• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제38권1호
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• pp.38-43
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• 2012

Introduction: The location of parotid gland tumors in the superficial or deep lobes can affect the time and difficulty of operations. Therefore, accurate preoperative evaluation of the tumor location is important for surgical outcomes. Materials and Methods: A total of 16 patients with parotid gland tumors and who underwent a parotidectomy between April 2003 and March 2011 were retrospectively reviewed in terms of demographic background, tumor location, surgical treatment, and treatment outcomes. Tumor location was estimated by four landmarks on contrast enhanced computerized tomography scans, which were Conn's arc, the facial nerve (FN) line, the Utrecht line, and the retromandibular vein. Tumor location was confirmed by relative position depending on the facial nerve during surgery. It was assumed positive since the tumor lies in the superficial lobe of the parotid gland, the sensitivity, specificity, positive predictive value, negative predictive value, and efficiency of each landmark were evaluated. Results: Our result revealed that the facial nerve line had a sensitivity of 83.3%, specificity of 100%, positive predictive value of 100%, negative predictive value of 71.4%, and efficiency of 87.5%. Some would be more efficient preoperative evaluation methods of the relationship of parotid gland tumors to the facial nerve than others. Conclusion: In our study, the FN line was found to be the most reliable analysis method.

• Journal of Welding and Joining
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• 제30권6호
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• pp.126-132
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• 2012

The GMA welding process involves large number of interdependent variables which may affect product quality, productivity and cost effectiveness. The relationships between process parameters for a fillet joint and bead geometry are complex because a number of process parameters are involved. To make the automated GMA welding, a method that predicts bead geometry and accomplishes the desired mechanical properties of the weldment should be developed. The developed method should also cover a wide range of material thicknesses and be applicable for all welding position. For the automatic welding system, the data must be available in the form of mathematical equations. In this study a new intelligent model with genetic algorithm has been proposed to investigate interrelationships between welding parameters and bead geometry for the automated GMA welding process. Through the developed model, the correlation between process parameters and bead geometry obtained from the actual experimental results, predicts that data did not show much of a difference, which means that it is quite suitable for the developed genetic algorithm. Progress to be able to control the process parameters in order to obtain the desired bead shape, as well as the systematic study of the genetic algorithm was developed on the basis of the data obtained through the experiments in this study can be applied. In addition, the developed genetic algorithm has the ability to predict the bead shape of the experimental results with satisfactory accuracy.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.2107-2118
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• 2020

The nuclear reactor coupled with supercritical carbon dioxide (S-CO₂) Brayton cycle has good prospects in generation IV reactors. Turbomachineries (turbine and compressor) are important work equipment in circulatory system, whose performances are critical to the efficiency of the energy conversion system. However, the sharp variations of S-CO₂ thermophysical properties make turbomachinery performances more complex than that of traditional working fluids. Meanwhile, almost no systematic analysis has considered the effects of turbomachinery efficiency under different conditions. In this paper, an in-house code was developed to realize the geometric design and performance prediction of S-CO₂ turbomachinery, and was coupled with systematic code for Brayton cycle characteristics analysis. The models and methodology adopted in calculation code were validated by experimental data. The effects of recompressed fraction, pressure and temperature on S-CO₂ recompression Brayton cycle were studied based on detailed design of turbomachinery. The results demonstrate that the recompressed fraction affects the turbomachinery characteristic by changing the mass flow and effects the system performance eventually. By contrast, the turbomachinery efficiency is insensitive to variation in pressure and temperature due to almost constant mass flow. In addition, the S-CO₂ thermophysical properties and the position of minimum temperature difference are significant influential factors of cyclic performance.

• 지적과 국토정보
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• 제46권1호
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• pp.133-148
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• 2016

다양한 산업에서 드론의 활용 가능성이 높아지는 추세에 따라 무인기 관련 법 개정에 대한 요구가 커지고 있다. 그러나 현재 드론은 조종사의 비행 조건 및 운용 범위가 엄격하게 제한되고 가시 환경 하에서만 운용이 가능하므로, 택배 등의 산업에는 활용이 어렵다. 따라서 다양한 산업에서의 드론 활용 가능성을 높이기 위해서는 위치정확도 향상은 물론이고, 무인기의 충돌을 방지하고, 위험요소를 회피하기 위한 적절한 보호수준(Protection Level)을 계산하는 것이 필수적이다. 보호수준을 포함한 무결성 정보는 SBAS(Satellite Based Augmentation Systm) 시스템을 이용한 보강항법 수행을 통해 산출할 수 있으며, 이를 통해 GPS(Global Positioning System) 단독측위가 가지는 한계를 보완할 수 있다. 이에 따라 본 논문에서는 LAAS(Local Area Augmentation System) 착륙 카테고리별 결심고도를 기준으로 드론의 비행고도를 설정하여, GPS 단독측위와 SBAS 보강항법 수행 시의 하루 중 항법수행 가능 시간의 비율을 비교하는 시뮬레이션을 수행하였다.

• 오토저널
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• 제13권2호
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• pp.67-87
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• 1991

The computer program which predicts the gas exchange process of multi-cylinder 4-Stroke cycle spark-ignition engine, can be great assistance for the design and development of new engine. In this study, the computer program was developed to predict the gas exchange process of multi-cylinder four stroke cycle spark ignition engine including intake and exhaust systems. When gas exchange process is to be calculated, the evaluation of the variation of the thermo-dynamic properties with time and position in the intake and exhaust systems is required. For the purpose, the application of the generalized method of characteristics to the gas exchange process is known as one of the method. The simulation model developed was investigated to the analysis of the branch system of multi-cylinder. The models used were the 2-zone expansion model and single zone model for in cylinder calculation and the generalized method of characteristic including area change, friction, heat transfer and entropy gradients for pipe flow calculation. The empirical constants reduced to least number as possible were determined through the comparison with the experimented indicator diagram of one particular operation condition and these constants were applied to other operating condition. The predicted pressures in cylinder were compared with the experimental results over the wide range of equivalence ratio and ignition timing. The predicted values have shown good agreement with the experimental results. The thermodynamic properties in the intake and exhaust system were predicted over the wide range of equivalence ratio and ignition timing. The obtained results can be summarized as follows. 1. Pressures in the exhaust manifold have a little influence on the equivalence ratio, a great influence on the ignition timing. 2. Pressures in the inlet manifold are nearly unchanged by the equivalence ratio and the ignition timing. 3. In this study, the behaviors of the exhaust temperature, gas in the exhaust manifold were ascertained.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1133-1133
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• 2001

Fruit sweetness, as indexed by total soluble solids (TSS), and fruit acidity are key factors in the description of the fruit eating quality. Our group has been using short wave NIR spectroscopy (SW-NIR; 700-1100 nm) in combination with chemometric methods (PLS and MLR) for the non-invasive determination of the fruit eating quality (1,2). In order to further improve calibration performance, we have investigated SW-NIR spectra of sucrose and D-glucose. In previous reports on the band assignment for these sugars in the 1100-2500 nm spectral region (3-7), it has been established that change in concentration, temperature and physical state of sugars reflects on the shape and position of the spectral bands in the whole NIR region(5-7). The effect of change in concentration and temperature of individual sugar solutions and sugar spiked Juice samples was analysed using combined spectroscopic (derivative, difference, 2D spectroscopy) and linear regression chemometric (PLS, MLR) techniques. The results have been compared with the spectral data of a range of fruit types, varying in TSS content and temperature. In the 800-950 nm spectral region, the B-coefficients for apples, peaches and nectarines resemble those generated in a calibration of pure sucrose in water (Fig. 1). As expected, these fruits exhibit better calibration and prediction results than those in which the B-coefficients were poorly related to those for sugar.(Figure omitted).

• 한국정보처리학회논문지
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• 제3권1호
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• pp.144-152
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• 1996

스펙트럼 요구가 증가하고 무선국수가 급증함에 따라 같은 주파수를 공유 또는 재사용 가능성을 평가하는 기반기술인 스펙트럼 엔지니어링 기술에 관한 연구가 시급 히 요구되고 있다. 또한 무선기지국에 대한 서비스 영역이나 기자국 선정등 무선망 설계의 기반기술이 되는 전파분석 기술은 산악이 70%이상인 국내 전파환경상 외국의 연구결과와 치이점이 있을 수 있기 때문에 독자적으로 개발할 필요가 있다. 본 논문에 서는 ; 이 두 분야를 동시에 시뮬레이션 가능하도록 전체 구성요소를 제시하였으며, 국내 전파환경에 적합한 전파전파 예측모델을 제시함과 동시에 GIS(Geographic Information System)를 기반으로 무선 기지국 장소 선정을 현장감 있게 한 시뮬레이터 를 설계 및 구현하였다. 구현된 시뮬레이터를 이용하여 주파수할당, 치국설계, 무선 서비스범위 업무에 적용시킬 수 있음을 보였다. 그리고 전파분석 결과를 고찰해볼 때, 전파전파 예측치와 실측치의 오차는 표준편차 약 5∼7dB로서 실용성이 있다고 판단한다.

• 수산해양기술연구
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• 제32권4호
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• pp.331-339
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• 1996

본 연구에서는 해양목장에서 음향을 사용한 어군행동제어에 관한 기초적인 자료를 얻기 위하여, 감지하기 쉬운 주파수의 순음과 먹이의 조합으로 어류를 학습시켜서, 음향 순치의 가능성을 검토했다. 미차체장이 385~459mm인 수컷 8마리와 암컷 5마리를 실험 수조에 수용하여, 수조내에 설치한 수중 스피커로부터 감지하기 쉬운 200Hz의 순음을 방성하면서 원격급이 장치로부터 급이하여 조건학습을 실시했다. 학습과정을 수록한 비디오 영상으로부터 물고기의 행동을 해석하여 색이장에 출현하는 빈도를 방성 전.방성 중.방성 후로 나눠서 해석했다. 학습 개시 일로부터 8일째에 학습 음에 첫 반응을 보였으며, 4일간 학습을 중지한 후에 학습 음을 방성 하여도 반응을 보였다. 방성 후에 음원부근에 위집 하는 율이 방성 전보다 높아져서, 1분간의 평균 출현빈도는 51%였다.

• Journal of Biosystems Engineering
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• 제27권3호
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• pp.259-266
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• 2002

It is crucial to know spatial soil variability for precision farming. However, it is time-consuming, and difficult to measure spatial soil properties. Therefore, there are needs fur sensing technology to estimate spatial soil variability, and for electronic mapping technology to store, manipulate and process the sampled data. This research was conducted to develop a real-time soil organic matter sensor and an electronic mapping system. A soil organic matter sensor was developed with a spectrophotometer in the 900∼1,700 nm range. It was designed in a penetrator type to measure reflectance of soil at 15cm depth. The signal was calibrated with organic matter content (OMC) of the soil which was sampled in the field. The OMC was measured by the Walkeley-Black method. The soil OMCs were ranged from 0.07 to 7.96%. Statistical partial least square and principle component regression analyses were used as calibration methods. Coefficient of determination, standard error prediction and bias were 0.85 0.72 and -0.13, respectively. The electronic mapping system was consisted of the soil OMC sensor, a DGPS, a database and a makeshift vehicle. An algorithm was developed to acquire data on sampling position and its OMC and to store the data in the database. Fifty samples in fields were taken to make an N-fertilizer dosage map. Mean absolute error of these data was 0.59. The Kring method was used to interpolate data between sampling nodes. The interpolated data was used to make a soil OMC map. Also an N-fertilizer dosage map was drawn using the soil OMC map. The N-fertilizer dosage was determined by the fertilizing equation recommended by National Institute of Agricultural Science and Technology in Korea. Use of the N-fertilizer dosage map would increase precision fertilization up to 91% compared with conventional fertilization. Therefore, the developed electronic mapping system was feasible to not only precision determination of N-fertilizer dosage, but also reduction of environmental pollution.

• 한국항행학회논문지
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• 제20권5호
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• pp.417-424
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• 2016

러시아는 자국 내 위성기반 보강시스템의 서비스 제공을 위하여 최근 정지궤도 위성을 통하여 SDCM 신호를 송출하기 시작하였다. SDCM용 정지궤도 위성인 LUCH-5A와 LUCH-5B의 영향권에 포함되어 있는 한반도에서도 현재 테스트 중인 PRN (pseudo random number) 140번 메시지가 수신되고 있어 국내 SDCM의 적용 및 그 성능 분석이 가능하다. 본 논문에서는 수신된 SDCM 메시지를 남한 지역의 최북단에 위치한 국토지리정보원 철원 기준국에 적용하였고, 이를 통해 수평 0.8749 m, 수직 0.9589 m (RMS)으로 그 성능이 크게 향상됨을 확인하였다. 또한 GPS와 GLONASS를 동시에 보강하는 SDCM의 특성을 반영하여 분석한 결과, 다중 위성군의 SBAS가 GPS 단독 SBAS에 비해 보호수준은 약 30 % 감소시킴으로써, APV-I 가용성 증대에 기여함을 확인하였다. 이를 통해 다중 위성군의 SBAS가 국내 개발될 KASS 시스템의 성능 향상에 기여할 수 있음을 예측할 수 있다.