• 한국정보통신학회논문지
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• 제23권5호
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• pp.495-507
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• 2019

데이터 희소성은 추천 시스템의 주요 과제 중 하나이다. 추천 시스템에서는, 일부분만 관찰된 데이터이고 다른 부분은 데이터가 누락된 대용량 데이터를 포함하고 있다. 대부분의 연구에서는, 데이터 세트에서 무작위로 데이터가 누락되었다고 가정하고, 관찰된 데이터만을 사용하여 추천 모델을 학습함으로써 사용자에게 항목을 추천하고 있다. 그러나, 실제로는 누락된 데이터는 무작위로 손실되었다고 볼 수 없다. 본 연구에서는, 누락 된 데이터를 사용자적 관심의 부정적인 예라고 간주하였다. 또한, 3가지 샘플 접근 방식을 SVD++ 알고리즘과 결합하여 SVD++_W, SVD++_R 그리고 SVD++_KNN 알고리즘을 제안하였다. 실험결과를 통하여, 제안한 3가지 샘플 접근 방식이 기존의 기본적인 알고리즘 보다 Top-N 추천에서 정확성과 회수율을 효과적으로 향상시킬 수 있다는 것을 보였다. 특히, SVD++_KNN 가 가장 우수한 성능을 보였는데, 이는 KNN 샘플 접근 방식이 사용자적 관심의 부정적인 예를 추출하는데 가장 효율적인 방법이라는 것을 보여주었다.

• 한국기계가공학회지
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• 제9권2호
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• pp.12-19
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• 2010

The characteristics of the torsional systems are generally examined with the nonlinearities such as the several staged clutch damper springs, gear backlashes and drag torques. Generally speaking, the system's characteristics can be found out by the eigensolutions which can show the system natural frequencies and the mode shapes. However, these factors can not give the complete solutions to avoid the noise and vibration problems related to the nonlinear effects. Therefore, several assumptions should be made for solving the real physical system problems under the linear analysis which can reflect the nonlinear effects in the torsional system. This means that the several modified linear factors such as the modified clutch damper spring constants can be used to examine and avoid the natural frequency zones related to the noise and vibration problems. Under the linear analysis with the assumed and modified values, the system can be investigated with the more reliable ways for the realistic phenomena.

• KIEAE Journal
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• 제10권6호
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• pp.123-130
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• 2010

Indoor air quality has attracted great attention in recent years and thus the importance of managing finishing materials in terms of pollutant source control is being emphasized. Managing the finishing material at the design stage maximizes the efficiency of IAQ control at the following construction stage. However, there are insufficient investigations on the application of a specific finishing material management process, a database management system or a finishing material management process network. As a result, the main purposes of this study comprise comprehensive evaluation of IAQ performance from the selected finishing materials and auxiliary materials, application of the material management system basing on the types and characteristics of toxic substances generated from the indoor finishing materials, investigation of IAQ evaluation standard, and the overall IAQ evaluation method for the design parts. The result of this study will be the basic data to construct DBMS for management of finishing materials with respect to IAQ.

• 동의생리병리학회지
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• 제33권5호
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• pp.255-260
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• 2019

Oriental Diagnosis System(ODS) is an artificial intelligence program that utilize entered diagnosis knowledge, determine patient's disease and decide right medicine. The purpose of this study is to find a correlation between pattern Identification in Korean medicine and each sasang types(So-Yang, So-Eum and Tae-Eum) by analyzing ODS diagnosis result. Eventually our study secure availability of using ODS program at clinical training or developing diagnosis program. Subject of this study is 32 students participating in Sasang medical practice(12 subjects were So-Yang, 7 subjects were So-Eum, and 13 subjects were Tae-Eum). We analyze subject's clinical practice result reports by using ODS program and obtained result about pattern Identification. We used SPSS statistics 23 in analyzing the differences of the scores of Eight Principle Pattern Identification, Qi-Blood Pattern Identification, Bing-xie Pattern Identification, and Visceral Pattern Identification in each Sasang types (So-Yang, So-Eum, Tae-Eum). In the case of Heat-moisture, Tae-Eum showed higher score than So-Eum, but So-Yang showed no difference from the other two Sasang types(p<0.05). And in the case of Food-accumulation, Tae-Eum and So-Yang showed significantly higher score than So-Eum(p<0.05). It is hard to generalize the result because subject of this study was not enough. However, we explained correlation between pattern Identification in korean medicine and each sasang types based on quantifiable and objective evidence system. Therefore use of ODS program in student clinical practice training help to understand the relationship and correlation between different pattern Identification and will help standardization of clinical practice education.

• 한국안전학회지
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• 제25권3호
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• pp.7-14
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• 2010

In order to analyze the vibro-impacts in the torsional system, several clearance types of nonlinearities should be included with the analytical or numerical method. These kinds of nonlinear factors can cause the errors while the system is calculated specifically with the numerical method, also it might take too long to get right answers with the every nonlinearity in the original system. Therefore, there are several methods developed for the sake of overcoming the deficiency of the analysis with the original system and saving the calculating time. The original system can be reduced by keeping the system characteristics such as from 14 to 6 DOF. Especially, since the torque flow in the torsional system is connected with the specific gear ratios, the original system can be transferred into the simpler system corresponding to each gear ratio rather than the original system, which can also show the same system characteristics such as the natural frequencies and the mode shapes. By using the reduced system, the calculating time can be saved and the redundant nonlinear effects for the system analysis can be ignored without any numerical errors.

• 제어로봇시스템학회논문지
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• 제22권10호
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• pp.859-868
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• 2016

This paper proposes a new global positioning system (GPS) receiver algorithm to improve the positioning accuracy of a transporter using fault detection and isolation techniques from satellite signals. To improve the positioning accuracy, several factors including a feasible number of satellite signals, SNR, NAV Measurement Quality Indicator (mesQI), and Doppler, among others, have been utilized in the proposed algorithm. To increase the number of feasible satellite signals, an erroneous satellite signal has been replaced by the previous one. In conventional approaches, received GPS signals are analyzed and directly determined to be contaminated or not. The only clean signals are utilized for identifying the current location. This fault detection and isolation (FDI) feasibility test is popular for commercial GPS receivers. In the urban environment, especially near a building, the feasible number of satellite signals becomes insufficient to position the transporter. To overcome this problem, satellite signals are efficiently selected and recovered. Additionally, using the proposed GPS receiver algorithm, a feasible number of satellite signals can be increased, thereby improving the positional accuracy. Real world experiments using a transporter that carries blocks in a shipyard have demonstrated the superiority of the proposed algorithm compared to conventional approaches.

• 대한환경공학회지
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• 제39권4호
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• pp.194-200
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• 2017

현장형 조류수거시스템(이하 OACS)은 녹조 현상이 심각할 때 긴급 대책으로 투입되는 대안 중의 하나로, 대규모 수역에 투입되는 OACS가 갖추어야 할 조건은 신속대응성, 효율성 및 대용량이다. 부상분리 기술을 이용한 OACS의 성능은 부상 포집 수거 공정의 효율에 의해 결정되며, 처리용량 및 효율성에 가장 중요한 인자는 포집과 수거이다. 이들이 자동화되면 전체 작업속도와 일일 처리수량이 증가한다. OACS에 적용된 기술은 진보될수록 장비의 단순화 소형화와 포집과 수거 공정 자동화가 발전하여 신속대응성과 효율성이 향상되었으며, 잔류슬러지를 크게 줄여 친환경성과 수질 지속효과를 향상시켰고, 슬러지 수거량도 증가하여 대용량이 실현되는 방향으로 개선되었다. 그 결과 시스템은 조류증식비율을 극복할 수 있는 조류제거량을 달성할 수 있었고, 처리용량 대비 운영비가 감소되어 기술의 경제성을 크게 향상시켰다.

• 한국전자파학회논문지
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• 제28권1호
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• pp.76-79
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• 2017

본 논문에서는 저주파 자기유도방식의 소형 단말기 충전 기술에 적용되고 있는 상용 코일에 적용 가능한 연자성체 기반 차폐구조를 설계하였다. 연자성 재료는 높은 투자율과 낮은 자기손실 특성 등 강점이 있는데 반해, 낮은 절연 특성으로 와전류에 의한 전력 손실이 큰 단점이 있다. 본 연구에서는 연자성 재료에 격자형태의 패턴을 구현하여 와전류 경로를 줄임으로써 전력 손실을 개선하였으며, 외부로 누설되는 자기장 저감 효과를 가진 차폐구조를 제안하였다. Qi 표준인 WPC 상용 A10 코일을 위한 연자성체 기반 차폐구조를 설계하였으며, 제작 및 측정을 통해 본 논문에서 제안한 구조가 효과적으로 누설 자기장을 저감할 수 있음을 확인하였다.

• 한국항만경제학회지
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• 제31권1호
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• pp.171-188
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• 2015

물류시스템은 점점 더 중국의 경제성장을 위한 중요한 원동력 중 하나로 인정받고 있습니다. 물류효과의 폭이 넓어의 범위와 중국의 물류인프라, 물류산업의 발전과 함께 급속한 발전을 이루었습니다. 이 논문은 중국에서 2003년부터 2012년까지 기간 동안 31 지방을 포함하는 데이터 집합을 사용하여, 물류 발전과 경제 성장 사이의 관계를 조사합니다. 요인분석은 국가경제성장의 물류의 발전에 미치는 영향을 정의물류함수의 전체평가를 얻기 위해 적용됩니다. 고정효과패널 데이터의 접근방식에 따르면, 중국의 경제성장에 물류발전의 중요하고 긍정적인 영향은 그사이에, 해안지방과 내장 지방 사이 의 경제발전에 대한비교분석 도 실시, 발견된다. 결과는 경제성장에 물류발전의 영향은 서부지역에 비해 동부지역에서 높은 것이 좋습니다.

• 한국표면공학회지
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• 제43권5호
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• pp.238-242
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• 2010

In the present work, the influence of oxide on the Cr-Si-N coatings was investigated for the Cr-Si-O-N coatings on AISI 304 and Si wafer deposited by hybrid system, which combines the DC magnetron sputtering technique and arc ion plating (AIP) using Cr and Si target in an $Ar/N_2/O_2$ gaseous mixture. As the O content in the Cr-Si-N coatings increased, the diffraction patterns of the Cr-Si-O-N coatings showed CrN and $Cr_2O_3$ phases. However, as the O content increased to 28.8 at.%, diffraction peak of $Cr_2O_3$ was disappeared in the Cr-Si-O-N coating. The $d_{200}$ value was decreased with increasing of O content. The average grain size increased from about 40 nm to 65 nm as the O content increased. The maximum micro-hardness of the Cr-Si-O-N coating was obtained 4507 Hk at the O content of 24.8 at.%. The average friction coefficient of the Cr-Si-O-N coatings was gradually decreased by increasing the O content and the average friction coefficient decreased from 0.37 to 0.25 by increasing the O content. These results indicated that amorphous phase was increased in the Cr-Si-O-N coatings by increasing of O content.