• 한국경영과학회지
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• 제36권4호
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• pp.29-41
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• 2011

As industires are evolving into a more advanced type industrial system, service economy has been more emphasized. But with the expansion of the service economy, the failure of the service has also increased. Customers flee caused by the service failure leads to from simple problems like financial loss to serious problems like damaging corporate image. Therefore, if possible, the system providing defect-free service should be established. If this is not possible, preventive measures should be taken in order to minimize the failure. The study as a tool to prevent service failure presents the concepts "service error matrix." And to confirm whether this idea is practical or not, this study investigated the hotel, one of the leading service industries, about actually occurring service failure and applied to service error matrix suggested in this study. Finally service blueprint and Poka-yoke are completed in order to reduce service failure of Y hotel which was the object of the interview for this study.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.73-78
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• 2015

Touch panel is mainly applied to pressure type touch panel but it occur a low recognition rate and error during long-term use. So, it is partly applied to capacitive touch panel to compensate for these problems but it also can occur a same problems via pollutions. Touch technology has developed a various method but it is not used because of high costs and difficult installation process. So, in this paper, we proposed an input method of touchless panel using IrDA matrix. This method is conducted using an IrDA Matrix composed of depth sensor. It is possible to offer a various contents for multi user. The proposed technology need a development of a high sensitivity sensing method and high-speed processing method of position information for Seamless operation control. And, it is required high-precision drive technology. Also, we proposed a Seamless user recognition for interactive contents service through a touchless panel using IrDA matrix.

• 한국산업융합학회 논문집
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• 제27권2_2호
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• pp.343-356
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• 2024

Super app is an application that provides a variety of services in a unified interface within a single platform. With the acceleration of digital transformation, super apps are becoming more prevalent. This study aims to suggest service enhancement measures by analyzing the user review data before and after the transition to a super app. To this end, user review data from a payment-based super app(Shinhan Play) were collected and studied via topic modeling. Moreover, a matrix for assessing the importance and usefulness of topics is introduced, which relies on the eigenvector centrality of the inter-topic network obtained through topic modeling and the number of review recommendations. This allowed us to identify and categorize topics with high utility and impact. Prior to the transition, the factors contributing to user satisfaction included 'payment service,' 'additional service,' and 'improvement.' Following the transition, user satisfaction was associated with 'payment service' and 'integrated UX.' Conversely, dissatisfaction factors before the transition encompassed issues related to 'signup/installation,' 'payment error/response,' 'security authentication,' and 'security error.' Following the transition, user dissatisfaction arose from concerns regarding 'update/error response' and 'UX/UI.' The research results are expected to be used as a basis for establishing strategies to strengthen service competitiveness by making super app services more user-oriented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.343-364
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• 2021

In the 5G era, the communication networks tend to be ultra-densified, which will improve the accuracy of indoor positioning and further improve the quality of positioning service. In this study, we propose an indoor three-dimensional (3D) dynamic reconstruction fingerprint matching algorithm (DSR-FP) in a 5G ultra-dense network. The first step of the algorithm is to construct a local fingerprint matrix having low-rank characteristics using partial fingerprint data, and then reconstruct the local matrix as a complete fingerprint library using the FPCA reconstruction algorithm. In the second step of the algorithm, a dynamic base station matching strategy is used to screen out the best quality service base stations and multiple sub-optimal service base stations. Then, the fingerprints of the other base station numbers are eliminated from the fingerprint database to simplify the fingerprint database. Finally, the 3D estimated coordinates of the point to be located are obtained through the K-nearest neighbor matching algorithm. The analysis of the simulation results demonstrates that the average relative error between the reconstructed fingerprint database by the DSR-FP algorithm and the original fingerprint database is 1.21%, indicating that the accuracy of the reconstruction fingerprint database is high, and the influence of the location error can be ignored. The positioning error of the DSR-FP algorithm is less than 0.31 m. Furthermore, at the same signal-to-noise ratio, the positioning error of the DSR-FP algorithm is lesser than that of the traditional fingerprint matching algorithm, while its positioning accuracy is higher.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.3057-3075
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• 2020

End-to-end network delay plays an vital role in distributed services. This delay is used to measure QoS (Quality-of-Service). It would be beneficial to know all node-pair delay information, but unfortunately it is not feasible in practice because the use of active probing will cause a quadratic growth in overhead. Alternatively, using the measured network delay to estimate the unknown network delay is an economical method. In this paper, we adopt the state-of-the-art matrix completion technology to better estimate the network delay from limited measurements. Although the number of measurements required for an exact matrix completion is theoretically bounded, it is practically less helpful. Therefore, we propose an online adaptive sampling algorithm to measure network delay in which statistical leverage scores are used to select potential matrix elements. The basic principle behind is to sample the elements with larger leverage scores to keep the traits of important rows or columns in the matrix. The amount of samples is adaptively decided by a proposed stopping condition. Simulation results based on real delay matrix show that compared with the traditional sampling algorithm, our proposed sampling algorithm can provide better performance (smaller estimation error and less convergence pressure) at a lower cost (fewer samples and shorter processing time).

• 한국전자통신학회논문지
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• 제11권5호
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• pp.459-464
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• 2016

이동통신서비스가 넓게 확대되고, 서비스영역의 확대로 인해 중계기가 급속히 증가하고 있다. 이동통신 서비스의 큰 서비스 구역으로 간섭제거시스템을 위한 새로운 Signed CMA알고리즘을 제안한다. 제안된 Signed CMA알고리즘은 조정된 스텝사이즈 값에 의해 성능이 개선된다. 우리는 Signed CMA의 평균자승에러를 개선한다. 매트랩은 실험결과에 맞춰 제안된 알고리즘과 비교 분석하여 사용한다. 수렴횟수 1000번일 때 스텝사이즈 0.0065를 가진 제안된 Signed CMA알고리즘의 최소자승에러 성능이 기존 CMA 알고리즘보다 약 5 dB 더 낫다.

• 한국컴퓨터정보학회논문지
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• 제25권9호
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• pp.143-150
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• 2020

본 연구는 다중위해사례를 중심으로 경호임무수행 간 출입통제 활동을 실시하는 과정에서 유발되는 경호원의 휴먼에러가 무엇인지 규명하고 그에 따른 대책을 제시하는데 목적이 있다. 이를 검증하고자 사건의 순서를 시계열로 배열한 뒤 변동노드를 중심으로 문제점을 파악할 수 있는 'VTA 기법'과 'Why-Why 분석 기법'을 활용하였으며, 추가적으로 'M-SHEL Matrix'를 통하여 휴먼에러를 유발하는 환경요인과 개인요인을 추출하였다. 분석결과, 출입통제 사고를 유발하는 경호환경요인으로는 시간부족(조급함), 방문자에 대한 편견, 편중된 근무방법, 보안 관리미흡, 무사안일주의, 익숙한 분위기(긴장이완), 형식적인 근무활동, 편의제공, 과소평가 등으로 조사되었다. 그리고 경호원 개인적 측면에서 유발되는 휴먼에러는 낮은 경계의식, 형식적인 근무, 검측소홀, 안일한 대처 등으로 조사되었다.

• 한국항해항만학회지
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• 제38권2호
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• pp.121-126
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• 2014

본 논문은 저가형 GPS 수신 모듈에 DGPS 서비스를 적용하기 위한 방안으로 NMEA GPGSV 데이터의 위성 배치 정보에 포함된 위성 앙각과 방위각으로 관측 행렬을 구성한 후, 거리기반 보정정보를 위치영역으로 투영하여 기 산출된 위치 오차 벡터를 수정하는 방안을 제시하였다. 저가형 수신기인 U-blox LEA-5H 모델의 출력 데이터에 제안한 알고리즘을 적용한 결과 주 활동 시간인 낮 시간에 수평 오차 RMS를 1.8m에서 1m 이내로 줄였으며, 수직 정확도는 RMS 5.8m에서 1.4m로 75% 향상시킴을 확인하였다. 본 논문에서 제안하는 방식은 하드웨어의 변경없이 소프트웨어만으로 저가형 GPS의 성능을 DGPS 수준으로 향상시키는 기법이므로, 소비자와 제조사의 부담을 경감시켜 향후 제공될 고정밀 측위 서비스 인프라의 활성화에 기여할 수 있을 것으로 기대된다.

• International Journal of Contents
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• 제14권1호
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• pp.39-44
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• 2018

Today, cars have developed into intelligent automobiles that combine advanced control equipment and IT technology to provide driving assistance and convenience to users. These vehicles provide infotainment services to the driver, but this does not improve the safety of the driver. Accordingly, V2X communication, which forms a network between a vehicle and a vehicle, between a vehicle and an infrastructure, or between a vehicle and a human, is drawing attention. Therefore, various techniques for improving channel estimation performance without changing the IEEE 802.11p standard have been proposed, but they do not satisfy the packet error rate (PER) performance required by the C-ITS service. In this paper, we analyze existing channel estimation techniques and propose a new channel estimation scheme that achieves better performance than existing techniques. It does this by applying the updated matrix for the data pilot symbol to the construct data pilot (CDP) channel estimation scheme and by further performing the interpolation process in the frequency domain. Finally, through simulations based on the IEEE 802.11p standard, we confirmed the performance of the existing channel estimation schemes and the proposed channel estimation scheme by coded PER.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4584-4599
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• 2021

In IEEE 802.11p-based wireless access in vehicular environments (WAVE) communication systems, channel estimation (CE) is one of the important issues to provide stable communication service. It is hard to apply conventional CE schemes based on data pilot to real systems, because error propagation occurs in high mobility and modulation order environments, resulting in degrading the CE performance. In this paper, we propose one data pilot using multiple receive antennas (ODPM) CE scheme based on the weighted sum using update matrix (WSUM) with time-domain averaging (TDA) to overcome this problem. Within the process of WSUM-TDA in the proposed scheme, the maximum ratio combining (MRC) technique is applied so as to create more accurate one data pilot. Moreover, a new reliability test criterion is proposed as the fashion of utilizing MRC, which makes it possible to apply selective TDA that guarantees performance improvement. In simulation results, the packet error rate (PER) performance of the proposed ODPM is compared with that of conventional CE methods and its superiority is demonstrated.