• 한국정밀공학회지
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• 제28권9호
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• pp.1070-1077
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• 2011

This study intends to assess the defect in the weld zone of titanium grade 2 plate in terms of acoustical anisotropy based on the angle beam method. Depending on the rolling direction, the ratio of wave velocity was found to be 1.08 and the difference in the angle of refraction was more than seven degrees, confirming the presence of acoustical anisotropy. Thus for measuring the length of defect in the weld zone of the titanium plate (thickness of 10mm), the distance amplitude characteristics curves of titanium, TDACC-R and TDACC-T were constructed for the measurements in consideration of the acoustical anisotropy on CRT of the ultrasonic testing equipment. As a result, when the distance amplitude characteristics curve corresponds to the rolling direction, the length of defect was close to the actual measurement within 1mm and when different, the difference was found to be over 4mm. It was affirmed that the acoustical anisotropy should be taken into consideration when measuring the length of defects in the weld zone of the titanium plate with the presence of acoustical anisotropy.

• 한국의학물리학회지:의학물리
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• 제29권1호
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• pp.29-41
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• 2018

The objective of this study was to evaluate the chemical exchange saturation transfer (CEST) effect of amino acids and neurotransmitters, which exist in the human brain, depending on the concentration, pH, and amplitude of the saturation radiofrequency field. Phantoms were developed with asparagine (Asn), ${\gamma}-aminobutyric$ acid (GABA), glutamate (Glu), glycine (Gly), and myoinositol (MI). Each chemical had three different concentrations of 10, 30, and 50 mM and three different pH values of 5.6, 6.2, and 7.4. Full Z-spectrum CEST images for each phantom were acquired with a continuous-wave radiofrequency (RF) saturation pulse with two different $B_1$ amplitudes of $2{\mu}T$ and $4{\mu}T$ using an animal 9.4T MRI system. A voxel-based CEST asymmetry was mapped to evaluate exchangeable protons based on amide (-NH), amine ($-NH_2$), and hydroxyl (-OH) groups for the five target molecules. For all target molecules, the CEST effect was increased with increasing concentration and B1 amplitude; however, the CEST effect with varying pH displayed a different trend depending on the characteristics of the molecule. On CEST asymmetric maps, Glu and MI were well visualized around 3.0 and 0.9 ppm, respectively, and were well separated macroscopically at a pH of 7.4. The exchange rates of Asn, Glu, BABA, and Gly usually decreased with increasing pH. The CEST effect was dependent on the concentration, acidity of the target molecules, and B1 amplitude of the saturation RF pulse. The CEST effect for Asn can be observed in a 9.4T MRI system. The results of this study are based on applying the CEST technique in patients with neurodegenerative diseases when proteins in the brain are increased with disease progression.

• The Korean Journal of Physiology
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• 제19권1호
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• pp.61-72
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• 1985

운동종목별(運動種目別) 선수(選手)들의 심기능(心機能)을 비교(比較)하기 위하며 운동경력(運動經歷)이 3년이상(年以上)이 된 고등학교(高等學校)의 투척(投擲)(7명), 도약(跳躍)(11명), 단거리(短距離)(8명), 장거리(長距離)(14명), 권투(拳鬪)(7명), 배구(排球)(8명) 및 야구(野球)(9명) 선수(選手)와 비선수(非選手)(19명)들의 안정시(安靜時)심전도상(心電圖上)에 나타난 시간간격(時間間隔), 파고(波高) 및 vector를 비교(比較) 분석(分析)하였다. 안정시(安靜時)의 R-R(간격)間隔은 각종목별(各種目別) 선수(選手)들은$0.96{\sim}1.09$ 초(秒)로 비선수군(非選手群)의 0.78초(秒)에 비(比)해 유의(有意)한 서맥(徐脈)을 보여주었다. R-R간격(間隔)은 P-R, Q-T 및 T-P간격(間隔)의 합(合)으르 나타나는데, P-R 및 Q-T간격(間隔)은 각(各 선수군(選手群)과 비선수군간(非選手群間)에 차이(差異)가 없었으나 T-P간격(間隔)은 도약(跳躍), 단거리(短距離), 장거리(長距離) 및 권투선수(拳鬪選手)들에서 비선수군(非選手群)보다 유의(有意)하게 높았다. R-R간격(間隔)은 T-P 및 Q-T간격(間隔)과 유의(有意)한 상관관계(相關關係)가 있었으나 P-R 및 QRS간격(間隔)과는 상관관계(相關關係)가 없었다. 심전도(心電圖)의 파고(波高)를 비교(比較)해 보면 lead $V_5$에서의 P파고(波高)$(Pv_5)$는 비선수군(非選手群)에 비(比)해서 각종목(各種目) 선수군(選手群)이 전반적(全般的)으로 낮은 경향(傾向)을 보여주었고, 특(特)히 투척(投擲) 및 도약선수군(跳躍選手群)은 유의(有意)하게 낮았다. T파고(波高)$(Tv_5)$는 투척선수군(投擲選手群)이 비선수군(非選手群)보다 유의(有意)하게 낮았으나 다른 선수군(選手群)들은 차이(差異)가 없었다. R파고(波高)$(Rv_5)$는 장거리선수군(長距離選手群)을 제외(除外)한 다른 종목선수(種目選手)들과 비선수(非選手)사이에 차이(差異)가 없었다. 장거리선수군(長距離選手群)의 $(Rv_5)$파고(波高)는 비선수(非選手)뿐만 아니라 다른 종목선수군(種目選手群)보다도 유의(有意)하게 높았다. Lead $V_1$에서의 S파고(波高)$(Sv_1)$는 선수군(選手群)과 비선수군(非選手群)사이에 차이(差異)가 없었다. $Rv_5$와 $Sv_1$파고(波高)의 합(合)은 장거리선수군(長距離選手群)만이 다른 종목선수군(種目選手群)들이나 비선수군(非選手群)보다 유의(有意)하게 높았으며 다른 선수군(選手群)들은 비선수군(非選手群)과 차이(差異)가 없었다. 심전도(心電圖)의 vector를 비교(比較)해 보면 P, QRS, T축(軸)의 각도(角度)는 frontal 및 horizontal plane 상(上)에서 각선수군(各選手群)과 비선수군(非選手群)사이에 차이(差異)가 없었다. P vector의 길이는 각선수군(各選手群)이 비선수(非選手)보다 낮은 경향(傾向) 나타냈으며, 특(特)히 horizontal plane에서 투척(投擲), 도약(跳躍), 단거리(短距離) 및 야구선수(野球選手)들이 비선수군(非選手群)보다 유의(有意)하게 낮았다. QRS와 T vector의 길이는 선수군(選手群)과 비선수군간(非選手群間)에 차이(差異)가 없었고, 야구선수(野球選手)만이 frontal plane에서 QRS vector의 길이가 비선수군(非選手群)보다 높았다. 이상(以上)의 결과(結果)를 종합(綜合)해 보면 각종목(各種目) 운동선수군(運動選手群) 전반(全般)은 비선수(非選手)보다 유의(有意)한 서맥(徐脈)을 나타내며 이는 주로 T-P 간격(間隔)이 길기 때문이다. 파고(波高)의 높이와 vector를 비교(比較)해 볼때 각종목(各種目) 운동선수(運動選手)는 전반적(全般的)으로 비선수군(非選手群)보다 P파(波)가 낮았다. 특(特)히 장거리선수군(長距離選手群)은 다른 종목(種目) 선수군(選手群)이나 비선수군(非選手群)보다 $Rv_5$와$Sv_1$파고(波高)의 합(合)이 유의(有意)하게 높았으므로 좌심실(左心室)이 비대(肥大)해 있음을 알 수 있다. 이는 장거리선수(長距離選手)들이 다른 종목선수(種目選手)들에 비(比)해 더 우수(優秀)한 스포츠심장(心臟)임을 시사(示唆)해 주고 있다.

• 한국해안·해양공학회논문집
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• 제33권6호
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• pp.275-286
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• 2021

본 연구에서는 기존에 선형파 이론으로 제시된 반무한방파제 주변의 회절에 대한 해를 중첩하여 직립 이안제 주변에 발생하는 회절에 관한 해석해를 제시하였다. 그리고, 이를 이용하여 이안제 전면과 후면, 그리고 전·후면에 작용하는 합성파력에 대한 해를 유도하였다. 이안제 전면과 후면에서는 회절파와 중복파, 이안제 양쪽에서 회절한 회절파와 회절파 사이의 간섭에 의해 상대진폭이 공간상에서 주기적으로 변하는 양상을 보였다. 규칙파, 일방향 불규칙파 및 다방향 불규칙파를 대상으로 직립 이안제에 작용하는 파력을 검토하였다. 규칙파 내습시 이안제 전·후면의 파력을 모두 고려한 최대 합성파력의 경우 회절을 고려하지 않았을 경우에 비해 최대 1.6배까지 파력이 증가하는 것으로 나타났다. 이는 Jung et al.(2021)이 반무한 방파제에 대해 회절효과를 고려하여 검토한 결과인 1.34배보다 큰 수치이다. 이안제에 작용하는 최대파력은 규칙파, 일방향 불규칙파, 다방향 불규칙파 순으로 크게 계산되었다. 파랑이 비스듬히 입사하는 경우 이안제에 수직으로 입사하는 경우보다 최대파력이 크게 나타나는 경우도 발견되었다. 따라서, 이안제를 설계할 때, 회절효과, 이안제 전·후면에 작용하는 파력, 파랑의 입사각의 고려가 중요함을 알 수 있다.

• The Korean Journal of Physiology and Pharmacology
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• 제22권1호
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• pp.17-21
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• 2018

Our previous studies have confirmed that morroniside has neuroprotective effects. However, the effects of morroniside on cardiac myocardium remain unknown. Rats were anaesthetized with 10% chloral hydrate (0.35~0.4 mL/kg) and an acute myocardial infarction (AMI) was induced by ligating the anterior descending coronary artery (LAD). Following AMI, morroniside was administered intragastrically for 3 consecutive days at doses of 45, 90 and 180 mg/kg, respectively. Lactate dehydrogenase (LDH) and cardiac troponin T (cTnT) activities in AMI rats in the serum were detected with commercial kits. The expression of IL-6, $IL-1{\beta}$ and $TNF-{\alpha}$ in myocardium was detected by Western blotting analysis. We observed a significant decline in the Q(q) wave amplitude in morroniside-treated rats after 72 h. Additionally, treatment of morroniside decreased the levels of LDH and cTnT in AMI rats. We also observed that morroniside reduced the expression of IL-6, $IL-1{\beta}$ and $TNF-{\alpha}$ in myocardium. Taken together, our findings demonstrate that morroniside had effective anti-inflammatory properties in AMI rats.

• 한국해양공학회지
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• 제38권2호
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• pp.43-52
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• 2024

Investigating ship motion under real conditions is vital for evaluating the seakeeping performance, particularly in the design process stage. This study examined the influence of the principal particulars of a trawler on its seakeeping performance. The wave conditions in the Bering Sea are investigated using available data. The length-to-beam (L/B) and beam-to-draft (B/T) ratios of the ship are changed by 10% for the numerical simulation. The response amplitude operator (RAO) motion, root mean square (RMS) value and sensitivity analysis are calculated to evaluate the influence of the trawler dimensions on ship motions. The peak RAO motion affected the ship motions noticeably because of the resonance at the natural frequency. The L/B and B/T ratios are important geometric parameters of a ship that significantly influence its RMS motion, particularly in the case of roll and pitch. The change in the B/T ratio has a good seakeeping performance based on a comparison of the roll and pitch with the seakeeping criteria. The present results provide insights into the seakeeping performance of ships due to the influence of the principal dimensions in the design stage.

• 대한한의진단학회지
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• 제10권1호
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• pp.46-53
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• 2006

Magnetocardiography provides non-invasive three-dimensional electroanatomical imaging of cardiac electrophysiology. The aim of this study is to find the index for using the indicator of magnetocardiography. An object of this study is 214 papers registered on www.pubmed.com. The index used in magnetocardiography is the interval, morphology, amplitude and integrals of QRS complex, P wave, T wave. The current density and electric field map are used, too. A new try of the index is LAS, W-HEAD, Relative Smoothness index(RS index) etc.

• 대한의용생체공학회:의공학회지
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• 제28권5호
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• pp.665-675
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• 2007

The morphological change of ECG is the important diagnostic parameter to finding the malfunction of a heart. Generally ST segment deviation is concerned with myocardial abnormality. The aim of this study is to detect the change of ST in shape using a polynomial approximation method and the reference ST type. The developed algorithm consists of feature point detection, ST level detection and ST shape classification. The detection of QRS complex is accomplished using it's the morphological characteristics such as the steep slope and high amplitude. The developed algorithm detects the ST level change, and then classifies the ST shape type using the polynomial approximation. The algorithm finds the least squares curve for the data between S wave and T wave in ECG. This curve is used for the classification of the ST shapes. ST type is classified by comparing the slopes of the specified points between the reference ST set and the least square curve. Through the result from the developed algorithm, we can know when the ST level change occurs and what the ST shape type is.

• 대한조선학회논문집
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• 제52권3호
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• pp.187-197
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• 2015

This study aims the development of a semi-analytic method for the parametric roll of large containerships advancing in longitudinal waves. A 1.5 Degree-of-Freedom(DOF) model is proposed to account the change of transverse stability induced by wave elevations and vertical motions (heave and pitch). By approximating the nonlinearity of restoring moment at large heel angles, the magnitude of roll amplitude is predicted as well as susceptibility check for parametric roll occurrence. In order to increase the accuracy of the prediction, the relationship between righting arm(GZ) and metacentric height(GM) is examined in the presence of incident waves, and then a new formula is proposed. Based on the linear approximation of the mean and first harmonic component of GM, the equation of parametric roll in irregular wave excitations is introduced, and the computational results of the proposed model are validated by comparing those of weakly nonlinear simulation based on an impulse-response-function method combined with strip theory. The present semi-analytic doesn’ t require heavy computational effort, so that it is very efficient particularly when numerous sea conditions for the analysis of parametric roll should be considered.

• Geomechanics and Engineering
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• 제2권3호
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• pp.177-190
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• 2010

This paper presents the details of indigenous development of the piezovibrocone and calibration chamber. The developed cone has a cylindrical friction sleeve of $150cm^2$ surface area, capped with a $60^{\circ}$ apex angle conical tip of $15cm^2$ cross sectional area. It has a hydraulic shaker, coupled to the cone penetrometer with a linear displacement unit. The hydraulic shaker can produce cyclic load in different types of wave forms (sine, Hover sine, triangular, rectangular and external wave) at a range of frequency 1-10 Hz with maximum amplitude of 10 cm. The piezovibrocone can be driven at the standard rate of 2 cm/sec using a loading unit of 10 ton capacity. The calibration chamber is of size $2m{\times}2m{\times}2m$. The sides of the chamber and the top as well as the bottom portions are rigid. It has a provision to apply confining pressure (to a maximum value of $4kg/cm^2$) through the flexible rubber membrane inlined with the side walls of the calibration chamber. The preliminary static as well as dynamic cone penetration tests have been done sand in the calibration chamber. From the experimental results, an attempt has been made to classify the soil based on friction ratio ($f_R$) and the cone tip resistance ($q_c$).