• 대한두경부종양학회지
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• 제10권2호
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• pp.91-101
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• 1994

Nodular thyroid disease is a common clinical problem. The problem in clinical practice is to distinguish malignant or potentially malignant tumor from harmless nodules. The cases of thyroid nodule surgically managed at Department of General Surgery, Soon Chun Hyang Univ. Hospital during the period Jan. 1985 to July. 1992 were reviewed retrospectively. To assess method of distinguishing malignant from benign lesions of the thyroid gland, we reviewed 162 patients with thyroid nodule. There were 61(37.7%) malignant nodules and 101(62.3%) benign nodules. According to the review, distinguishing the benign from the malignant nodule with history, physical examination, clinical manifestation, and duration of illness was not suggested sufficiently. In ultrasonogram of 73 cases, 57.5% of nodules were solid, 20.6% were cystic, 21.9% were mixed solid and cystic. Of these, 28.5% of the operated solid lesions, 12.5% of the mixed lesions, and only 6.7% of the cystic lesions were malignant. Thyroid scanning of 82 cases revealed cold nodules in 60 patients(73.2%), of which 26 cases were malignant(36.6%) 137 patients underwent fine needle aspiration cytology(FNAC), and these results were as follow: sensitiviey was 70.6%, specificity was 93.0%, false-positive rate was 14.3%, and false-negative rate was 15.8%. 41 patients underwent frozen biopsy, and the results as follow: sensitivity was 80.0%, specificity was 89.7%. Neither scintigraphy nor ultrasonogram has sufficient specificity to distinguish benign from malignant nodule. But FNAC and frozen biopsy have sufficient accuracy to differentiate benign from malignant nodule. In the benign nodules, the most common type of operation was total lobectomy (60.4%). Of the malignant nodules, total thyroidectomy with or without modified radical neck dissection was performed in 30 cases(49.2%). We conclude that the single technique used to determine the differential diagnosis of a thyroid nodule are unrealiable. It is therefore essential to combine all avaiable clinical and laboratory information.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.189-199
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• 2016

Many implantable hearing aids are being developed as alternatives to conventional hearing aids which has inconveniences for use and social stigma that make hearing-impaired people avoid to wear it. Particularly, the fully-implantable middle ear hearing devices (F-IMEHD) are being actively studied for mixed or sensorineural hearing impaired people. In development of F-IMEHD, the most difficult problem is improving the performance of implantable microphone. Recently, Cho et al. have studied the tympanic membrane installed microphone which has better sensitivity and is easier to operate on patient than the microphone implanted under the skin. But, it may cause howling problem due to the feedback signal via oval window and ossicle chain from the transducer on round window in the middle ear cavity, therefore, a feedback canceller is necessary. In this paper, we designed NLMS (normalized least mean square) adaptive feedback canceller for F-IMEHD with tympanic membrane installed microphone and a transducer implemented at round window, and computer simulation was performed to verify its operation. The designed adaptive feedback canceller has a delay filter, a 64 point FIR fixed filter and a 8-tap adaptive FIR filter. Computer simulation of the feedback path is modeled by using the data obtained through human cadaver experiment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1972-1986
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• 2017

With the advent of the knowledge economy, science and technology resources have played an important role in economic competition, and their optimal allocation has been regarded as very important across the world. Thus, allocation optimization research for regional science and technology resources is significant for accelerating the reform of regional science and technology systems. Regional science and technology resource allocation optimization is modeled as a double-layer optimization model: the entire system is characterized by top-layer optimization, whereas the subsystems are characterized by bottom-layer optimization. To efficaciously solve this optimization problem, we propose a mixed search method based on the orthogonal genetic algorithm and sensitivity analysis. This novel method adopts the integrated modeling concept with a combination of the knowledge model and heuristic search model, on the basis of the heuristic search model, and simultaneously highlights the effect of the knowledge model. To compare the performance of different methods, five methods and two channels were used to address an application example. Both the optimized results and simulation time of the proposed method outperformed those of the other methods. The application of the proposed method to solve the problem of entire system optimization is feasible, correct, and effective.

• 수산해양기술연구
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• 제31권2호
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• pp.178-189
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• 1995

병렬형 도립진자를 수학적으로 모델링하고 주파수 응답법에 의해 파라미터를 동정하여, $H_\infty$제어이론 중 혼합감도문제에 의거하여 제어계를 설계한 후 응답 시뮬레이션을 한 결과그 응답으로부터 모델링의 불확실성에 대처할 수 있는 강인한 제어계를 구성할 수 있었다. 앞으로 실제 시스템에 대하 s제어들 과제로 남겨두고 있다. 시뮬레이션 응답과는 달리 실제 으답실험에서도 좋은 결과를 얻기 위해서는 여러 가지의 어려움이 있을 것으로 예상된다. 특히 응답 시뮬레이션에서도 나타난 바와 같이 전자가 미소각으로 기울어진 상태에서 제어를 할 경우에도 각 상태의 변동량이 크고, 또한 상당한 제어입력을 요한다. 따라서 센서 잡음에 대한 영향을 충분히 고려할 필요가 있으므로, 노이즈를 많이 발생시키는 PWM방식의 직류모터 구동 드라이버보다는 선형 드라이버를 이용하는 것이 적절할 것으로 예상된다

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.123-130
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• 2022

During the past decades, detection of gear defects remains as a major problem, especially when the gears are subject to non-stationary phenomena. The idea of this paper is to mixture a multilevel wavelet transform with a fast EMD decomposition in order to early detect gear defects. The sensitivity of a kurtosis is used as an indicator of gears defect burn. When the gear is damaged, the appearance of a crack on the gear tooth disrupts the signal. This is due to the presence of periodic pulses. Nevertheless, the existence of background noise induced by the random excitation can have an impact on the values of these temporal indicators. The denoising of these signals by multilevel wavelet transform improves the sensitivity of these indicators and increases the reliability of the investigation. Finally, a defect diagnosis result can be obtained after the fast transformation of the EMD. The proposed approach consists in applying a multi-resolution wavelet analysis with variable decomposition levels related to the severity of gear faults, then a fast EMD is used to early detect faults. The proposed mixed methods are evaluated on vibratory signals from the test bench, CETIM. The obtained results have shown the occurrence of a teeth defect on gear on the 5th and 8th day. This result agrees with the report of the appraisal made on this gear system.

• 한국컴퓨터정보학회논문지
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• 제26권9호
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• pp.143-153
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• 2021

본 논문의 목적은 빠른 배송을 위한 배송 차량의 유연 회차와 크라우드쉬핑(Crowd Shipping) 배달원인 플렉스를 활용한 "유연 회차와 플렉스" 방식을 제안하고, 풀이 알고리즘을 제안하는 것이다. 알고리즘은 선행 연구에서 성능이 검증된 2-opt를 사용하여 차량 경로를 계산하고, 절약 휴리스틱(Saving heuristic)을 변형한 방식으로 플렉스에 할당할 고객을 계산한다. 알고리즘은 차량과 플렉스를 분리하는 것이 아니라, 상호 보완적으로 운용될 수 있게 한다. 이를 위해 차량 정보가 플렉스 할당 과정에 고려되도록 하였다. 본 연구의 실험은 다양한 도심지의 상황을 상정한 Random, Mixed, Cluster 인스턴스로 구성되었다. 실험 결과 모든 인스턴스에서는 플렉스의 사용이 차량 유연 회차의 효율성을 높여주는 것을 확인하였다. 또 플렉스와 배송 지연 시간 비용에 대한 민감도 분석에서는 "유연 회차와 플렉스"가 차량만을 사용하는 방식의 차량 대수에 따라 값에 차이를 보였지만, 플렉스 비용이나 배송 지연 시간 비용이 200% 증가하는 경우에도 우위를 유지하는 것을 확인하였다. 본 연구의 결과는 플렉스가 차량과 연계되어 활용되는 경우, 플렉스에 의해 서비스되는 고객뿐만 아니라 차량으로 서비스되는 고객들의 서비스 품질을 높일 수 있음을 보여준다.

• 대한간호학회지
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• 제43권5호
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• pp.579-586
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• 2013

Purpose: This article provides an update and overview of a nursing research program focused on understanding the pathophysiology and management of irritable bowel syndrome (IBS). Methods: This review includes English language papers from the United States, Europe, and Asia (e.g., South Korea) from 1999 to 2013. We addressed IBS as a health problem, emerging etiologies, diagnostic and treatment approaches and the importance of a biopsychosocial model. Results: IBS is a chronic, functional gastrointestinal disorder characterized by recurrent episodes of abdominal pain and alterations in bowel habit (diarrhea, constipation, mixed). It is a condition for which adults, particularly women ages 20-45, seek health care services in both the United States and South Korea. Clinically, nurses play key roles in symptom prevention and management including designing and implementing approaches to enhance the patients' self-management strategies. Multiple mechanisms are believed to participate in the development and maintenance of IBS symptoms including autonomic nervous system dysregulation, intestinal inflammation, intestinal dysbiosis, dietary intolerances, alterations in emotion regulation, heightened visceral pain sensitivity, hypothalamic-pituitary-adrenal dysregulation, and dysmotility. Because IBS tends to occur in families, genetic factors may also contribute to the pathophysiology. Patients with IBS often report a number of co-morbid disorders and/or symptoms including poor sleep. Conclusion: The key to planning effective management strategies is to understand the heterogeneity of this disorder. Interventions for IBS include non-pharmacological strategies such as cognitive behavior therapy, relaxation strategies, and exclusion diets.

• Industrial Engineering and Management Systems
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• 제13권4호
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• pp.398-407
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• 2014

Shortages and delays in a humanitarian logistics system can contribute to the pain and suffering of survivors or other affected people. Humanitarian logistics budgets should be sufficient to prevent such shortages or delays. Unlike commercial supply chain systems, the budgets for relief supply chain systems should be able to satisfy demand. This study describes a comprehensive model in an effort to satisfy the total relief demand by minimizing logistics operations costs. We herein propose a strategic model which determines the locations of distribution centers and the total inventory to be stocked for each distribution center where a flood or other catastrophe may occur. The proposed model is formulated and solved as a mixed-integer programming problem that integrates facility location and inventory decisions by considering capacity constraints and time restrictions in order to minimize the total cost of relief operations. The proposed model is then applied to a real flood case involving 47 disaster areas and 13 distribution centers in Thailand. Finally, we discuss the sensitivity analysis of the model and the managerial implications of this research.

• 전기학회논문지P
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• 제52권2호
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• pp.74-80
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• 2003

In this paper, a robust two-degree-of-freedom(TDF) the speed control system using $H_{\infty}$ optimization method and real genetic algorithm is proposed for the robust stability and the robust performance in dc servo motor system. This control system composed of feedback and feedforward controller. The feedback(FB) controller with $H_{\infty}$ optimization method is designed for real genetic algorithm that is model matching problem using mixed sensitivity function. The feedforward(FF) controller with $H_{\infty}$optimization method is minimized the error between transfer function of the optimal model and the overall transfer function. The proposed robust two-degree-of-freedom speed control system is simulated to the dc servo motor. By the simulation, feedback controller can obtain the robust stability property and feedforward controller can obtain the robust performance property under modelling error. The performance of the dc servo motor is analyzed by the experiment setting. The validity of the proposed method is verified through being compared with pid(proportional integrated differential)control system design method for the dc servo motor.

• Progress in Superconductivity
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• 제14권1호
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• pp.52-59
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• 2012

In this paper, the robust superconductor flywheel energy storage system(SFESS) controller using $H_{\infty}$ control theory was designed to damp low frequency oscillation of power system. The main advantage of the $H_{\infty}$ controller is that uncertainties of power system can be included at the stage of controller design. Both disturbance attenuation and robust stability for the power system were treated simultaneously by using mixed sensitivity $H_{\infty}$ problem. The robust stability and the performance for uncertainties of power system were represented by frequency weighted transfer function. To verify control performance of proposed SFESS controller using $H_{\infty}$ control, the closed loop eigenvalue and the damping ratio in dominant oscillation mode of power system were analyzed and nonlinear simulation for one-machine infinite bus system was performed under disturbance for various operating conditions. The results showed that the proposed $H_{\infty}$ SFESS controller was more robust than conventional power system stabilizer (PSS).