• 대한두경부종양학회지
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• 제24권2호
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• pp.179-183
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• 2008

하모닉 스칼펠은 낮은 온도에서 작용하여 주변 조직에 열손상을 적게 주는 원리로 인해 수술 후 통증, 구강 섭취, 일상 생활로의 복귀에 기존의 전기 소작술에 비해 유의한 이점을 지니며 이를 바탕으로 수술에 대한 환자의 주관적 만족도를 높임을 확인할 수 있었다.

• Investigative Magnetic Resonance Imaging
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• 제22권1호
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• pp.37-49
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• 2018

Purpose: The effect of global inhomogeneity on quantitative susceptibility mapping (QSM) was investigated. A technique referred to as Simultaneous Unwrapping Phase with Error Recovery from inhomogeneity (SUPER) is suggested as a preprocessing to QSM to remove global field inhomogeneity-induced phase by polynomial fitting. Materials and Methods: The effect of global inhomogeneity on QSM was investigated by numerical simulations. Three types of global inhomogeneity were added to the tissue susceptibility phase, and the root mean square error (RMSE) in the susceptibility map was evaluated. In-vivo QSM imaging with volunteers was carried out for 3.0T and 7.0T MRI systems to demonstrate the efficacy of the proposed method. Results: The SUPER technique removed harmonic and non-harmonic global phases. Previously only the harmonic phase was removed by the background phase removal method. The global phase contained a non-harmonic phase due to various experimental and physiological causes, which degraded a susceptibility map. The RMSE in the susceptibility map increased under the influence of global inhomogeneity; while the error was consistent, irrespective of the global inhomogeneity, if the inhomogeneity was corrected by the SUPER technique. In-vivo QSM imaging with volunteers at 3.0T and 7.0T MRI systems showed better definition in small vascular structures and reduced fluctuation and non-uniformity in the frontal lobes, where field inhomogeneity was more severe. Conclusion: Correcting global inhomogeneity using the SUPER technique is an effective way to obtain an accurate susceptibility map on QSM method. Since the susceptibility variations are small quantities in the brain tissue, correction of the inhomogeneity is an essential element for obtaining an accurate QSM.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.141-149
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• 2003

본 논문에서는 초음파 의용 영상시스템의 B-모드 영상으로 잘 관찰되지 않는 암이나 종양을 진단하기 위하여 인체 연조직의 탄성계수를 측정하여 영상화하는 방법을 제안하였다. 연조직의 단단함을 측정하기 위하여 조직에 정현파 진동을 인가하고 연조직의 기계적인 진동의 크기를 초음파 영상의 스페클 밝기의 시간적 변화를 추정하여 구하였다. 제안한 방법은 B-모드 영상에서 비교적 적은 계산량으로 쉽게 조직의 단단함을 추정할 수 있음을 시뮬레이션과 실험으로 검증하였다

• 대한치과의사협회지
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• 제48권9호
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• pp.670-679
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• 2010

Esthetic demands for dental treatment are increasing every day. The interdisciplinary relationship of the restorative treatment, periodontal therapy and other treatments such as endodontics, orthodontics and so on is more emphasized nowadays to reconstruct the hard and soft tissue foundation for the esthetic restorative treatment. This article will focus on the periodontal plastic surgery for esthetic restorative treatment. These followings will be discussed. 1. Understand the relationship between teeth and gingival scaffold for esthetics 2. Discuss the classification and treatment of gummy smile 3. Recognize the gingival margin irregularities by gingival recession and how to achieve the harmonic soft tissue margins 4. describe the hard and soft tissue augmentation for ridge augmentation.

• 대한전자공학회논문지
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• 제27권12호
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• pp.1916-1924
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• 1990

In this paper attenuation effect on the measurement and the tomography of nonlinear parameter is discussed. We perform computer simulation with the method using harmonic components and the method using secondary wave components, and then estimate attenuation effect through the results and compare two measurement techniques. According to simulation result the attenuation effect is more intensive as large n and \ulcorner, and the degree of the attenuation effect is represented as error functions. In the aspect of measuremnet techniques, the method using secondary wave components is more insensitive to attenuation effect than the method using harmonic compnents. We obtain the same result in the nonlinear tomography, and show that the attenuation compensive filter is required because the whole tomogram is affected by frequency dependent attenuation(or nonlinear attenuation)

• 비파괴검사학회지
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• 제36권2호
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• pp.112-120
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• 2016

The nonlinearity parameter is frequently measured as a sensitive indicator in damaged material characterization or tissue harmonic imaging. Several previous studies have employed the plane wave solution, and ignored the effects of beam diffraction when measuring the non-linearity parameter ${\beta}$. This paper presents a multi-Gaussian beam approach to explicitly derive diffraction corrections for fundamental and second harmonics under quasilinear and paraxial approximation. Their effects on the nonlinearity parameter estimation demonstrate complicated dependence of ${\beta}$ on the transmitter-receiver geometries, frequency, and propagation distance. The diffraction effects on the non-linearity parameter estimation are important even in the nearfield region. Experiments are performed to show that improved ${\beta}$ values can be obtained by considering the diffraction effects.

• Clinical Endoscopy
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• 제57권2호
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• pp.164-174
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• 2024

Pancreatic cancers have a poor prognosis, and their incident rates have risen. Endoscopic ultrasonography (EUS) is an efficient and reliable diagnostic modality for pancreatic lesions, providing high spatial resolution. However, while EUS helps to detect minor pancreatic lesions, nearly all solid pancreatic lesions are hypoechoic, which creates difficulty in making differential diagnoses of pancreatic lesions. When diagnosing pancreatic lesions, the performance of image-enhanced EUS techniques is essential, such as EUS elastography or contrast-enhanced harmonic EUS (CH-EUS). CH-EUS diagnosis is based on assessing the vascularity of lesions, whereas tissue elasticity is measured via EUS elastography. Elastography is either strain or shear-wave, depending on the different mechanical properties being evaluated. The usefulness of enhanced EUS techniques is demonstrated in this review for the differential diagnosis of pancreatic lesions, including solid and cystic lesions, and pancreatic cancer staging.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제18권2호
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• pp.77-105
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• 2014

Medical imaging techniques have evolved to expand our ability to visualize new contrast information of electrical, optical, and mechanical properties of tissues in the human body using noninvasive measurement methods. In particular, electrical tissue property imaging techniques have received considerable attention for the last few decades since electrical properties of biological tissues and organs change with their physiological functions and pathological states. We can express the electrical tissue properties as the frequency-dependent admittivity, which can be measured in a macroscopic scale by assessing the relation between the time-harmonic electric field and current density. The main issue is to reconstruct spectroscopic admittivity images from 10 Hz to 1 MHz, for example, with reasonably high spatial and temporal resolutions. It requires a solution of a nonlinear inverse problem involving Maxwell's equations. To solve the inverse problem with practical significance, we need deep knowledge on its mathematical formulation of underlying physical phenomena, implementation of image reconstruction algorithms, and practical limitations associated with the measurement sensitivity, specificity, noise, and data acquisition time. This paper discusses a number of issues in electrical tissue property imaging modalities and their future directions.

• 대한심미치과학회지
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• 제24권1호
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• pp.13-24
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• 2015

임플란트와 주변 연조직에 대한 술식들이 발전함에 따라 임플란트를 통해 저작 기능 뿐 아니라 심미성의 회복도 가능하게 되었다. 최근에는 심미적인 면이 가장 중요한 상악 전치부에도 임플란트를 이용한 수복이 많이 이용되고 있다. 하지만 상악 전치부를 주변 조직과 조화되게끔 임플란트로 재건하는 것은 치과의사에게 여전히 어려운 일이다. 이를 위해서는 경조직의 재건, 연조직의 재건, 그리고 주변 조직과 어울리는 보철물의 제작이 이루어져야 한다. 본 증례에서는 이전의 여러 차례 수술로 인하여 상악 전치부 상실부위의 연조직, 경조직 손실이 심한 상태로 내원한 환자에서 연조직 증강술과 골이식을 시행하고 임시수복물을 통해 심미성을 개선시킨 임플란트 증례가 있어 보고하고자 한다.

• 대한심미치과학회지
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• 제25권1호
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• pp.35-49
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• 2016

최근 심미성에 대한 요구가 점점 증가함에 따라, 이제는 임플란트 수복에 있어서도 기능적인 면 뿐만 아니라 심미적인 면이 더욱 강조되고 있다. 상악 전치부 임플란트 수복은 임상가들에게 항상 도전적인 과제로 다가오는데 그 이유는 다음의 세 가지 요소를 모두 필요로 하기 때문이다. 첫째, 충분한 경조직이 필요하고 둘째, 충분한 연조직이 필요하며 그리고 셋째, 심미적인 수복물이 필요하다. 연조직의 심미성은 그 하부에 있는 경조직에 의존하게 되는데 그 이유는 하부의 경조직의 골격적인 지지가 있어야만 그것을 바탕으로 그 위에 건강하고 심미적인 연조직이 안정적으로 유지될 수 있기 때문이다. 그러므로, 경조직 재건은 심미적인 임플란트 수복에 있어서 첫번째 단계이며, 특히 3차원적으로 적절한 임플란트의 식립 위치 설정은 심미성 있는 최종 수복물을 얻기 위해서 가장 중요한 단계라고 할 수 있다. 그 다음으로 두번째 단계가 순측으로 충분한 두께의 연조직을 얻기 위한 수술 기법이며, 마지막 세번쨰 단계가 적절한 출현외곽을 갖는 임시 수복물을 통해서 얻어진 심미적인 최종 수복물이다. 본 임상 증례 보고는 순측의 골 열개 결손에서의 골 증대술 과정과 전치부 영역에 주로 사용되는 VIP-CT 라고 일컫는 유경 판막술을 이용한 연조직 증대술, 그리고 임시 수복물을 통한 연조직 형태 만들기와 맞춤형 인상 코핑을 이용한 인상채득법 등을 소개함으로써 경조직, 연조직, 수복물의 세 가지 요소가 심미적인 최종 수복물을 위해 서로 어떻게 조화를 이루어내는지 알아보고자 한다.