• 한국항공우주학회지
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• 제30권7호
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• pp.123-129
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• 2002

본 논문은 실제 저궤도 위성에서 GPS를 이용하여 궤도를 추정하는 연구 결과를 담고 있다. 우리별 3호의 GPS 수신기가 실제 측정한 3차원 위치 및 속도 정보를 이용하였으며, 추정 알고리즘으로는 실시간 계산을 위한 확장 칼만필터와 후처리를 위한 스무더를 사용하였다. 스무더는 확장 칼만필터를 통과한 값을 이용하여 다시 역으로 추정하는 과정을 거치게 되므로 전체적으로 안정화된 추정값을 제공한다. 본 논문에서는 스무더를 적용한 추정값을 이용하여 우리별 3호의 케플러 궤도 요소를 계산하고, 분석하였다.

• 수산경영론집
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• 제53권3호
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• pp.85-101
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• 2022

This study analyzed the performance of the national fishing port development project, which lacked ex-post impact evaluation despite a lot of investment in terms of fishery income opportunities. Using micro data from the Census of Agriculture, Forestry, and Fisheries, the sales amount of fishery products and the proportion of fishery-related businesses were used as performance indicators. The fishery households in the fishing port area (treatment group) and those not in the area (control group) were classified through data pre-processing, and factors unrelated to the fishing ports were controlled using the propensity score matching difference-in-difference method. The analysis target is six fishing ports with large investment in from 2010 to 2014. As a result of the analysis, it was confirmed that the sales of fishery products increased significantly in four of the six fishing ports, and the proportion of fishery-related businesses increased in two fishing ports. The analysis method of this study can be fully utilized in the evaluation of the Fishing Community New Deal 300 Project, which is in need of performance analysis.

• Journal of Positioning, Navigation, and Timing
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• 제13권1호
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• pp.103-110
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• 2024

In this paper, a test bed for real-time network Real-Time Kinematic (RTK) research was constructed using reference stations of the NGII. A group of candidate station networks was derived, including three stations in Seoul. The group consisted of four stations with a distance of less than 100 km between them. Among several candidates, a network composed of stations with short distances between them and demonstrating good data quality for all reference stations was selected as the test bed. After collecting real-time data in Radio Technical Committee for Maritime services (RTCM) format from the selected stations and conducting a noise analysis on measurements, mm-level carrier phase measurement noise was confirmed. Afterwards, the user set the reference station inside the test bed and analyzed the network RTK positioning performance of the MAC method using the GPS L1 frequency as post-processing. From the result of the analysis it was confirmed that the residual error for all users was within 10 cm after applying the correction. Additionally, after determining integer ambiguities through Least-squares AMBiguity Decorrelation Adjustment (LAMBDA), it was confirmed that the fix rate was 100%, and all ambiguities were resolved as true values.

• Journal of information and communication convergence engineering
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• 제22권2호
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• pp.145-152
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• 2024

Closed quotient (CQ) represents the time ratio for which the vocal folds remain in contact during voice production. Because analyzing CQ values serves as an important reference point in vocal training for professional singers, these values have been measured mechanically or electrically by either inverse filtering of airflows captured by a circumferentially vented mask or post-processing of electroglottography waveforms. In this study, we introduced a novel algorithm to predict the CQ values only from audio signals. This has eliminated the need for mechanical or electrical measurement techniques. Our algorithm is based on a gated recurrent unit (GRU)-type neural network. To enhance the efficiency, we pre-processed an audio signal using the pitch feature extraction algorithm. Then, GRU-type neural networks were employed to extract the features. This was followed by a dense layer for the final prediction. The Results section reports the mean square error between the predicted and real CQ. It shows the capability of the proposed algorithm to predict CQ values.

• 한국항공우주학회지
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• 제31권6호
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• pp.96-101
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• 2003

과학로켓3호(KSR-III) 비행시험시에 탑재용 원격측정장치는 로켓의 서브시스템들의 실시간 상태 및 각종 센서 자료를 획득하여 무선으로 전파 통신을 하고 지상에서 로켓을 추적하면서 비행중인 원격측정 데이터를 실시간으로 획득하고 복원하는 것은 로켓의 비행을 분석하는데 필수적이다. 또한 실시간으로 자료처리된 원격측정자료들은 네트워크를 통해 임무통제센터로 보내져 로켓의 비행 궤도를 도시하고 동시에 비행통제원이 로켓의 비행종단명령을 수행하기 위한 중요한 판단자료를 제공한다. 본 논문에서는 과학로켓3호 비행시험에 적합한 원격측정 수신과 관련된 운용기법 및 실시간 자료처리 시스템 개발에 관하여 기술하였으며 원격측정 수신결과를 분석하였다. 실제 비행시험시에 성공적으로 원격측정 수신 및 실시간 자료처리 임무를 완수하였다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제26권10호
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• pp.1156-1166
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• 1999

의사결정 시스템은 전사적인 의사결정과 전략적 정보수집을 위해 거대한 량의 정보를 빠른 시간내에 제공할 것을 요구한다. 데이타 웨어하우스는 이러한 정보를 신속히 제공하기 위해 여러 지역 데이타베이스로부터 필요한 정보를 사전에 추출하고 가공 및 통합하여 별도의 저장공간에 저장한다. 일반적으로, 웨어하우스 내의 정보는 지역 데이타베이스에 저장된 정보에 대한 실체화된 뷰로서 간주하며 지역 데이타의 변경에 따라 일관성을 유지하도록 반영해야 한다. 본 논문에서는 일관성을 유지하기 위해 정보 공유가 가능한 데이타 웨어하우스 시스템의 구조와 비-보상 실체 뷰 관리 기법을 제안한다. 본 논문에서 제안한 데이타 웨어하우스 시스템의 구조는 지역 데이타베이스에서 추출된 정보를 관리하는 별도의 지역 정보 관리자를 두어 뷰 관리자들 간의 정보 공유가 가능하게 한다. 비-보상 실체 뷰 관리 기법은 지역 데이타 변경 사건에 따른 뷰 관리 시 다른 사건에 의해 영향을 받지 않도록 하기 때문에 기본의 사전 보상이나 나중 보상 기법과는 달리 추가적인 질의 처리를 요구하지 않는 기법이다.Abstract A decision support system(DSS) commonly requires fast access to tremendous volume of information. A data warehouse is a database storing the information that is extracted, filtered and integrated from several relevant local databases to reply upon aggregated queries. The information stored in the data warehouse can be regarded as materialized views. The materialized view has to be modified according to the change of the corresponding local databases to preserve the data consistency. In this paper, we propose a data warehousing system architecture allowing information sharing (DAWINS), and a non-compensating materialized view maintenance algorithm(NCA). DAWINS architecture allows relevant information to be shared by individual view managers with local data manager for each local database. Unlikely to the pre- or post-compensating algorithms, which are required to remove the effects of some events to other view in the process of view maintenance, NCA does not require any additional query processing, since a local data manager in DAWINS already maintains the effects of update events occurring in local systems.

• 대기
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• 제32권3호
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• pp.179-189
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• 2022

The purpose of this study is to build and evaluate a high-resolution (50 m) KMAPP (Korea Meteorological Administration Post Processing) reflecting building data. KMAPP uses LDAPS (Local Data Assimilation and Prediction System) data to detail ground wind speed through surface roughness and elevation corrections. During the detailing process, we improved the vegetation roughness data to reflect the impact of city buildings. AWS (Automatic Weather Station) data from a total of 48 locations in the metropolitan area including Seoul in 2019 were used as the observation data used for verification. Sensitivity analysis was conducted by dividing the experiment according to the method of improving the vegetation roughness length. KMAPP has been shown to improve the tendency of LDAPS to over simulate surface wind speeds. Compared to LDAPS, Root Mean Square Error (RMSE) is improved by approximately 23% and Mean Bias Error (MBE) by about 47%. However, there is an error in the roughness length around the Han River or the coastline. Accordingly, the surface roughness length was improved in KMAPP and the building information was reflected. In the sensitivity experiment of improved KMAPP, RMSE was further improved to 6% and MBE to 3%. This study shows that high-resolution KMAPP reflecting building information can improve wind speed accuracy in urban areas.

• The Journal of Advanced Prosthodontics
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• 제15권3호
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• pp.145-154
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• 2023

PURPOSE. The objective of this study was to investigate how internal structures influence the overall and marginal accuracy of full arch preparations fabricated through additive manufacturing in different printing systems. MATERIALS AND METHODS. A full-arch preparation digital model was set up with three internal designs, including solid, hollow, and grid. These were printed using three different resin printers with nine models in each group. After scanning, each data was imported into the 3D data processing software together with the master cast, aligned and trimmed, and then put into the 3D data analysis software again to compare the overall and marginal deviation whose results are expressed using root mean square values and color maps. To evaluate the trueness of the resin model, the test data and reference data were compared, and the precision was evaluated by comparing the test data sets. Color maps were observed for qualitative analysis. Data were statistically analyzed by one-way analysis of variance and Bonferroni method was used for post hoc comparison (α = .05). RESULTS. The influence of different internal structures on the accuracy of 3D printed resin models varied significantly (P < .05). Solid and grid models showed better accuracy, while the hollow model exhibited poor accuracy. The color maps show that the resin models have a tendency to shrink inwards. CONCLUSION. The internal structure design influences the accuracy of the 3D printing model, and the effect varies in different printing systems. Irrespective of the kind of printing system, the printing accuracy of hollow model was observed to be worse than those of solid and grid models.

• 한국통신학회논문지
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• 제39A권12호
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• pp.764-770
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• 2014

불규칙 매체를 투과하는 광학적 이미징 시스템은 피부나 생물학적 조직등의 내부를 비침습적 이미징 기법을 사용해 관찰할 수 있게 해줄 것으로 큰 기대를 받고 있다. 불규칙 매체를 통한 이미징은 대개 불규칙 매체의 투과 특성을 전달 행렬로 모델링 및 측정하고, 측정된 전달 행렬을 사용하여 이미지를 복구하는 방식을 사용한다. 이러한 전달 행렬 기반의 이미징 방법은 많은 양의 데이터를 측정 하고 후 신호 처리를 해야 한다는 어려움을 가지고 있다. 최근에는, 이 데이터 획득 문제를 압축센싱이라는 방법을 사용해 해결할 수 있다는 결과들이 있었다. 압축센싱은 상대적으로 새로운 신호 획득 및 복구 체계로써 아주 적은 양의 신호 측정만으로도 신호를 정확하게 복구해 낼 수 있다. 본 논문에서는 불규칙 매체를 통과하는 이미징에서의 전달 행렬 기반의 이미지 복구 방법이 검토되며, 또한 압축센싱을 사용한 최신 연구 동향을 소개하고자 한다.

• 전자공학회논문지
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• 제50권7호
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• pp.140-148
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• 2013

본 논문은 100 Gb/s급 광통신 시스템을 위한 반복적인 Bose-Chaudhuri-Hocquenghem (BCH) 부호와 고성능 복호기 구조를 보여준다. 제안된 구조는 고속 데이터 처리율뿐만 아니라 뛰어난 오류정정능력을 보여준다. 제안된 6회 반복 i-BCH 복호기는 메모리 기반의 인터리브 기술을 이용하였으며 6번의 반복 복호시 $10^{-15}$ post-FEC Bit Error Rate(BER) 기준 9.34 dB의 강력한 Net Coding Gain(NCG) 성능을 제공한다. 제안된 고성능 i-BCH 복호기의 구조는 90-nm CMOS 공정을 사용하여 합성한 후 수행한 성능 분석 결과 430 MHz의 동작 속도와 100 Gb/s의 데이터 처리율을 갖는다. 따라서 100 Gb/s급 광통신시스템을 위한 차세대 순방향 오류정정 구조에 적용할 수 있다.