• The Journal of the Acoustical Society of Korea
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• v.24 no.2E
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• pp.67-70
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• 2005

To realize a traditional music recognition system, some characteristics pertinent to Far East Asian music should be found. Using Spectrogram, some distinct attributes of Korean traditional music are surveyed. Frequency distribution, beat cycle and frequency energy intensity within samples have distinct characteristics of their own. Experiment is done for pre-experimentation to realize Korean traditional music recognition system. Using characteristics of Korean traditional music, $94.5\%$ of classification accuracy is acquired. As Korea, Japan and China have the same musical roots, both in instruments and playing style, analyzing Korean traditional music can be helpful in the understanding of Far East Asian traditional music.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.448-450
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• 2004

센서 네트워크는 다양한 탐지 대상 및 환경을 감시하는데 유용하게 사용될 수 있다 이러한 센서 네트워크에서 센서 노드간 키를 설립하는 것은 보안을 위한 가장 기본적인 요구 사항이다 하지만 센서가 가진 기본 특성인 자원의 제약 때문에 일반 네트워크에서 사용되고 있는 중앙 키 분배 서버를 이용한 키 분배나 공개키 기법을 사용하는 것은 적합하지 않다. 따라서 본 논문에서는 센서 네트워크 특성에 맞는 키의 사전 분배 방식을 제안한다. 본 논문에서 제시한 기법은 클러스터를 기반으로 위치 정보를 이용하여 키를 사전 분배하였기 때문 에 노드간 키 설립확률을 높였을 뿐만 아니라, 악의적인 노드에 의해 다항식이 공개되어 정상 노드가 붕괴되는 것을 막기 위해 클러스터당 헤드를 두어 다항식을 공유하는 노드의 범위를 줄여 보안을 보다 강화 시켰다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.445-447
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• 2004

네트워크 단위로 이동성을 제공하는 네트워크 이동성(NEtwork Mobility, NEMO)프로토콜에서 방문 네트워크(Visited Network)는 이동네트워크의 홈 네트워크(Home Network)를 통해 이동 네트워크(Mobile Network)를 인증한다. 안전한 인증이 이루어지기 위해서 홈 네트워크의 인증 서버와 이동 네트워크간의 사용할 키가 필요하게 된다. 그러나 두 엔터티간 키 협정을 위해 메시지를 주고받는 것은 서비스 에러나 공격에 취약하고 대역폭이나 밧데리 등이 제한적인 무선 환경에서는 적절하지 않다. 많은 키 결정 알고리즘에서 사용되는 공개 키 기반 알고리즘은 이런 무선 환경에 적절하지 않다. 또한 비밀키 선분배 방식은 인증 서버가 자신이 인증해야할 모든 노드와의 키 쌍을 가지고 있어야 한다는 정에서 확장성 문제를 지닌다. 이런 문제를 해결하기 위해, 본 논문에서는 회귀분석을 이용하여 쉽게 노드가 가지고 있는 키를 계산하고, 비밀키 인증서를 이용하여 간편하고 빠르게 인증을 수행할 수 있는 새로운 키 선분배 및 인증 메커니즘을 제안한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.160-160
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• 2008

In practical etching process, etch ant is sprayed on the metal-deposited panel through nozzles collectively connected to the manifold and that panel is usually composed of many PCB(printed circuit board)'s. The etching uniformity, the difference between individual PCB's on the same panel, has become one of most important features of etching process. In this paper, the prediction of nozzle trajectory has been performed by the combination of algebraic formula and numerical simulation. With the pre-determined geometrical factors of nozzle distribution, the trajectories of individual nozzles were predicted with the change of process operational factors such as panel speed, nozzle swing frequency and so on. As results, two dimensional distribution of impulsive force of etchant spray which could be considered as a key factor determining the etching performance have been successfully obtained. Though only qualitative prediction of etching uniformity have been predicted by the process developed in this study, the expansion to the quantitative prediction of etching uniformity is expected to be apparent by this study.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.32-40
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• 2006

It is very important to establish a pairwise key securely in wireless sensor networks. Because sensor networks consist of devices with weak physical security, they are likely to be compromised by an attacker. However, some approaches using key pre-distribution and other approaches using one hop local keys are known to be very vulnerable to threats caused by compromised nodes, even a small number. This paper proposes a scheme where each node establishes three hop local keys and employs them for a later pairwise key establishment. When any two nodes agree a pairwise key, all nodes on the route between two nodes contribute to the agreement of the pairwise key. Here, the initial three hop local keys are employed for encrypting a secret key delivered from a node to other nodes. Therefore, the proposed scheme bothers attackers to compromise much more nodes than the scheme using one hop local keys only. The simulation results have proven that the proposed scheme provides better performance and higher security than the scheme using one hop local keys in terms of message exchange, the number of encryption and decryption, and pairwise key exposure rate.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.527-533
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• 2017

Environmental concern about smart phone is growing because it has short product life span while having intensive production technology and cost. In this study environmental impact of the smart phone is quantified using the LCA methodology based on the ISO 14040 series standards. The assessment considers potential environmental impacts across the whole life cycle of the smart phone including; pre-manufacturing; manufacturing; distribution; product use; and end-of-life stages. The pre-manufacturing stage is the most dominant life cycle stage causing the highest environmental impacts among all 10 impact categories assessed. The global warming impacts of the smart phone in the pre-manufacturing, distribution, use, manufacturing, and end-of-life stages were 52.6% 23.9%, 15.7%, 7.0%, and 0.8%, respectively. Sensitivity of the life cycle impact assessment results to the system boundary definition and assumptions made were quite high. Three components of the smart phone, PCB, battery, and display module were identified as the key components causing majority of the potential environmental impact in the pre-manufacturing stage. As such the slim and light-weight design and the use of environmental friendly materials are important design factors for reducing the environmental impact of the smart phone.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.616-619
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• 2008

In this paper, we design and implement the authentication system for home network service and applied it to actual sensor nodes. We achieved authentication key, encryption and decryption applied RC5 encryption algorithm of SNEP. In addition, we used pair-wise key pre-distribution for prevention of authentication sniffing in wireless sensor network. The experiment environment consists of a base station receiving data and sensor nodes sending data. Each sensor nodes sends both the data and encrypted authentication key to the base station. As a simulation environment, we assumed some what-if scenarios of security menaces in home network service. And we slightly altered the TOS_Msg construction of TinyOS. The experiences had shown that the malfunction doesn't happen in communication among other groups. And we confirmed in tests that the system is secure when a sensor having malicious propose is added.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.553-558
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• 2007

In this paper, we introduce a set of structures and algorithms for communication efficient public key revocation in wireless sensor networks. Unlike the traditional networks, wireless sensor network is subjected to resources constraints. Thus, traditional public key revocation mechanisms such like the ordinary certificate revocation list is unsuitable to be used. This unsuitability is due to the huge size of required representation space for the different keys' identifiers and the revocation communication as the set of revoked keys grow. In this work, we introduce two communication-efficient schemes for the certificate revocation. In the first scheme, we utilize the complete subtree mechanism for the identifiers representation which is widely used in the broadcast encryption/user revocation. In the second scheme, we introduce a novel bit vector representation BVS which uses vector of relative identifiers occurrence representation. We introduce different revocation policies and present corresponding modifications of our scheme. Finally, we show how the encoding could reduce the communication overhead as well. Simulation results and comparisons are provided to show the value of our work.

• Steel and Composite Structures
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• v.46 no.6
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• pp.773-791
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• 2023

Connections with damage concentrated to pre-selected components can enhance seismic resilience for moment resisting frames. These pre-selected components always yield early to dissipate energy, and their energy dissipation mechanisms vary from one to another, depending on their position in the connection, geometry configuration details, and mechanical characteristics. This paper presents behaviour insights on two types of beam-to-beam connections that the angles were designed as energy dissipation components, through the results of experimental study and finite element analysis. Firstly, an experimental programme was reviewed, and key responses concerning the working mechanism of the connections were presented, including strain distribution at the critical section, section force responses of essential components, and initial stiffness of test specimens. Subsequently, finite element models of three specimens were established to further interpret their behaviour and response that were not observable in the tests. The moment and shear force transfer paths of the composite connections were clarified through the test results and finite element analysis. It was observed that the bending moment is mainly resisted by axial forces from the components, and the dominant axial force is from the bottom angles; the shear force at the critical section is primarily taken by the slab and the components near the top flange. Lastly, based on the insights on the load transfer path of the composite connections, preliminary design recommendations are proposed. In particular, a resistance requirement, quantified by a moment capacity ratio, was placed on the connections. Design models and equations were also developed for predicting the yield moment resistance and the shear resistance of the connections. A flexible beam model was proposed to quantify the shear resistance of essential components.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.72-81
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• 2009

This paper provides simulational round robin test results for welding residual stress prediction of safety/relief nozzle. To quantify the welding variables and define the recommendation for prediction and determination of welding residual stress, 6 partners in 5 institutes participated in round robin test. It is concluded that compressive axial and hoop residual stress occurs in dissimilar metal weld and pre-existing residual stress distribution in dissimilar metal weld was affected by similar metal weld due to short length of safe end. Although the reason for the deviation among the results was not pursued further, the effect of several key elements of FE analyses on welding residual stress was investigated in this paper.