• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.821-832
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• 2011

Recently, the noise of vehicle is the one of the key factors for customers to purchase a vehicle and the most important part which is related to the noise is the exhaust system. Thus, car makers have their own ways to assess this exhaust noise not only to decrease the level of noise but to enhance the feeling of it. Typically, to do these things in the early stage of development, the tuning code of the exhaust system has to be made by CAE tool, which is very reliable but expensive, and the prototype parts of this code would be made for the validation test. Then this process can be iterated to meet the target of the performance. In this study, a new algorithm which adapts the '3 dimensional convective sound wave theory 'and 'Doppler effect' has been developed. With this new algorithm, a brand new system for the calculation of tail pipe noise has been developed and validated by acoustic wind tunnel test. As a result of this study, various comparisons and have been carried out, for example, the comparison with other CAE tool has been performed for the validity and the improvement of the new calculation code could be achieved.

• 한국컴퓨터정보학회논문지
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• 제12권2호
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• pp.77-82
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• 2007

본 논문에서는 콘크리트 표면 균열의 방향성을 효율적으로 인식하기 위하여 영상처리 기법을 적용하여 균열을 자동으로 검출하고 개선된 Max-Min 신경망을 제안하여 균열의 방향성을 자동으로 인식하는 기법을 제안한다. 균열 영상에서 빛의 영향을 효율적으로 보정하기 위해 모폴로지 기법인 채움 연산을 적용하고 Sobel 마스크를 적용하여 균열의 에지를 추출한 후, 반복 이진화를 적용하여 균열 영상을 이진화한다. 이진화된 균열 영상에서 2차례에 걸쳐 잡음 제거 연산을 수행한 후, 균열을 추출한다. 본 논문에서는 Max-Min 신경망을 개선하여 추출된 균열의 방향성을 자동으로 인식한다. 개선된 Max-Min 신경망은 delta-bar-delta 알고리즘을 적용하여 학습률을 자동으로 조정한다. 실제 콘크리트 표면 균열 영상을 대상으로 실험한 결과, 개선된 Max-Min 신경망이 균열의 방향성 인식에 효율적임을 확인하였다.

• 한국재료학회지
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• 제22권5호
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• pp.243-248
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• 2012

ZrN nanoparticles were prepared by an exothermic reduction of $ZrCl_4$ with $NaN_3$ in the presence of NaCl flux in a nitrogen atmosphere. Using a solid-state combustion approach, we have demonstrated that the zirconium nitride nanoparticles synthesis process can be completed in only several minutes compared with a few hours for previous synthesis approaches. The chemistry of the combustion process is not complex and is based on a metathesis reaction between $ZrCl_4$ and $NaN_3$. Because of the low melting and boiling points of the raw materials it was possible to synthesize the ZrN phase at low combustion temperatures. It was shown that the combustion temperature and the size of the particles can be readily controlled by tuning the concentration of the NaCl flux. The results show that an increase in the NaCl concentration (from 2 to 13 M) results in a temperature decrease from 1280 to $750^{\circ}C$. ZrN nanoparticles have a high surface area (50-70 $m^2/g$), narrow pore size distribution, and nano-particle size between 10 and 30 nm. The activation energy, which can be extracted from the experimental combustion temperature data, is: E = 20 kcal/mol. The method reported here is self-sustaining, rapid, and can be scaled up for a large scale production of a transition metal nitride nanoparticle system (TiN, TaN, HfN, etc.) with suitable halide salts and alkali metal azide.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.63-74
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• 2014

Predicting protein loop structures is an important modeling problem since protein loops are often involved in diverse biological functions by participating in enzyme active sites, ligand binding sites, etc. However, loop structure prediction is difficult even when structures of homologous proteins are known due to large sequence and structure variability among loops of homologous proteins. Therefore, an ab initio approach is necessary to solve loop modeling problems. One of the difficulties in the development of ab initio loop modeling method is to derive an accurate scoring function that closely approximates the true free energy function. In particular, entropy as well as energy contribution have to be considered adequately for loops because loops tend to be flexible compared to other parts of protein. In this study, the contribution of conformational entropy is considered in scoring loop conformations by employing "colony energy" which was previously proposed to estimate the free energy for an ensemble of conformations. Loop conformations were generated by using two EDISON_Chem programs GalaxyFill and GalaxySC, and colony energy was designed for this sampling by tuning relevant parameters. On a test set of 40 loops, the accuracy of predicted loop structure improved on average by scoring with the colony energy compared to scoring by energy alone. In addition, high correlation between colony energy and deviation from the native structure suggested that more extensive sampling can further improve the prediction accuracy. In another test on 6 ligand-binding loops that show conformational changes by ligand binding, both ligand-free and ligand-bound states could be identified by using colony energy when no information on the ligand-bound conformation is used.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5179-5196
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• 2019

To explore an effective non-invasion medical imaging diagnostics approach for hepatocellular carcinoma (HCC), we propose a method based on adopting the multiple technologies with the multi-parametric data fusion, transfer learning, and multi-scale deep feature extraction. Firstly, to make full use of complementary and enhancing the contribution of different modalities viz. multi-parametric MRI images in the lesion diagnosis, we propose a data-level fusion strategy. Secondly, based on the fusion data as the input, the multi-scale residual neural network with SPP (Spatial Pyramid Pooling) is utilized for the discriminative feature representation learning. Thirdly, to mitigate the impact of the lack of training samples, we do the pre-training of the proposed multi-scale residual neural network model on the natural image dataset and the fine-tuning with the chosen multi-parametric MRI images as complementary data. The comparative experiment results on the dataset from the clinical cases show that our proposed approach by employing the multiple strategies achieves the highest accuracy of 0.847±0.023 in the classification problem on the HCC differentiation. In the problem of discriminating the HCC lesion from the non-tumor area, we achieve a good performance with accuracy, sensitivity, specificity and AUC (area under the ROC curve) being 0.981±0.002, 0.981±0.002, 0.991±0.007 and 0.999±0.0008, respectively.

• 한국전자파학회논문지
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• 제11권6호
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• pp.920-928
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• 2000

본 논문은 tpo로이 제안된 안테나 소형화 기법을 이용하여 비교적 높은 이득과 광대역 특성을 지닌 마이크로 스트립 패치 안테나 (microstri patch antenna)를 개구 결합성 급전구조 (aperture coupled feed)를 이용하여 셀룰러 대역의 (824~894MHz) 중계기용으로 설계 및 제작되었다. 새로이 제안된 방법에서는 안테나의 크기를 줄이기 위하여 구형 마이크로스트립 패치 아테나의 TM01 모드의 전계분포를 이용하여 전계분포가 가장 큰 패치의 가장자리 아랫부분에 공진 패치의 길이 방향으로 유전체를 상빙하여 안테나의 크기를 효율적으로 줄이고 유전율이 높아짐으로써 발생되는 안테나의 이득 감소를 최소화 시킴과 동시에 소형 경량의 안테나를 쉽게 제작할수 있도록 설계 제작하였다. 또한 under-coupling 기법과 정합회로를 사용하여 셀룰러대역의 전대역에서 제작할 수 있도록 제작하였다. 또한 under-coupling 기법과 정합회로를 사용하여 셀룰러대역의 전 대역에서 VSWR이 1,5:1 이하가 되도록 설계하였다. 안테나 설계 툴 (Tool)은 Agilent Technologies사의 HFSS를 사용하였다.

• Structural Engineering and Mechanics
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• 제66권2호
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• pp.217-227
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• 2018

In the last decades, valuable results have been reported regarding conventional passive, active, semi-active, and hybrid structural control systems on two-dimensional and a few three-dimensional shear buildings. In this research, using a three-dimensional finite element model of high-rise concrete structures, designed by performance based plastic design method, it was attempted to construct a relatively close to reality model of concrete structures equipped with Tuned Mass Damper (TMD) by considering the effect of soil-structure interaction (SSI), torsion effect, hysteresis behavior and cracking effect of concrete. In contrast to previous studies which have focused mainly on linearly designed structures, in this study, using performance-based plastic design (PBPD) design approach, nonlinear behavior of the structures was considered from the beginning of the design stage. Inelastic time history analysis on a detailed model of twenty-story concrete structure was performed under a far-field ground motion record set. The seismic responses of the structure by considering SSI effect are studied by eight main objective functions that are related to the performance of the structure, containing: lateral displacement, acceleration, inter-story drift, plastic energy dissipation, shear force, number of plastic hinges, local plastic energy and rotation of plastic hinges. The tuning problem of TMD based on tuned mass spectra is set by considering five of the eight previously described functions. Results reveal that the structural damage distribution range is retracted and inter-story drift distribution in height of the structure is more uniform. It is strongly suggested to consider the effect of SSI in structural design and analysis.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.35-38
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• 2014

Herein, we report on the preparation of red fluorescent Si nanoparticles stabilized with styrene. Nano-sized Si particles emit fluorescence under UV excitation, which could be used to open up new applications in the fields of optics and semi-conductor research. Unfortunately, conventional methods for the preparation of red fluorescent Si nanoparticles suffer from the lack of a fully-established standard synthesis protocol. A common initial approach during the preparation of semi-conductors is the etching of crystalline Si wafers in a HF/ethanol/$H_2O$ bath, which provides a uniformly-etched surface of nanopores amenable for further nano-sized modifications via tuning of various parameters. Subsequent sonication of the etched surface crumbles the pores on the wafer, resulting in the dispersion of particles into the solution. In this study, we use styrene to occupy these platforms to stabilize the surface. We determine that the liberated silicon particles in ethanol solution interact with styrene, resulting in the substitution of Si-H bonds with those of Si-C as determined via UV photo-catalysis. The synthesized styrene-coated Si nanoparticles exhibit a stable, bright, red fluorescence under excitation with a 365 nm UV light, and yield approximately 100 mg per wafer with a synthesis time of 2 h. We believe this protocol could be further expanded as a cost-effective and high-throughput standard method in the preparation of red fluorescent Si nanoparticles.

• 대한전자공학회논문지TC
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• 제46권10호
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• pp.57-62
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• 2009

본 논문은 방사선 피폭량을 실시간으로 산출하기 위해 무선전력 전송용 13.56MHz의 안테나 설계를 위한 안테나 회로의 최적화 및 수치적 해석을 연구하였다. 리더기(Reader)에서 테크(Tag)로 무선으로 전력을 전송하기 위해서 안테나 주파수 대역 중 13.56MHz는 유도 전류를 이용한 루프 안테나에 많이 이용하고 있다. 본 논문은 전자유도 방식의 원리를 이용해 안테나 LC 공진을 위한 수치적 계산을 통해 L과 C 값을 산출하여 실제 측정치와의 값과 비교하였다. 또한 안테나 회로의 최적화 튜닝 및 안테나 포트의 매칭을 위해 공진(Resonance)용 캐패시터를 가변하여 스코프로 안테나 코일으 양단의 전압이 최고시점을 관측하여 공진점을 찾아 보았다. 이러한 실험은 무선으로 전력을 공급 받을 수 있는 무선전력 전송 시스템에 응용되어 매우 유용하게 활용될 것으로 기대된다.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.376-383
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• 2012

A number of scientific researches are currently being conducted on the potential health hazards of power frequency electric and magnetic field (EMF). There exists a non-objective and psychological belief that they are harmful, although no scientific and objective proof of such exists. This possible health risk from ELF magnetic field (MF) exposure, especially for children under 17 years of age, is currently one of Korea's most highly contested social issues. Therefore, to assess the magnetic field exposure levels of those children in their general living environments, the personal MF exposure levels of 436 subjects were measured for about 6 years using government funding. Using the measured database, estimation formulas were developed to predict personal MF exposure levels. These formulas can serve as valuable tools in estimating 24-hour personal MF exposure levels without directly measuring the exposure. Three types of estimation formulas were developed by applying evolutionary computation methods such as genetic algorithm (GA) and genetic programming (GP). After tuning the database, the final three formulas with the smallest estimation error were selected, where the target estimation error was approximately 0.03 ${\mu}T$. The seven parameters of each of these three formulas are gender (G), age (A), house type (H), house size (HS), distance between the subject's residence and a power line (RD), power line voltage class (KV), and the usage conditions of electric appliances (RULE).