행렬은 계산상의 편의를 위하여 요구되는 정확도 내에서 절삭하여 사용하였다. 제안된 방법의 검증을 위하여 단순 평면구조를 예제로 택하여 해석하었으며, 해석결과는 국부평균법을 채용한 고전적인 몬테카를 해석 결과와 비교하였다.