• 대한기계학회논문집A
• /
• 제34권8호
• /
• pp.989-996
• /
• 2010

통계적 회귀모델과 보간모델은 구조공학 분야에서 실제실험과 전산실험의 결과로부터 자료를 분석하고 응답을 예측하기 위해 적용되었으며 최근 10 년 동안 다양한 설계방법론들과 함께 발전해왔다. 그러나 그들은 구조물의 크기와 형상과 같은 공간변수에 대해서만 취급해왔고 시간변수에 따라 변하는 시간-변화 동적응답을 고려할 수 없었다. 본 연구에서는 공간변수와 시간변수를 모두 취급하여 시간-변화 동적응답을 고려할 수 있는 다중응답접근법 기반 통계적 공간-시간 메타모델을 제안한다. 대표적 회귀모델인 반응표면모델과 보간모델인 크리깅모델을 구조공학 예제의 시간-변화 동적응답에 적용한다. 또한 제안한 방법의 성능을 검증하기 위해 실제함수와의 비교를 통해 두 통계적 공간-시간 메타모델의 정확성을 비교한다.

• 정보과학회 논문지
• /
• 제45권3호
• /
• pp.280-287
• /
• 2018

최근 추천시스템과 데이터 분석 분야에서 고차원 형태의 텐서를 이용하는 연구가 증가하고 있다. 이는 고차원의 데이터인 텐서 분석을 통해 더 많은 잠재 요소와 잠재 패턴을 추출가능하기 때문이다. 그러나 고차원 형태인 텐서는 크기가 방대하고 계산이 복잡하기 때문에 텐서 분해를 통해 분석해야한다. 기존 텐서 도구들인 rTensor, pyTensor와 MATLAB은 단일 시스템에서 작동하기 때문에 방대한 양의 데이터를 처리하기 어렵다. 하둡을 이용한 텐서 분해 도구들도 있지만 처리 시간이 오래 걸린다. 따라서 본 논문에서는 인 메모리 기반의 빅데이터 시스템인 아파치 스파크를 기반으로 하는 텐서 분해 도구인 S-PARAFAC을 제안한다. S-PARAFAC은 텐서 분해 방법 중 PARAFAC 분해에 초점을 맞춰 아파치 스파크에 적합하게 변형하여 텐서 분해를 빠르게 분산 처리가능 하도록 하였다. 본 논문에서는 하둡을 기반의 텐서 분해 도구와 S-PARAFAC의 성능을 비교하여 약 4~25배 정도의 좋은 성능을 보였다.

• Archives of Plastic Surgery
• /
• 제41권4호
• /
• pp.366-373
• /
• 2014

Background The advent of skin-sparing mastectomy has allowed for the reconstruction of the breast and nipple with improved cosmesis. However, the nipple-areolar complex (NAC) in Asian patients is more pigmented and scars easily. Therefore, commonly described incisions tend to result in poor aesthetic outcomes in Asian patients with breast cancer. Methods We describe an algorithmic approach to skin-sparing mastectomy incisions in Asian patients on the basis of the location of the biopsy scar and the tumor site and size. Four incision types are described: peri-areolar, a peri-areolar incision with a second distant skin paddle, "racquet handle," and peri-areolar with adjacent skin excision. Results 281 immediate breast reconstructions were performed between May 2001 and February 2012 after skin-sparing mastectomy. The mastectomy incisions used included the peri-areolar design (n=124, 44%), peri-areolar design with a second distant skin paddle (n=39, 14%), "racquet handle" (n=21, 7.5%), and peri-areolar design with adjacent skin excision (n=42, 14%). The traditional elliptical incision and other variants where the NAC outline was not preserved were performed in the remaining 55 patients. The average follow-up was 44.7 months during which there was 1 case of total flap loss and 7 cases of partial flap necrosis; all remaining flaps survived. 24% of the patients (68/281) underwent subsequent nipple reconstruction. Conclusions Our algorithm avoids breast incisions that are randomly placed or excessively long and prevents the unnecessary sacrifice of normal breast skin. This allows skin-sparing mastectomy and immediate breast reconstruction to be performed with a consistently achievable aesthetic result in Asian women without neglecting oncological safety.

• 대한안전경영과학회지
• /
• 제14권2호
• /
• pp.41-48
• /
• 2012

수공구 사용시 과도한 힘은 작업성 근골격계 질환을 일으킬 수 있는 주요 원인중 하나이다. 이와 관련하여, 수공구 파지시 인체 내부에 부과되는 근력과 외적으로 작용된 힘 간의 비율을 이해하는 것이 중요하며, 이는 근육에 부과되는 과도한 힘을 최소화 시키고, 작업에 필요한 힘의 효율성을 극대화 시키는데 필수적이라 할 수 있다. 이러한 비율과 관련하여 많은 연구가 되어 왔으나, 대부분 수리적 인체역학적 모델과 같은 간접적 추정 방법에 의거하고 있는 실정이다. 이러한 인체역학적 모델을 검증하고 개선하기 위하여 해부용 팔 (cadaver)을 활용한 직접적인 근력과 악력 측정이 필수적이다. 본 연구에서는 이러한 해부용 팔을 이용하여 상지 굴근(hand flexor)을 자동으로 제어하고 근력과 함께 악력을 측정할 수 있는 Hand Motion Simulator를 개발하고, 이를 통하여 다양한 사이즈의 손잡이 파지시 요구되는 근력과 외적으로 적용된 악력을 비교함으로써 수공구 손잡이 사이즈에 따른 근력의 효율성에 대하여 측정을 해 보았다. 또한, 적용된 굴근 (FDP & FDS) 간의 힘 비율에 따른 파지법의 차이를 조사해 보았다. 내부에 주어진 근력은 외부로 작용된 악력보다 5.3배 높은 부하가 작용하였으며 이러한 수공구 손잡이 파지시 힘의 효율성 역시 FDP 와 FDS 간의 비율이 3:2 였을 때, 그리고 손잡이 크기가 작을수록 높은 결과를 보였다. 반대로 손잡이의 크기가 커질수록 힘의 효율성은 저하되었다. 또한, 손가락 관절 각도의 경우 FDP와 FDS간의 비율에 따라 상이한 자세를 나타내었다. FDP 굴근의 비율이 높을 경우 손가락 끝마디 관절 (DIP) 의 굴곡을 보였으며, FDS 굴근 비율이 높을 경우 손가락 두 번째 관절(PIP)의 굴곡을 보였다. 본 연구를 통한 결과는 추후 상지작업자에 대한 근골격계 질환 예방 기준안 마련 및 수공구 설계를 위한 기초자료로 활용이 가능할 것으로 보인다.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 Asia Navigation Conference
• /
• pp.203-212
• /
• 2006

The purpose of this research is to suggest the activation plan of Busan port. In the past years, Busan port enjoyed the golden days because of the China's rapid economic growth. But China's continuous development of ports, the trend of increasing container ship size and increasing direct call to China are coming threats to Busan port. So Korea needs to revise the 'Northeast Logistics Hub' strategy because it is considered that Korea ports continuously will handle China's transshipment cargoes. But now China's transshipment cargo share has decreased by direct call to China ports. It means that China has a lot of its local cargoes, so many ship companies change liner service route to handle China cargoes except Bussan ports although Busan port is included in the main trunk route. In the future, Bussan port will not be able to compete again about throughput with China ports if Busan port's transshipment cargo share decreases. So we must find out and develop Busan port's strength which is the competitive edge. By good luck, Busan port has a few opportunities such as the developed feeder network service and geographical advantages. Busan port has many feeder network service like spider's web in any northeast countries so we can suggest that if Japanese shippers use Busan port to distribute their cargoes to Japanese local areas, its transport costs are cheaper than when they use Japan's main ports. In this paper analyzed side of cost when they use Bussan port like hub to distribute their cargo to their local areas. Because most companies tried to reduce the total cost about logistics. Finally, this paper suggests when northeast shippers(China, Japan) use Bussan port which is more economical than their local main ports.

• 한국식품영양학회지
• /
• 제33권6호
• /
• pp.702-709
• /
• 2020

The purpose of this study was to evaluate microbiological contamination of knives and cutting boards in child-care centers. Materials used in this study were swabbed of cutting boards and knives (blade, handle of knife, and joint of handle and blade) in 129 child-care centers. Mean values of total aerobic bacteria of swabs of knives and cutting boards were 1.7±0.7 log cfu/100 ㎠ and 1.7±0.9 log cfu/100 ㎠, respectively. Contamination levels of coliform bacteria from knives and cutting boards were 1.5±0.6 log cfu/100 ㎠ and 1.7±0.8 log cfu/100 ㎠, respectively. Comparing microbiological contamination levels of knives and cutting boards according to type and size of child-care centers, there was no significant difference. Bacillus cereus was detected in knife handles and cutting boards. Diarrhea-type toxin gene (entFM) was detected in B. cereus isolates. Antibiotic resistance tests showed that B. cereus was resistant to β-lactam antibiotics. To reduce microbiological contamination levels of knives and cutting boards in child-care centers and prevent food poisoning from bacteria contamination, continuous education by children's food-service management center is needed for sterilization and disinfection of knives and cutting boards.

• 대한기계학회논문집A
• /
• 제26권5호
• /
• pp.843-850
• /
• 2002

This paper presents a simulation method using the transmission line modeling to reduce simulation runtime of hydraulic control systems. This method is based on separating the system components each other using the transmission line elements prior to simulation, which leads to divide the simulated system into several subsystems suitable for an even more efficient integration. It can also handle nonlinearities and discontinuities without flag signal when restarting integration. By applying variable integration timestep to parallel hydraulic circuits via parallel processing, it is shown that simulation run-time can be reduced significantly compared with that of Runge Kutta method.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1140-1145
• /
• 2003

Image normalization is one of the important areas in pattern recognition. Also, log-polar images are useful in the sense that their image data size is reduced dramatically comparing with conventional images and it is possible to develop faster pattern recognition algorithms. Especially, the log-polar image is very similar with the structure of human eyes. However, there are almost no researches on pattern recognition using the log-polar images while a number of researches on visual tracking have been executed. We propose an image normalization technique of log-polar images using momentums applicable for affine-invariant pattern recognition. We handle basic distortions of an image including translation, rotation, scaling, and skew of a log-polar image. The algorithm is experimented in a PC-based real-time vision system successfully.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.312-315
• /
• 2003

This paper deals with robust control problems of linear systems with matched nonlinear uncertainties. In order to handle the uncertainties, a Lyapunov min-max control approach can usually be adopted. By the way, the min-max control input is required to be switched and provokes chattering phenomena which limit the practical implementation. The magnitude of switching control input which cause chattering is dependent on the size of uncertainties. In this paper, it is shown that the magnitude of the min-max control input can be made small using a well-known disturbance observer technique and only considers the disturbance observing errors. The chattering phenomena can be reduced as small as possible by selecting a high diturbance observer gain. The simulations show that the min-max control with a disturbance observer can reduce chattering phenomena much smaller and guarantee much better robust performance rather than the one without a disturbance observer.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
• /
• pp.177-180
• /
• 2000

Optical burst switching(OBS) is a new switching paradigm to supporting bursty traffic on the Internet efficiently. OBS separates burst level and control level. To handle data burst efficiently, the scheduling schemes in optical burst switching systems must keep track of future resource availability when assigning arriving data bursts to wavelength channels. In this paper, we evaluate the performance of three scheduling schemes which are called Horizon, Single-gap and Multiple-gap, as a basic study for the future research of Optical Internet. Thus, firstly, we analyze the trade-off between the performance and the processing overhead of each scheme. In addition, the performance of OBS system which uses Multiple-gap scheduling is evaluated in detail under various network size. We use simulation for performance evaluation in terms of burst loss rate(BLR), wavelength channel utilization and the number of management data.