• Phonetics and Speech Sciences
• /
• v.7 no.4
• /
• pp.49-55
• /
• 2015

It is argued in this paper that, in determining semantic similarity, Korean words should be recategorized with a focus on the semantic relation to ontology in light of cross-linguistic morphological variations. It is proposed, in particular, that Korean semantic similarity should be measured on three tracks, human judgements track, relatedness track, and cross-part-of-speech relations track. As demonstrated in Yang et al. (2015), GloVe, the unsupervised learning machine on semantic similarity, is applicable to Korean with its performance being compared with human judgement results. Based on this compatability, it was further thought that the model's performance might most likely vary with different kinds of specific relations in different languages. An attempt was made to analyze them in terms of two major Korean-specific categories involved in their lexical and cross-POS-relations. It is concluded that languages must be analyzed by varying methods so that semantic components across languages may allow varying semantic distance in the vector space models.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.11a
• /
• pp.360-361
• /
• 2022

전자 해도 정보 시스템(ECDIS: Electronic Chart and Display Infomation System)에서 항로의 기준선에서 선박이 떨어져 있는 거리인 항로 이탈 거리(XTD: Cross Track Distance)를 구하기 위해서는 선박이 변침점 간의 몇 번째 경로에 있는지 판단해야 한다. 본 논문에서는 변침점 간 경로상의 순서를 파악하기 위하여 기존의 알고리즘과 수학적으로 같으며 계산량을 줄이는 새로운 접근법을 제시하였다. 그 결과로 기존보다 삼각함수 호출 수를 75%로 줄였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.791-796
• /
• 2011

In order to understand long range wave propagation in railway tracks, it is required to identify how far vibrations can travel along a rail. To answer this question, the attenuation characteristics of the main propagating waves are required as a function of distance. In this work, it is identified which wave types predominantly propagate on various regions of the rail cross-section. Then decay rates of propagating waves in railway tracks are investigated for frequencies up to 80 kHz. A numerical method called the Wavenumber Finite Element (WFE) method is utilized to predict dispersion curves and decay rates for a rail on a continuous foundation. In order to validate the simulated results, measurements have been performed on a test track and an operational railway track. The measured results are compared with the output of the simulations and good agreements are found between them.

• Journal of the Korean institute of surface engineering
• /
• v.30 no.6
• /
• pp.400-405
• /
• 1997

The experimental study has been performed to deposit to deposit chromia powder on magnssium alloy for tribological and mechanical properties. The optimal condition was obtained by changing the spray condition such as working distance and gun power. As ceramics was coated onto the a light metal such as Mg according to the weight reduection of the car engine block, it could acquire that the engine efficiency deu to the weight reduction and properties such as resistance to heat, as well as wear. Coating qualities are discussed with respect to hardness, tribologicalproperty, and microstructure. The tribological and mechanical properties are investigated by using the reciprocal configuration tribometer and microharduess tester. Wear mode is determined by observing the SEM morhpology of wear track and cross section view of wear track.

• Proceedings of KOSOMES biannual meeting
• /
• 2018.06a
• /
• pp.53-53
• /
• 2018

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2023.05a
• /
• pp.263-264
• /
• 2023

본 연구는 자율운항선박의 실제 해상에서의 성능 검증하기 위한 실험을 진행하였다. 먼저 SAS(Samsung Autonomous System)을 활용하여 시뮬레이션을 진행하였다. 시뮬레이션은 Imazu 조우 모델을 기반으로 실험을 진행하였다. 시뮬레이션에서 조우 선박은 2-4척으로 정면, 횡단, 추월 등이 뒤섞인 상황을 가정하였다. 결과 분석은 6가지 항목(속력, Heading, Rate of Turn, Collison Risk Index, DCPA, TCPA, Closest Distance, XTD(Cross-Track Distance))을 분석하였다. 2 차례의 실해역 실험을 진행하였다. 목포-제주도 구간에서 실해역 실험을 진행 후 목포-이어도-독도 항로에서 실해역 실험을 진행하였다. 실해역 실험 결과 Imazu 모델 기반 시뮬레이션과 비슷한 결과를 보였다.

• Journal of Navigation and Port Research
• /
• v.47 no.6
• /
• pp.386-393
• /
• 2023

Recently, the demand for autonomous navigation technology has increased, and related research is also increasing. Autonomous ships generally follow the planned route, calculate the avoidance route according to the risk situation while sailing, and follow a calculated route. In general, an automatic steering device is used to follow the route, and among the operational automatic steering device methods, the route control mode is the most appropriate method to apply to autonomous ships. Therefore, in this study, we developed a route-tracking algorithm to apply an avoidance route using the navigation control mode of an automatic steering device. The algorithm was developed by dividing the straight and turning sections. A performance test was conducted to satisfy the performance suggested by IEC 62065, the relevant international standard, using simulator equipment that had acquired international certification to verify its performance. The results of the performance verification confirmed that the cross-track error, which represents the straight distance between the ship and the route, satisfied the performance standards suggested by IEC 62065 when the ship followed the route.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.3
• /
• pp.311-318
• /
• 2018

In accordance with the stipulations of the STCW Convention, simulation training has been enforced in order to develop practical skills so as to prevent accidents by predetermining the risks in special marine environments. Simulation training is a useful way to acquire navigation abilities, and can continuously measure the ability of a trainee by applying an appropriate evaluation. However, the result of training is evaluated by the instructor's subjective judgment without quantitative criteria. Therefore, this study aims to quantitatively evaluate the effectiveness of simulation training. For this purpose, evaluation items were derived by analyzing legal standards, earlier studies, and the current status of MET institutions. The simulations were then performed three times in the same scenarios and analyzed the results. As a result, it has been shown that the objectively analyzed ability to keep the route and to make safe passage with other vessel, as well as subjectively evaluated ability by the apprentice officer has been improved as training progressed. Through the evaluation of simulation training results, it can be derived that simulation education needs supplementation, and can be provided as a basic form of data to quantify the evaluation results of the simulation training in the future.

• The KIPS Transactions:PartB
• /
• v.9B no.6
• /
• pp.707-714
• /
• 2002

This paper presents a real-time Hausdorff matching algorithm for tracking of moving object acquired from an active camera. The proposed method uses the edge image of object as its model and uses Hausdorff distance as the cost function to identify hypothesis with the model. To enable real-time processing, a high speed approach to calculate Hausdorff distance and half cross matching method to improve performance of existing search methods are also presented. the experimental results demonstrate that the proposed method can accurately track moving object in real-time.

• Tribology and Lubricants
• /
• v.11 no.5
• /
• pp.108-113
• /
• 1995

Wear and friction behavior of plasma-sprayed coatings in Mo- and Co-based alloy were studied for the application of piston-ring automobile engine. The plasma-sprayed coatings were varied with gun current density, gas flow, and distance. The surface roughness, microhardness, and wear volume were measured depending on the spray distances. The high temperature hardness value were also measured as a function of temperature. Ball-on-disc geometry configuration tribometer was utilized in air. The wear tests were performed in the temperature ranges from room temperature to 825$^{\circ}$C to investigate the tribological trend of the piston-ring materials in the lack of lubricant. The cross sections of wear track were investigated, using microscopy.