• Journal of Energy Engineering
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• v.4 no.1
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• pp.13-22
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• 1995

공정산업에서 열교환망의 최적화를 통한 에너지 회수 및 절감 기술의 개발을 목적으로, 여러 개의 핀치를 갖거나 또는 안전 및 배열 등과 같은 제약조건들이 주어진 계를 대상으로, 계의 분리법(system separation method)을 적용하여 신뢰도가 높은 목표값(target)을 설정하는 연구의 일환이다. 본 연구에서는 그 목표값의 10% 이내에 도달할 수 있도록 실제적인 열교환망 합성을 수행하는 프로그램 개발에 중점을 두었으며, 조업 중인 기존 공정에 적용해 본 결과, 연간 총비용의 15% 정도를 절감할 수 있는 결과를 얻을 수가 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.613-631
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• 2013

Cognitive radio (CR) is proposed as a key solution to improve spectral efficiency and overcome the spectrum scarcity. Spectrum sensing is an important task in each CR system with the aim of identifying the spectrum holes and using them for secondary user's (SU) communications. Several conventional methods for spectrum sensing have been proposed such as energy detection, matched filter detection, etc. However, the main limitation of these classical methods is that the CR network is not able to communicate with its own base station during the spectrum sensing period and thus a fraction of the available primary frame cannot be exploited for data transmission. The other limitation in conventional methods is that the SU data frames should be synchronized with the primary network data frames. To overcome the above limitations, here, we propose a spectrum sensing technique based on blind source separation (BSS) that does not need time synchronization between the primary network and the CR. Moreover, by using the proposed technique, the SU can maintain its transmission with the base station even during spectrum sensing and thus higher rates are achieved by the CR network. Simulation results indicate that the proposed method outperforms the accuracy of conventional BSS-based spectrum sensing techniques.

• ETRI Journal
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• v.43 no.4
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• pp.702-716
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• 2021

This work proposes suitable network configurations for single frequency networks (SFNs) with ATSC 1.0 based on network coverage calculations and the laboratory multipath handling performance of commercial receivers. SFNs are widely used for delivering terrestrial digital television services because of their efficient use of the spectrum. In Mexico the analogue television transmissions switch-off occurred on 31 December 2016. Thus it is expected the adopted ATSC 1.0 system will be in force for the next several years despite the recent standardization of the ATSC 3.0 system. As ATSC 1.0 uses 8-VSB modulation the multipath handling capability of receivers is critical for the design of SFNs. The presented network planning results help develop technical normativity for implementing SFNs in Mexico and other countries that use ATSC 1.0. SFNs with transmitter separation up to 130 km are fully covered for outdoor reception mainly due to the directivity of the receiving antenna. Moreover for indoor reception at least 70% of an SFN coverage area can be achieved with a transmitter separation of up to 60 km depending on the radiated power and the transmitter antenna height.

• Journal of Korea Multimedia Society
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• v.21 no.2
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• pp.77-86
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• 2018

Although separation of touching pigs in real-time is an important issue for a 24-h pig monitoring system, it is challenging to separate accurately the touching pigs in a crowded pig room. In this study, we propose a separation method for touching pigs using the information generated from Convolutional Neural Network(CNN). Especially, we apply one of the CNN-based object detection methods(i.e., You Look Only Once, YOLO) to solve the touching objects separation problem in an active manner. First, we evaluate and select the bounding boxes generated from YOLO, and then separate touching pigs by analyzing the relations between the selected bounding boxes. Our experimental results show that the proposed method is more effective than widely-used methods for separating touching pigs, in terms of both accuracy and execution time.

• Proceedings of the SAREK Conference
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• 2004.11a
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• pp.59-59
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• 2004

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.37-44
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• 2020

Due to the recent COVID 19 pandemic, public institutions are increasingly working from home. Working in public institutions is rapidly changing into a smart work environment where time and space constraints disappear. However, many public institutions currently lack a security model for an efficient smart work environment due to the physical network separation system that separates the Internet network and the business network. Therefore, in this paper, we describe the current limitations for implementing smart work in a physical network separation environment of public institutions, and propose a security model necessary for a work environment to supplement them. As a related study, explain SSL VPN and explain smart work business model through security model research of SDP (Software Defined Perimeter), RDP (Remote Desktop Protocol), and VDI (Virtual Desktop Infrastructure) to overcome the security limitations of SSL VPN. As a result, we intend to propose a security model for a smart work environment suitable for public institutions while complying with the physical network separation security guide.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.580-599
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• 2021

Software-Defined Networking (SDN) has three key features: separation of control and forwarding, centralized control, and network programmability. While improving network management flexibility, SDN has many security issues. This paper systemizes the security threats of SDN using spoofing, tampering, repudiation, information disclosure, denial of service, and elevation of privilege (STRIDE) model to understand the current security status of SDN. First, we introduce the network architecture and data flow of SDN. Second, we analyze security threats of the six types given in the STRIDE model, aiming to reveal the vulnerability mechanisms and assess the attack surface. Then, we briefly describe the corresponding defense technologies. Finally, we summarize the work of this paper and discuss the trends of SDN security research.

• Atmosphere
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• v.20 no.3
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• pp.343-353
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• 2010

A regional wind network with complex surface conditions must be designed with sufficient space and time resolution to resolve the local circulations. In this study, the spatial variations of the wind field observed in the Seoul and Jeju regional networks were evaluated in terms of annual, seasons, and months to assess the spatial homogeneity of wind fields within the regional networks. The coherency of the wind field as a function of separation distance between stations indicated that significant coherency was sometimes not captured by the network, as inferred by low correlations between adjacent stations. A meso-velocity scale was defined in terms of the spatial variability of the wind within the network. This problem is predictably most significant with weak winds, dull prevailing wind, clear skies and significant topography. The relatively small correlations between stations imply that the wind at a given point cannot be estimated by interpolating winds from the nearest stations. For the Seoul and Jeju regional network, the meso-velocity scale has typically a same order of magnitude as the speed of the network averaged wind, revealing the large spatial variability of the Jeju network station imply topography and weather. Significant scatter in the relationship between spatial variability of the wind field and the wind speed is thought to be related to thermally-generated flows. The magnitude of the mesovelocity scale was significantly different along separation distance between stations, wind speed, intensity of prevailing wind, clear and cloudy conditions, topography. Resultant wind vectors indicate much different flow patterns along condition of contributing factors. As a result, the careful considerations on contributing factors such as prevailing wind in season, weather, and complex surface conditions with topography and land/sea contrast are required to assess the spatial variations of wind field on a regional network. The results in the spatial variation from the mesovelocity scale are useful to represent the characteristics of regional wind speed including lower surface conditions over the grid scale of large scale atmospheric model.

• Convergence Security Journal
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• v.23 no.1
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• pp.9-17
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• 2023

Due to COVID-19, the concept of Zero Trust, a safe security in a non-face-to-face environment due to telecomm uting, is drawing attention. U.S. President Biden emphasized the introduction of Zero Trust in an executive order to improve national cybersecurity in May 2021, and Zero Trust is a global trend. However, the most difficulty in introd ucing new technologies such as Zero Trust in Korea is excessive regulation of cloud and network separation, which is based on the boundary security model, but is limited to not reflecting all new information protection controls due to non-face-to-face environments. In particular, in order for the government's policy to ease network separation to b ecome an effective policy, the zero trust name culture is essential. Therefore, this paper aims to study legal improve ments that reflect the concept of zero trust under the Electronic Financial Transactions Act.

• Journal of Communications and Networks
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• v.13 no.6
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• pp.612-620
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• 2011

Recently, one of the problems with the Internet is the issue of scalability. To this end, locator/identifier separation protocol (LISP), which separates end-system identifiers and routing locators, has been proposed as a solution. In the LISP deployed network, the ingress and egress nodes of inter-AS traffic is determined by edge router selection (ERS) and endpoint identifier-routing locator mapping assignment (ERMA). In this paper, joint optimizations of ERS and ERMA for stub networks with and without predetermined link weights are studied and the mixed integer linear programming (MILP) formulations for the problems are given. To make the problem with optimizable link weights tractable, a revised local search algorithm is also proposed. Simulation results show that joint optimization of ERS and ERMA enables better network performance.