• Journal of Broadcast Engineering
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• v.6 no.1
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• pp.21-31
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• 2001

In the PN-sequence based audio watermarking system, the PN sequence is shaped by a filter derived from the psychoacoustic model to increase robustness and inaudibility The psychoacoustic model calculated in each audio segment, however, requires heavy computational loads. In this paper, we propose an efficient watermarking system adopting a fixed-shape perceptual filter that substitutes psychoacoustic model derived filter. The proposed filter can shape the PN-sequence to be inaudible and enable to embed the robust watermark in a simple manner. Moreover, we propose an anchitecture for the PN-sequence compensation fitter In the watermark detecter to increase correlation between the watermark and the PN-sequence. With the proposed architecture, the blind watermark detection performance has been enhanced.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.145-150
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• 2010

In this paper, we propose additional data transmission system for spectrum efficiency improvement and derive channel capacity formula as a approximated closed-form. Spread spectrum watermarking scheme is selected for the watermarking embedder. Nakagami-q (Hoyt) model is considered as a multipath fading channel. Numerical results show the channel capacity variation of the proposed system in wireless fading channel. From the results, we confirm that the channel capacity of the watermarking system is affected by the fading coefficient and system parameters such that host sampling frequency, host-to-watermark ratio, watermark-to-noise ratio, and PN sequence length.

• The Journal of the Korea Contents Association
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• v.3 no.1
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• pp.21-30
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• 2003

Retracing schemes using packet marking are currently being studied to protect network resources by isolating DDoS attack. One promising solution is the probabilistic packet marking (PPM). However, PPM can't use ICMP by encoding a mark into the IP identification field. Likewise, it can't identify the original source through a hash function used to encode trace information and reduce the mark size. In addition, the retracing problem overlaps with the result from the XOR operation. An algorithm is therefore proposed to pursue the attacker's source efficiently. The source is marked in a packet using a router ID, with marking information abstracted.

• Proceedings of the Technology Innovation Conference
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• 2005.08a
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• pp.113-137
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• 2005

본 연구는 각 프로세스가 조직에 미치는 상대적 영향을 고려한 조직 전체의 효율성을 평가하고, 조직의 효율성을 개선하기 위하여 조직을 구성하는 여러 프로세스 중에서 어떤 프로세스를 우선적으로 개선해야 하는지를 결정하며, 더 나아가 비효율적인 프로세스를 개선하기 위하여 어떤 프로세스를 벤치마킹해야 하는지를 결정할 수 있는 체계적인 방법을 제공한다. 이를 위하여 본 연구는 다음과 같은 중요한 세 가지 과정을 따른다. 첫째, DEA(data envelopment analysis)의 CCR 모형을 이용하여 프로세스의 투입요소와 산출 요소를 바탕으로 개별 프로세스의 효율성을 평가한다. 둘째, 도출된 개별프로세스의 효율성을 Lovell과 Pastor의 순수 산출요소(또는 투입요소) DEA 모형의 산출요소로 이용하여 서비스 단위 조직 전체의 효율성을 평가한다. 셋째, 앞서 도출된 개별프로세스의 효율성과 서비스 단위 조직의 전체 효율성을 각각 DT(decision tree)의 예측변수와 목표변수로 활용하여 각 서비스 단위 조직의 특성 및 상황에 따라 개선해야 할 프로세스를 선택하는 규칙을 생성한다. 제안한 방법을 통하여 기업은 비효율적 조직과 프로세스를 발견하고 조직의 효율성을 개선하기 위하여 어떤 프로세스를 우선적으로 개선해야 하는지를 결정할 수 있다. 이를 통하여 기업은 오늘날 기업 경쟁력의 핵심인 프로세스를 좀 더 효과적으로 평가 및 관리할 수 있을 것으로 기대된다.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.84-94
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• 2021

Graph databases have been developed to efficiently store and query graph data composed of vertices and edges to express relationships between objects. Since the query types of graph database show very different characteristics from traditional NoSQL databases, benchmarking tools suitable for graph databases to verify the performance of the graph database are needed. In this paper, we propose an efficient graph database benchmarking system that supports diversity in graph inputs and queries. The proposed system utilizes OrientDB to conduct benchmarking for graph databases. In order to support the diversity of input graphs and query graphs, we use LDBC that is an existing graph data generation tool. We demonstrate the feasibility and effectiveness of the proposed scheme through analysis of benchmarking results. As a result of performance evaluation, it has been shown that the proposed system can generate customizable synthetic graph data, and benchmarking can be performed based on the generated graph data.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.213-230
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• 2020

Until now, various educational budgets, facilities, and programs have been put into school education, but the results have not been clearly evaluated. This study presents a model to analyze the effectiveness of educational support for students in high schools across the country. In this model, we first use EM cluster analysis to make clusters with similar inputs for school operation, and then calculate the relative efficiency in each cluster by using Network DEA analysis. The Network DEA analysis has a two-stage structure where the first stage uses six inputs in terms of school infrastructure to generate outputs such as the number of academic persistence. In the Network DEA analysis, the second stage uses 10 inputs in terms of school programs to generate outputs such as the number of enrollees to higher learning and the number of employees and per capita usage of library as the connection variable. Based on the efficiency analysis results, Tier analysis is performed by applying the Euclidean distance to select targets for benchmarking. In this study, we applied the model to analyze the efficiency of educational support by collecting data regarding student education support in general and vocational high school nationwide. The stepwise benchmarking method proposed that the target be selected for efficiency improvement step by step, taking into account inefficient school elements to complement the problem of the choice of benchmarking targets. Based on this study, it is expected that schools with low efficiency of educational support for students will be used as basic data for stepwise benchmarking for efficient operation of educational support for students.

• Journal of Korea Port Economic Association
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• v.25 no.1
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• pp.15-28
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• 2009

The purpose of this paper is to show the empirical extraction way of benchmarking ports for overcoming the shortcoming which the traditional DEA method has by using 20 Korean ports in 2003 for 2 inputs (birthing capacity, cargo handling capacity) and 2 outputs(Export and Import Quantity, Number of Ship Calls). Because DEA method has produced the limited set of efficient units which are reference to inefficient units respective of their differences in efficiency scores, it is necessary to adopt the more feasible benchmarking information according to the path analysis(tier or stratification). The core empirical results of this paper are as follows. Benchmarking ports against inefficient ports according to the tier analysis are that Masan Port(Janghang$\rightarrow$Jeju$\rightarrow$Seogoipo$\rightarrow$Yeosu), Jinhae Port(Janghang$\rightarrow$Mogpo$\rightarrow$Seogoipo$\rightarrow$Wando), Pohang&DonghaePort(Janghang$\rightarrow$Samcheonpo$\rightarrow$Pyungtag$\rightarrow$Samcheog), and Sogcho Port(Janghang$\rightarrow$Mogpo$\rightarrow$Seogoipo$\rightarrow$Wando). The policy implication to the Korean seaports and planners is that Korean seaports should introduce the new methods like Tier analysis of this paper for evaluating the port performance and enhancing the efficiency in short term, mid term, and long term according to the tier 3 stage, the tier 2 stage, and the tier 1 stage with original DEA stage.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.217-220
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• 2001

본 논문에서는 MPEG 비트스트림 기반의 동영상 저작권 보호를 위한 간단하면서도 효율적인 실시간 워터마킹 알고리즘을 제안한다. 제안된 알고리즘에서는 MPEG 부호화된 동영상에 대해 DCT 계수 영역으로 부분 복호화한 후 양자화 기법을 사용하여 DC 계수에 비가시성을 가지도록 워터마크를 삽입한다. 실험결과 제안된 알고리즘은 기존의 비트스트림 기반 워터마킹 기법보다 계산 복잡도 및 강인성 면에서 향상된 성능을 보여주고 있다.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.274-279
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• 2006

대부분의 컬러 영상들은 코드북의 일부분만으로 표현할 수 있는 영상의 영역이 상당히 크므로 이러한 특징을 이용하는 효율적인 Reversible 워터마킹 기법을 제안한다. 팔레트(컬러맵) 영상에서의 워터마킹 기술에 대한 연구는 많이 있지만 Reversibility에 대한 관심은 상대적으로 낮았다. 제안하는 기법은 가상적으로 확장한 코드북에 의한 압축 영역에서 동작한다. 확장된 코드북은 높은 Payload 용량을 가진다. Reversibility를 구현하면서 왜곡(Distortion)과 삽입용량(Embedding capacity)사이의 절충점을 실험을 통해 보인다.

• Review of KIISC
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• v.12 no.1
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• pp.19-24
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• 2002

시간 영역에서 수행하는 대역확산 워터마킹의 경우 들리지 않으면서도 강인한 워터마크를 생성하기 위해 심리음향 모델을 이용한다. 주파수 영역에서 심리음향모델에 의해 변형된 PN 시퀸스는 시간 영역으로 역변환되어 원신호에 삽입된다. 워터마크가 삽입된 오디오 신호가 WEG 오디오 부호화 과정을 통과할 경우, 다시 심리음향모델과 주파수 변환을 수행하는 중복 연산이 요구된다. 본 논문에서는 WEG오디오 부호화 과정과 오디오 워터마킹 과정을 결합시킴으로써 중복 연산을 피한 효율적인 오디오 워터마킹 알고리즘을 제안한다. 제안된 알고리즘은 MPEG 오디오 부호화 중에서, 특히, MP3 부호화 과정에 대해 수행하였으며, MDCT 영역에서 워터마크를 삽입한다. 삽입된 워터마크 신호는 일반적인 대역확산 워터마킹 복호화기를 이용하여 시간 영역에서 검출이 가능하며, 기존의 방법과 유사한 수준의 복호화 성능을 나타낸다.