• 한국음향학회:학술대회논문집
• /
• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
• /
• pp.279-282
• /
• 2004

산조 가야금의 경우 몸체의 뒷판에 세 개의 구멍(공명혈)이 있다. 이 구멍은, 몸체를 일정한 부피를 가진 용기로 보았을 때, 그 용기의 입구의 단면적, 다시 말해, 헬름홀츠 공진기 (Helmholtz Resonator) 입구의 단면적과 같다. 본 논문에서는 이 공명혈의 역할을 알아보기 위해, 1) 우선 기성의 산조 가야금 몸체의 세 공명혈을 모두 막은 상태, 일부만 막은 상태, 열려있는 상태에서의 몸체의 충격응답 전달함수를 측정, 분석하여 개략적으로 알아보았고, 이어서 2) 뒷판에 구멍이 전혀 없는 실험용의 산조 가야금 몸체의 제작을 의뢰하여, 뒷판 중앙에 구멍을 점차적으로 넓게 뚫어가면서, 각 단계별로 몸체의 충격응답을 측정하여, 구멍의 크기와 몸체의 충격응답 전달특성 변화 간의 상관관계를 분석 해보았다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
• /
• pp.130-134
• /
• 2005

The objectives of this study are to improve the aerodynamics performance on the down-wind blade system with folding type blade which consists of the folding type rotor blade, wind vane yawing stabilizer and a bevel gearbox. The aerodynamics performance for the new wind turbine system are compared with those of the conventional up-wind blade system. In addition to, a novel multi voltage inverter system is applied for reductions of harmonic.

• 융합신호처리학회논문지
• /
• 제15권1호
• /
• pp.1-8
• /
• 2014

Digital watermarking techniques are attracting attention as a proper solution to protect copyright for multimedia data. This paper proposes a new audio watermarking method based on Discrete Cosine Transformation (DCT) and Discrete Wavelet Transformation (DWT) for copyright protection. In our proposed watermarking method, the original audio is transformed into DCT domain and divided into two parts. Synchronization code is applied on the signal in first part and 2 levels DWT domain is applied on the signal in second part. The absolute value of DWT coefficient is divided into arbitrary number of segments and calculates the energy of each segment and middle peak. Watermarks are then embedded into each middle peak. Watermarks are extracted by performing the inverse operation of watermark embedding process. Experimental results show that the hidden watermark data is robust to re-sampling, low-pass filtering, re-quantization, MP3 compression, cropping, echo addition, delay, and pitch shifting, amplitude change. Performance analysis of the proposed scheme shows low error probability rates.

• Journal of information and communication convergence engineering
• /
• 제21권2호
• /
• pp.110-116
• /
• 2023

Recently, as various examples of machine learning have been applied in the healthcare field, deep learning technology has been applied to various tasks, such as electrocardiogram examination and body composition analysis using wearable devices such as smart watches. To utilize deep learning, securing data is the most important procedure, where human intervention, such as data classification, is required. In this study, we propose a model that uses a clustering algorithm, namely, the K-means clustering, to label body fat according to gender and age considering body size aspects, such as chest circumference and waist circumference, and classifies body fat into five groups from high risk to low risk using a convolutional neural network (CNN). As a result of model validation, accuracy, precision, and recall results of more than 95% were obtained. Thus, rational decision making can be made in the field of healthcare or obesity analysis using the proposed method.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.229.2-229.2
• /
• 2014

Graphene, an allotrope of carbon, is a two-dimensional material having a unique electro-mechanical property that shows significant change of the electrical conductance under the applied strain. In addition of the extraordinary mechanical strength [1], graphene becomes a prospective candidate for pressure sensor technology [2]. However, very few investigations have been carried out to demonstrate characteristics of graphene sensor as a device form. In this study, we demonstrate a pressure sensor using graphene double layer as an active channel to generate electrical signal as the response of the applied vertical pressure. For formation of the active channel in the pressure sensor, two single graphene layers which are grown on Cu foil (25 um thickness) by the plasma enhanced chemical vapor deposition (PECVD) are sequentially transformed to the poly-di-methyl-siloxane (PDMS) substrate. Dry and wet transfer methods are individually employed for formation of the double layer graphene. This sensor geometry results a switching characteristic which shows ~900% conductivity change in response to the application of pulsed pressure of 5 kPa whose on and off duration is 3 sec. Additionally, the functional reliability of the sensor confirms consistent behavior with a 200-cycle test.

• 전력전자학회논문지
• /
• 제27권3호
• /
• pp.228-236
• /
• 2022

The charging methods of electric vehicles are divided into wired charging and wireless charging. Restrictions on the use of charging infrastructure for wireless charging vehicles currently exist because most charging infrastructure uses the wired charging method. Thus, wired and wireless integrated charging system has been studied. In this system, a wireless charging system especially requires a control method for high-efficiency operation in consideration of a change in a coupling coefficient. Therefore, this paper introduces two control methods for the high-efficiency operation of wireless charging that can be applied to wired and wireless integrated charging systems. In addition, loss analysis is performed through PSIM simulation to select a more advantageous method for high-efficiency operation among the two control methods. To verify the simulation-based loss analysis result, the two control methods are applied to the actual wireless charging system, and the efficiency is compared through the experiments Based on the experimental results, a control method suitable for high-efficiency operation of the wireless charging method is selected.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.507-510
• /
• 2005

Brake judder, which occurs when brakes are suddenly applied to a vehicle driving at high speed, affects the driver's safety to a great extent. It also has a low frequency that drivers can easily feel. Among theses presented, none offered studies using modeling of actual brakes in computer simulation in order to recreate the brake judder phenomenon, and most of them directly applied the frequency generated by the judder. To resolve this issue, this study hopes to develop a computer model that can recreate the phenomenon of brake judder. In this paper, in order to examine the vibration problem occurring when brake is applied on the test car, the multibody dynamic analysis program ADAMS was used to develop a computer model that can recreate the actual braking mechanism while breaking away from the existing understanding of brakes. Thus the existence of the brake judder phenomenon due to DTV(Dist Thickness Variation) and wheel rotating speed was examined through the developed model.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2022년도 제66차 하계학술대회논문집 30권2호
• /
• pp.31-34
• /
• 2022

본 논문에서는 손목 부착형 웨어러블(Wearable) RGB 카메라를 통해 취득한 손 이미지에 최적화된 손 자세 추정모델과 학습방법을 제안한다. 최근 의료분야에서 활발하게 인공지능이 사용되고 있으며 그 중 이미지 인식을 중심으로 하는 진단 분야[1]가 괄목할만한 성과를 보인다. 본 연구에서는 웨어러블 카메라를 통해 얻은 손 자세를 활용하여 질병 진단에 적용할 계획이다. 또한, 본 연구수행을 통해 질병진단에 필요한 데이터 측정비용 절감 및 개인 맞춤형 진단서비스를 제공할 것으로 기대된다.

• International Journal of Contents
• /
• 제12권3호
• /
• pp.22-28
• /
• 2016

Tensor with missing or incomplete values is a ubiquitous problem in various fields such as biomedical signal processing, image processing, and social network analysis. In this paper, we considered how to reconstruct a dataset with missing values by using tensor form which is called tensor completion process. We applied Tucker factorization to solve tensor completion which was built base on optimization problem. We formulated the optimization objective function using components of Tucker model after decomposing. The weighted least square matric contained only known values of the tensor with low rank in its modes. A first order optimization method, namely Nonlinear Conjugated Gradient, was applied to solve the optimization problem. We demonstrated the effectiveness of the proposed method in EEG signals with about 70% missing entries compared to other algorithms. The relative error was proposed to compare the difference between original tensor and the process output.

• 한국응용곤충학회:학술대회논문집
• /
• 한국응용곤충학회 2001년도 합동 춘계 학술발표회
• /
• pp.61-61
• /
• 2001