• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1366-1377
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• 2005

Experimental study was carried out in an atmospheric pressure, laboratory-scale dump combustor showing features of combustion instabilities. Flame structure and heat release rates were obtained from OH emission spectroscopy. Qualitative comparisons were made between line-integrated OH chemiluminescence image and Abel-transformed one. Local Rayleigh index distributions were also examined. Mean temperature, normalized standard deviation and temperature fluctuations were measured by coherent anti-Stokes Raman spectroscopy (CARS). To see the periodic behavior of oscillating flames, phase-resolved measurements were performed with respect to the pressure wave in the combustor. Results on system damping and driving characteristics were provided as a function of equivalence ratio. It also could be observed that phase resolved temperatures have been changed in a well-defined manner, while its difference between maximum and minimum reached up to 280K. These results would be expected to play an important role in better understanding of driving mechanisms and thermo-acoustic interactions.

• 융합신호처리학회논문지
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• 제7권4호
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• pp.178-183
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• 2006

As a lot of researches on the speech signal processing are performed due to the recent rapid development of the information-communication technology. the pitch period is used as an important element to various speech signal application fields such as the speech recognition. speaker identification. speech analysis. or speech synthesis. A variety of algorithms for the time and the frequency domains related with such pitch period detection have been suggested. One of the pitch detection algorithms for the time domain. AMDF (average magnitude difference function) uses distance between two valley points as the calculated pitch period. However, it has a problem that the algorithm becomes complex in selecting the valley points for the pitch period detection. Therefore, in this paper we proposed the modified AMDF(M-AMDF) algorithm which recognizes the entire minimum valley points as the pitch period of the speech signal by using the rotation transform of AMDF. In addition, a threshold is set to the beginning portion of speech so that it can be used as the selection criteria for the pitch period. Moreover the proposed algorithm is compared with the conventional ones by means of the simulation, and presents better properties than others.

• Journal of Chest Surgery
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• 제54권5호
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• pp.342-347
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• 2021

Thoracic surgeons need to be aware of several important points regarding intraoperative lymph node dissection during surgery for non-small cell lung cancer with ground-glass opacities. The first point relates to the need for lymph node dissection during sublobar resection. Since even patients undergoing sublobar resection may benefit from lymph node dissection, it should be selectively performed according to adequate indications, which require further study. Second, there seems to be no difference in postoperative morbidity between systematic sampling and systematic dissection, but the survival benefit from systematic dissection remains unclear. The results of randomized controlled trials on this topic are conflicting, and their evidence is jeopardized by a high risk of bias in terms of the study design. Therefore, further randomized controlled trials with a sound design should investigate this issue. Third, more favorable survival outcomes tend to be positively associated with the number of examined lymph nodes. Minimum requirements for the number of examined lymph nodes in non-small cell lung cancer should be defined in the future. Finally, lobe-specific lymph node dissection does not have a negative prognostic impact. It should not be routinely performed, but it can be recommended in selected patients with smaller, less invasive tumors. Results from an ongoing randomized controlled trial on this topic should be awaited.

• 한국산학기술학회논문지
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• 제15권9호
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• pp.5877-5884
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• 2014

최근 기후변화와 기상이변 등으로 동절기에 더욱 가혹한 기상 조건이 자주 보고되고 있다. 그러나, 철도차량의 난방용량은 이렇게 극도로 추운 기후환경에서는 객실을 난방하기에 충분하지 않은 경우가 많으며, 이는 난방에 대한 승객의 민원을 야기하는 주요 원인이 되고 있다. 본 연구에서는 외기 온도와 난방 출력이 객실 온도에 미치는 영향을 알아봄으로써 차량의 난방용량에 따른 운행 가능한 외기온도를 실험적으로 도출하고자 하였다. 실험방법으로는 우선 시험용 철도차량을 대형 기후환경 챔버에 넣고, 다양한 외기온도조건을 모사하였다. 난방 장치 출력의 영향은 난방 장치의 출력을 변화시키면서 객실의 온도를 측정하여 조사하였다. 외기온도가 $-10^{\circ}C$인 조건에서는 난방기의 출력을 최대로 한 경우에도 객실의 평균 온도는 $14.0^{\circ}C$에 불과하여, 동절기의 객실온도 최소 요구조건인 $18^{\circ}C$보다 훨씬 낮았으나, 외기 온도가 $0^{\circ}C$와 $10^{\circ}C$인 경우의 객실온도는 각각 $26.1^{\circ}C$와 $34.0^{\circ}C$였다. 내삽법으로 계산한 결과 객실 내부 온도를 $18^{\circ}C$ 이상으로 유지할 수 있는 최저 외기온도는 $-6.7^{\circ}C$임을 알 수 있었다. 객실 내부에서의 수직 온도 차이는 난방기 출력이 높을수록, 외기온도가 높을수록 커서 10 K 이상 차이가 나는 경우도 있었다. 그러나, 수평 온도 차이는 난방기 출력이나 외기온도에 무관하게 최대 2 K 이하로 매우 낮게 나타났다. 따라서, 우수한 난방성능을 확보하기 위해서는 수직 온도 차이를 줄이는 것이 중요함을 알 수 있었다.

• 대한두개안면성형외과학회지
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• 제17권3호
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• pp.140-145
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• 2016

Background: The nasal septal cartilage is often used as a donor graft in rhinoplasty operations but can vary widely in size across the patient population. As such, preoperative estimation of the cartilaginous area is important for patient counseling as well as operating planning. We aim to estimate septal cartilage area by using facial computed tomography (CT) studies. Methods: The study was performed using facial CT images taken from 200 patients between January 2012 to July 2015. Using the mid-sagittal image, the boundary of cartilaginous septum was delineated from soft tissue using the mean difference in signal intensity (or brightness). The area within this boundary was calculated. The calculated area for septal cartilage was then compared across age groups and sexes. Results: Overall, the mean area of nasal septal cartilage was $8.18cm^2$ with the maximum of $12.42cm^2$ and the minimum of $4.89cm^2$. The cartilage areas were measured to be larger in men than in women (p<0.05). The area decreased with advancing age (p<0.05). Conclusion: Measuring the size of septal cartilage using brightness difference is more precise and reliable than previously reported methods. This method can be utilized as the standard for prevention of postoperative complication.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.846-853
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• 2006

In this study, quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of Concrete-Faced Rockfill Dam(CFRD) was carried out. The purpose of this study is to indicate the most important input parameter and to show the quantitative variation of displacement at the crest of CFR type dam with this input parameter. The rockfill material properties for parametric study were obtained from the results of large scale triaxial tests on 34 rockfill materials in the 22 different sites. From the statistical analysis on these data, some statistical characteristics of rockfill material properties such as property range, distribution characteristics, and correlation between the properties were investigated. based on these characteristics, 27 property combinations were constituted by Latin Hypercube sampling method. Dam crest displacements after construction, impounding, and earthquake loading were evaluated by static and dynamic numerical analysis on each combination. From the sensitivity analysis, it was found that the crest displacement of CFR type dam was absolutely affected by the shear modulus of rockfill material and the effect of friction angle of it was negligible. This relative difference of sensitivity was more outstanding in case of crest settlement than in case of crest horizontal displacement. Also, it was found that the settlement and horizontal displacement of dam crest logarithmically decreased as the shear modulus increased and the difference between the maximum value and the minimum vale amounted to about 9.5 times in case of settlement and about 10 times in case of horizontal displacement.

• 한국컴퓨터정보학회논문지
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• 제16권12호
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• pp.103-112
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• 2011

움직임 예측은 동영상 인코딩 과정에서 가장 많은 연산량을 차지하는 매우 중요한 처리과정이다. H.264/AVC에서는 움직임 예측을 할 때 정수 화소 단위 뿐만 아니라 부화소 단위까지 예측을 실시함으로써 영상의 압축률을 매우 높일 수 있다. 하지만 이로 인해 계산량이 더욱 증가되는 문제점이 있다. 일반적으로 움직임 예측시 각 블록들 간의 절대 변환 오차(SATD : Sum of Absolute Transform Difference)는 최소점을 기준으로 포물선 형태를 가지는 특성이 있다. 본 논문에서는 이러한 특성을 이용하여 움직임 예측 과정에서 필요한 탐색점을 줄이는 방법을 제안하였다. 제안한 방법은 연산 처리 시간을 감소시킴으로써 계산의 복잡도를 줄일 수 있었다. 제안한 기법을 적용한 결과, 기존의 고속 움직임 예측 알고리즘들과 비교하여 화질 저하는 적은데 비해, 인코딩시 움직임 예측 과정에 서 약 20%정도 처리속도를 감소시키는 결과를 얻었다.

• Radiation Oncology Journal
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• 제5권2호
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• pp.157-163
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• 1987

It is known that fixed source to skin distance (SSD) cannot be used when the treatment field is sloped or larger than the size of second collimator in electron beam irradiation and inverse square law using effective ssd should be adopted. Effective SSDs were measured in different field sizes in each 6, 9, 12, 15 and 18MeV electron energy by suing NELAC 1018D linear accelerator of Kosin Medical Center. We found important parmeters of effective SSD. 1. Minimum effective SSD was 58.8cm in small field size of $6\pm6cm$ and maximum effective SSD was 94.9cm in large field size of $25\pm25cm$, with 6MeV energy. It's difference was 36.1cm. The dose rate at measuring point was quite different even with a small difference of SSD in small field $(6\times6cm)$ and low energy (6 MeV). 2. Effective SSD increased with field size in same electron energy. 3. Effective SSDs gradually increased with the electron energies and reached maximum at 12 or 15 MeV electron energy and decreased again at 18MeV electron energy in each identical field size. And so the effective SSD should be measured in each energy and field size for practical radiotherapy.

• Imaging Science in Dentistry
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• 제43권1호
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• pp.1-6
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• 2013

Purpose: This study investigated the possible correlation between the mineralization of the second molars and the chronological age of a sample population of the state of Paraiba, Brazil. Materials and Methods: One thousand eight hundred fifty-four digitized panoramic images using a scanner of a private dental radiology service were obtained in six months. Of these, 457 were selected from patients aged 4.6 to 16 years who met certain criteria. The images were assessed twice by a radiologist with 5 years experience. A minimum interval of 30 days between the evaluations of the same patient was established. To analyze the relationship between chronological age, calcification level proposed by Demirjian et al in 1973, gender, and tooth, a multiple linear regression model was adjusted, taking age as the response variable (p<0.05). Results: The gender and calcification level were significantly correlated with the age of the patients (p<0.05). There was a significant difference between the average age of the patients' upper teeth compared to the lower ones in both genders (p<0.05). The dental development occurred earlier in female individuals than in male ones, and there was no significant difference between the right and left second permanent molars. Conclusion: It was observed that ethnic variables are related to certain parameters of age and sex identification in the Brazilian population, providing important information for forensic evaluations.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.1019-1022
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• 2005

최근 정보 통신 기술의 급속한 발전에 의해 음성 신호 처리에 관련된 많은 연구가 진행됨에 따라 피치 주기는 음성 인식, 화자 식별, 음성 분석 및 합성 등과 같은 많은 응용분야에서 중요한 요소로써 적용되고 있다. 이러한 피치 주기 검출에 관련된 시간 영역과 주파수 영역에서의 많은 알고리즘이 제안되었으며, 시간 영역의 피치 검출 알고리즘의 하나인 AMDF(average magnitude difference function)는 각 valley점의 거리를 피치 주기로 계산한다. 그러나 피치 주기 검출을 위한 valley점 선정에 있어서 알고리즘이 복잡해지는 문제점이 발생한다. 따라서 본 논문에서는 AMDF의 회전변환을 이용하여 전체 최소 valley점을 음성 신호의 피치 주기로 인식하는 간단한 알고리즘을 제안하였으며, 음성의 시작구간에 대해 경계값을 설정하여 피치 주기 선정에 대한 판단기준으로 사용하였다. 그리고 제안한 알고리즘을 시뮬레이션을 통해 기존의 방법들과 비교하였다.