• 정보처리학회논문지B
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• 제19B권3호
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• pp.201-208
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• 2012

혈관 내 초음파 영상(IVUS: Intravascular ultrasoundimages)에서 내강(Lumen) 경계 영역을 검출하는 것은 환자의 심혈관 상태를 파악하는데 중요한 정보를 제공하며, 이를 통해 심혈관계 질환을 예측하고 진단할 수 있다. 따라서 정확하게 내강 경계를 분할하는 것은 매우 중요한 단계이다. 본 논문에서는 비모수적 확률 밀도 함수와 스무딩 함수를 사용하여 자동으로 내강 영역을 분할하는 기법을 제안한다. 각각의 혈관내 초음파 영상들을 극좌표 이미지로 변환 후 웨이블릿 변환을 적용하여 초기 관심 점들을 검출한다. 초기 관심점들 중에서 잡음과 칼슘에 의해 발생된 튀는 점들을 제거하기 위해 비모수적 밀도 함수와 스무딩 함수를 이용하여 튀는 점들을 제거하고 경계면에 해당하는 중요 관심 점만을 남긴다. 마지막으로, 다항곡선 접합(Polynomial curve fitting) 함수를 정의하고 다항식과 실제 내강 경계선에 접합된 관심 점을 이용하여 자연스러운 내강 경계면을 추정한다. 본 논문에서 제안한 방법을 다양한 초음파 영상에 대해 실험한 결과, 기존에 제안된 방법 보다 정확하게 경계면을 검출함을 알 수 있었다.

• 말소리와 음성과학
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• 제9권3호
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• pp.17-23
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• 2017

The present study investigates the effect of Accentual Phrase on F0 using a subset of large-scale corpus of Seoul Korean. Four syllable words which were neither preceded nor followed by silent pauses were presumed to be canonical exemplars of Accentual Phrases in Korean. These four syllable words were extracted from female speakers' speech samples. Growth curve analyses, combination of regression and polynomial curve fitting, were applied to the four syllable words. Four syllable words were divided into four groups depending on the categorical status of the initial segment: voiceless obstruents, voiced obstruents, sonorants, and vowels. Results of growth curve analyses indicate that initial segment types have an effect on the F0 (in semitone) in the nucleus of the initial syllable, and the cubic polynomial term revealed that some of the medial low tones in the 4 syllable words may be guided by the principle of contrast maximization, while others may be governed by the principle of ease of articulation.

• 한국지진공학회논문집
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• 제10권4호
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• pp.25-33
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• 2006

지진해일 위험재해도의 작성과 재해경감대책 수립을 위해서는 연안역의 상세한 수심 및 지형을 이용한 시뮬레이션이 요구되고 있다. 본 연구에서는 Beowulf 병렬계산을 통해 동해 전 영역에서 정밀산정이 가능한 병렬유한요소모형을 이용하여 1993년 7월 12일 동해안에 내습한 지진해일에 대한 시뮬레이션을 수행하고, 그 계산 결과와 관측치와의 비교결과를 제시한다. 또한, 해안에서의 지진 해일고의 통계적 분포에 대해 논하며, 해안에서의 지진해일고의 파고분포가 전반적으로 대수정규분포를 따르는 경향을 제시하였다.

• 천문학회지
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• 제25권1호
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• pp.11-21
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• 1992

Applying mass model to disk galaxy NGC 300, since the observed rotation curve of NGC 300 is flatter than Toomre's mass model n = 1, two cases are used; obtaining parameters $a^n$ and $b^n$ from the polynomial fitting of the observed rotation curve (case A) and from the least square fitting between the observed rotation curve and model rotation curve (case B). In any case, n bas a fixed value of 1. Brandt's mass model is also discussed. which has a shape parameter n = 1.4. Calculated total mass and total mass to luminosity ratio are $3.3{\times}10^{10}M_{\odot}$, l2.1 for case A and $2.8{\times}10^{10}M_{\odot}$, 10.3 for case B. In case of Brandt's model, the values are $4.2{\times}10^{10}M_{\odot}$ and 15.4. The rise in the local mass to luminosity ratio in the outer part of NGC 300 implies existence of massive halo. Other dynamical properties are also discussed.

• Current Optics and Photonics
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• 제4권5호
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• pp.411-420
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• 2020

Non-contact three-dimensional (3D) measuring technology is used to identify defects in miniature products, such as optics, polymers, and semiconductors. Hence, this technology has garnered significant attention in computer vision research. In this paper, we focus on shape from focus (SFF), which is an optical passive method for 3D shape recovery. In existing SFF techniques using interpolation, all datasets of the focus volume are approximated using one model. However, these methods cannot demonstrate how a predefined model fits all image points of an object. Moreover, it is not reasonable to explain various shapes of datasets using one model. Furthermore, if noise is present in the dataset, an error will be generated. Therefore, we propose an algorithm based on polynomial regression analysis to address these disadvantages. Our experimental results indicate that the proposed method is more accurate than existing methods.

• 대한치과교정학회지
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• 제31권3호
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• pp.347-355
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• 2001

상하악 전치부 치열은 치아의 형태 변위, 선천결손 등에 의해 종종 교합관계나 심미성에 문제점을 나타내게 된다. 이러한 문제점을 극복하기 위해 임상의는 전치부 비율을 진단시 이용하게 되나, 치열궁 형태, 견치간 폭경(intercanine width), 치열궁 장경(segment depth)과 치열궁 둘레(arch perimeter)에 따른 전치부 비율의 변화로 인해 이러한 비율을 전치부 교합관계 예측에 직접 적용하는데는 한계가 있다. 이에 본 연구에서는 한국성인 정상교합자 모델(남자:20쌍, 여자:20쌍)에서 상하악 전치부 치열궁 형태를 least square method로 조사하였다. 한국인 정상교합자의 상하악 전치부 치열궁 형태는 다항 함수(polynomial function), 베타 함수(beta function), 하이퍼볼릭 코사인 함수(hyperbolic cosine function) 순으로 곡선 접합(curve fitting)하였으며, 이러한 곡선 접합도는 남녀, 상하악에 관계없이 일정하였다. 또한 곡선접합(curve fitting)된 치열궁 형태를 바탕으로 견치간 폭경(intercanine width), 치열궁 장경(segment depth)과 치열궁 둘레(arch perimeter)간의 상관관계를 구하였다. 이러한 상관관계는 견치간 폭경에 따른 치열궁 형태 예측과 보다 정확한 전치부 비율에 대한 정보를 제공할 것이다.

• 설비공학논문집
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• 제10권6호
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• pp.795-802
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• 1998

For measuring the thermal diffusivity by laser flash method, raw data have to be calibrated using temperature data. We have developed in-process calibration method and polynomial calibration in which thermal diffusivity can be calibrated during measuring, This method is different from existing temperature pre-process calibration method and exponential calibration having various source of error. Using this new calibration method, measurement accuracy was improved about 1∼2% compare to the value by the existing method. We also studied more accurate fitting curve as in Figure 4 was shown the result of measuring output characteristics of IR radiometer with temperature. As illustrated in data, in-process calibration method and polynomial calibration equation is proper than pre-process calibration method and exponential calibration.

• Journal of Pharmaceutical Investigation
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• 제25권1호
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• pp.1-7
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• 1995

After oral administration of various drinking solutions, the initial absorption rate of water through gastrointestinal tract of the rabbits was evaluated using tritinated water $(^3H_2O)$ as a marker to develop the sports drinking beverage for Korean people. The polynomial curve fitting over 20 min was performed using computer program to obtain the initial absorption rate of water from the tangent line of the fitted equation because initial absorption rate of water was more critical compared to elimination rate during exercise. The amount of water absorbed was increased but a large variation was observed among testing preparations in a small study group $(2{\leq}n{\leq}6)$. The initial absorption rate of water from isotonic sports drinking beverages was statistically significant when compared to hypertonic cola but was not significant when compared to hypotonic solutions (potable water and barley water). In case of hypertonic sports dringking beverages (i.e. Takeda), initial absorption rate of water was not improved and efficient when compared to other isotonic sports dringking beverages. The initial absorption rate of water from prescribed isotonic sample solution containing electrolytes, carbohydrates, and vitamins was not statistically significant when compared to other isotonic drinking beverages but showed similar absorption profile. It was obvious that isotonic solutions simultaneously containing electrolytes, vitamins and carbohydrates (sugar and glucose) had a tendency to increase the initial absorption of water compared to hypotonic (potable water and barley water) and hypertonic preparations (orange juice and cola). Although statistical significance of initial absorption rate of water between isotonic sports drinking beverages and hypotonic potable and barley water was not observed, unlike the hypertonic solutions, isotonic sports drinking beverages may aid not only to replenish loss of water, electrolytes and other nutrients during the exercise but also to prevent dehydration and muscle fatigue, resulting in improved physical performance in an exhausted condition.

• 대한공간정보학회지
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• 제19권2호
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• pp.63-73
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• 2011

DGPS(Differential Global Positioning System) 측위에 보정정보로 사용되는 의사거리 보정치(PRC, Pseudo Range Correction)에는 불규칙적으로 이상점, 노이즈, 이상현상이 발생한다. 이러한 의사거리 보정치를 보정정보로 사용한 DGPS 측위의 경우 측위 오차는 증가하게 된다. 따라서 이 연구에서는 발생되는 의사거리 보정치의 이상점, 노이즈, 이상현상을 다항식 곡선 접합을 적용한 모델링을 통해 검출 및 보정하는 기법을 제안하였다. 또한 의사거리 보정치 모델의 검증을 위해 보정 전 후의 의사거리 보정치를 DGPS 측위에 사용하여 측위오차를 분석하였다. 분석 결과, 이상점, 노이즈, 이상현상이 발생하는 의사거리 보정치를 사용한 측위의 RMS 오차는 수평방향으로 3.84m로 나타났고, 보정된 의사거리 보정치를 사용한 측위에서는 RMS 오차가 수평방향으로 1.49m로 나타나서 측위 정확도가 향상되는 것을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1471-1481
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• 2014

This paper presents the new power dissipation model of individual switching device in a high-level modular multilevel converter (MMC), which can be mostly used in voltage sourced converter (VSC) based high-voltage direct current (HVDC) system and flexible AC transmission system (FACTS). Also, the voltage balancing method based on sorting algorithm is newly proposed to advance the MMC functionalities by effectively adjusting switching variations of the sub-module (SM). The proposed power dissipation model does not fully calculate the average power dissipation for numerous switching devices in an arm module. Instead, it estimates the power dissipation of every switching element based on the inherent operational principle of SM in MMC. In other words, the power dissipation is computed in every single switching event by using the polynomial curve fitting model with minimum computational efforts and high accuracy, which are required to manage the large number of SMs. After estimating the value of power dissipation, the thermal condition of every switching element is considered in the case of external disturbance. Then, the arm modeling for high-level MMC and its control scheme is implemented with the electromagnetic transient simulation program. Finally, the case study for applying to the MMC based HVDC system is carried out to select the appropriate insulated-gate bipolar transistor (IGBT) module in a steady-state, as well as to estimate the proper thermal condition of every switching element in a transient state.