• 한국산업융합학회 논문집
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• 제27권1호
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• pp.183-193
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• 2024

Recurrent Neural Network technology that learns past patterns and predicts future patterns using technology for recognizing and classifying objects is being applied to various industries, economies, and languages. And research for practical use is making a lot of progress. However, research on the application of Recurrent Neural Networks for evaluating and predicting the safety of mechanical structures is insufficient. Accurate detection of external load applied to the outside is required to evaluate the safety of mechanical structures. Learning of Recurrent Neural Networks for this requires a large amount of load data. This study applied the Gated Recurrent Unit technique to examine the possibility of load learning and investigated the possibility of applying a stacked Auto Encoder as a way to secure load data. In addition, the usefulness of learning mechanical loads was analyzed with the Gated Recurrent Unit technique, and the basic setting of related functions and parameters was proposed to secure accuracy in the recognition and prediction of loads.

• Journal of Korean Neurosurgical Society
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• 제51권5호
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• pp.247-252
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• 2012

Objective : The anatomical knowledge is the most important and has a direct link with success of operation in cervical spine surgery. The authors measured various cervical parameters in cadaveric dry bones and compared with previous reported results. Methods : We made 255 dry bones age from 19 to 72 years (mean, 42.3 years) that were obtained from 51 subjects in 100 subjects who donated their bodies. All measurements from C3-C7 levels were made using digital vernier calipers, standard goniometer, and self-made fix tool for two different cervical axes (canal and disc setting). We classified into 4 groups (uncinate process, vertebral body, lamina, and pedicle) and measured independently by two neurosurgeons for 28 parameters. Results : We analyzed 23970 measurements by mean value and standard deviations. In comparing with previous literatures, there are some different results. The mean values for uncinate process (UP) width ranged from 5.5 mm at C4 and 5 to 6.3 mm at C3 and C7 in men. Also, in women, the mean values for UP width ranged from 5.5 mm at C5 to 6.3 mm at C7. C7 was widest and C5 was most narrow than other levels. The antero-posterior length of UP tended to increase gradually from C3 to C6. The tip way, tip distance, and base distance of UP also showed increasing pattern from C3 to C7. Conclusion : These measurements can provide the spinal surgeons with a starting point to address bony architectures surrounding targeted soft tissues for safeguard against unintended damages during cervical operation.

• Journal of Advanced Marine Engineering and Technology
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• 제22권3호
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• pp.320-327
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• 1998

The purpose of this study is to design the intelligent speed control system for marine diesel engine by combining the Model Matching Method and the Nominal Model Tracking Method. Recently for the speed control of a diesel engine some methods using the advanced control techniques such as LQ control Fuzzy control or H$\infty$ control etc. have been reported. However most of speed controllers of a marine diesel engine developed are still using the PID control algorithm But the performance of a marine diesel engine depends highly on the parameter setting of the PID controllers. The authors proposed already a new method to tune efficiently the PID parameters by the Model Mathcing Method typically taking a marine diesel engine as a non-oscillatory second-order system. It was confirmed that the previously proposed method is superior to Ziegler & Nichols's method through simulations under the assumption that the parameters of a diesel engine are exactly known. But actually it is very difficult to find out the exact model of the diesel engine. Therefore when the model and the actual diesel engine are unmatched as an alternative to enhance the speed control characteristics this paper proposes a Model Refernce Adaptive Speed Control system of a diesel engine in which PID control system for the model of a diesel engine is adopted as the nominal model and a Fuzzy controller is adopted as the adaptive controller, And in the nominal model parameters of a diesel engine are adjusted using the Model Matching Method. it is confirmed that the proposed method gives better performance than the case of using only Model Matching Method through the analysis of the characteristics of indicial responses.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권3호
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• pp.201-207
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• 2018

Purpose: To develop the reliability growth planning for a subsystem of guided weapon system using PM2-Continuous model. Methods: The target MTBF of the subsystem is set by allocating the system target MTBF to the lower level, where ARINC method is applied. Other model parameters such as initial MTBF, management strategy ratio and average fix effectiveness factor are chosen from historical growth parameter estimates. Given the values of model parameters, the reliability growth planning curve using PM2-Continuous model is constructed and the sensitivity analyses are performed for the changes of model parameters. Results: We have developed the reliability growth plan for a subsystem of guided weapon system using PM2-Continuous model. It was found that the smaller the ratio of initial MTBF to target MTBF, the smaller the management strategy ratio, the smaller the average fix effectiveness factor, and the shorter the development test period, the higher reliability growth is required. Conclusion: The result of this study will be used as a basis for establishing the reliability growth plan, the test period setting and the budget appropriation for the similar system entering the system development stage in the future.

• 한국통신학회논문지
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• 제36권9B호
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• pp.1073-1081
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• 2011

URL 파라미터는 민감한 정보나 제공된 링크에서 임의로 변경하면 보안 위험이 발생하는 것을 포함할 수 있다. 본 논문에서는 전체 URL 파라미터들의 이름과 값을 동시에 암호화하는 Link-E-Param(Link with Encrypted Parameters) 기법을 제안한다. 이 기법은 기존의 일부 URL 파라미터를 감추는 방식과 달리, 공격자에 의한 악의적 URL 파라미터 분석을 근원적으로 불가능하게 함으로써 URL 분석에 기반 하여 웹 사이트로부터 정보를 빼내려는 시도를 막는 역할을 한다. 제안 기법은 서블릿 필터 형태로 구현되기 때문에 서버에 jar파일 설치 후 설정 파일을 작성하기만 하면 기존 프로그램을 수정할 필요 없이 적용이 가능하다. Link-E-Param에서는 다양한 암호화 알고리즘이 지원되도록 구현하였다. 구현된 필터를 적용하여 실험한 결과, 암호화 및 복호화로 인해 사용자가 느끼는 응답 시간의 증가가 수용 가능한 수준이라 볼 수 있는 2~3% 에 불과함을 보인다.

• 한국재료학회지
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• 제25권12호
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• pp.647-654
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• 2015

Self-assembled monolayers(SAM) of microspheres such as silica and polystyrene(PS) beads have found widespread application in photonic crystals, sensors, and lithographic masks or templates. From a practical viewpoint, setting up a high-throughput process to form a SAM over large areas in a controllable manner is a key challenging issue. Various methods have been suggested including drop casting, spin coating, Langmuir Blodgett, and convective self-assembly(CSA) techniques. Among these, the CSA method has recently attracted attention due to its potential scalability to an automated high-throughput process. By controlling various parameters, this process can be precisely tuned to achieve well-ordered arrays of microspheres. In this study, using a restricted meniscus CSA method, we systematically investigate the effect of the processing parameters on the formation of large area self-assembled monolayers of PS beads. A way to provide hydrophilicity, a prerequisite for a CSA, to the surface of a hydrophobic photoresist layer, is presented in order to apply the SAM of the PS beads as a mask for photonic nanojet lithography.

• Journal of Biosystems Engineering
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• 제42권4호
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• pp.283-292
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• 2017

Purpose: Japanese Apricot, a type of plum, has various medicinal and economical applications. Plums are quite popular worldwide, but their deseeding remains a serious impediment to their processing. Therefore, a plum (Japanese Apricot) seed remover (PSR) was developed that can use various types of cutters according to the purpose of the plum processing, and its performance was evaluated. Methods: The proposed PSR, which allows multipurpose cutters, namely, zero-, two-, and four-blade cutters, to be installed, was first designed and manufactured. To identify appropriate parameters related to the cutting pressure, plums were harvested from three regions during three harvesting periods, and their geometrical and mechanical properties were measured. After application of the parameters related to the cutting pressure, a performance test was carried out on both fresh and frozen plums by identifying the ratios of the flesh recovery, seed recovery, seed breakage, deseeding efficiency, and machine efficiency. Results: The results show that, using the proper calculation of the processing parameters, 100% deseeding efficiency was facilitated regardless of the type of cutter used. However, in the case of a four-blade cutter, there are significant differences in the flesh recovery ratio according to the plum setting angle. Between the fresh and frozen plums, all cutters showed a significantly better flesh recovery ratio for the case of fresh plums. Conclusions: This machine will advance the plum processing technology, and eventually help the plum industry flourish.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5963-5973
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• 2011

현재 사용되고 있는 소일네일링 구조물에 관한 설계 및 해석법들은 실내모형실험이나 원형실험 또는 수치해석 결과를 바탕으로 주변지반과 보강네일 사이의 상호작용 메카니즘을 달리 적용함으로서 서로 다른 안전율을 제시하고 있다. 이러한 해석법들은 네일의 강성도나 지반조건 등이 가정된 바와 같이 잘 일치할 경우에는 합리적인 설계법이 될 수 있다. 하지만 이와 조건이 다른 경우 부적절한 결과를 가져올 가능성이 크다. 따라서, 본 연구에서는 원심모형시험기를 사용하여 소일네일링 구조물의 거동과 파괴메카니즘에 관한 매개변수적 실험을 실시하였다. 매개변수적 실험에서는 네일의 길이 및 설치각, 네일과 전면판의 강성도 등을 다양하게 변화시키면서 모형 벽체가 파괴될 때까지 중력수준을 증가시키는 자중실험을 실시하였다. 실험으로부터 얻어진 결과를 바탕으로 매개변수의 변화에 따른 영향, 파괴메카니즘 등을 비교분석하였다. 원심모형실험 결과와 현재 사용되고 있는 방법들과 비교 검토함으로서 기존 방법들에 대한 타당성을 검증하였다.

• 해양환경안전학회지
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• 제25권3호
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• pp.259-268
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• 2019

Even if only two ships are encountered, a collision may occur due to the mistaken judgment of the positional relationship. In other words, if an officer does not know a target ship's intention, there is always a risk of collision. In this paper, the experiments are conducted to investigate how the intention affects the action of collision avoidance in cooperative and non-cooperative situations. In non-cooperative situation, each ship chooses a course that minimizes costs based on the current situation. That is, it always performs a selfish selection. In a cooperative situation, the information is exchanged with a target ship and a course is selected based on this information. Each ship uses the Distributed Stochastic Search Algorithm so that a next-intended course can be selected by a certain probability and determines the course. In the experimental method, four virtual ships are set up to analyze the action of collision avoidance. Then, using the actual AIS data of eight ships in the strait of Dover, I compared and analyzed the action of collision avoidance in cooperative and non-cooperative situations. As a result of the experiment, the ships showed smooth trajectories in the cooperative situation, but the ship in the non-cooperative situation made frequent big changes to avoid a collision. In the case of the experiment using four ships, there was no collision in the cooperative situation regardless of the size of the safety domain, but a collision occurred between the ships when the size of the safety domain increased in cases of non-cooperation. In the case of experiments using eight ships, it was found that there are optimal parameters for collision avoidance. Also, it was possible to grasp the variation of the sailing distance and the costs according to the combination of the parameters, and it was confirmed that the setting of the parameters can have a great influence on collision avoidance among ships.

• Imaging Science in Dentistry
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• 제49권2호
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• pp.139-151
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• 2019

Purpose: This study was performed to investigate the effect of exposure parameters on image quality obtained using a cone-beam computed tomography (CBCT) scanner and the relationship between physical factors and clinical image quality depending on the diagnostic task. Materials and Methods: CBCT images of a SedentexCT IQ phantom and a real skull phantom were obtained under different combinations of tube voltage and tube current (Alphard 3030 CBCT scanner, 78-90 kVp and 2-8 mA). The images obtained using a SedentexCT IQ phantom were analyzed technically, and the physical factors of image noise, contrast resolution, spatial resolution, and metal artifacts were measured. The images obtained using a real skull phantom were evaluated for each diagnostic task by 6 oral and maxillofacial radiologists, and each setting was classified as acceptable or unacceptable based on those evaluations. A statistical analysis of the relationships of exposure parameters and physical factors with observer scores was conducted. Results: For periapical diagnosis and implant planning, the tube current of the acceptable images was significantly higher than that of the unacceptable images. Image noise, the contrast-to-noise ratio (CNR), the line pair chart on the Z axis, and modulation transfer function (MTF) values showed statistically significant differences between the acceptable and unacceptable image groups. The cut-off values obtained using receiver operating characteristic curves for CNR and MTF 10 were useful for determining acceptability. Conclusion: Tube current had a major influence on clinical image quality. CNR and MTF 10 were useful physical factors that showed significantly associations with clinical image quality.