발전소 순환수계통 수직펌프의 진동저감에 관한 연구

박혁,유호선,Park, Hyeok,Yoo, Ho-Seon 한국플랜트학회 2013 플랜트 저널 Vol.9 No.1

본 연구에서는 국내 P복합발전소에서 실제 운전 중인 순환수계통 수직펌프를 대상으로 고유진동수를 측정하고, 유체와 구조가 연성된 경우의 진동이론으로부터 고진동의 원인을 파악하였다. 현장 상황에 가장 적합하며 경제적인 공진방지 대책을 선정하여 수치해석을 통해 실효성을 미리 확인한 후 실제 시스템에 적용하는 실증시험을 실시하였다. In this study, the natural frequency of the actual operating vertical pump in the P combined cycle power plant is measured and the cause of high vibration is determined by using fluid-structure coupled vibration theory. Choosing the vibration reduction plan suited for field conditions and using the numerical analysis verify effectiveness of the plan. The plan is applied to the actual pump and the empirical experiments are conducted.

BcN 멀티캐스트 기능 구조

박혁,송종태,전경규,이순석,Park, H.,Song, J.T.,Chun, K.G.,Lee, S.S. 한국전자통신연구원 2006 전자통신동향분석 Vol.21 No.6

BcN에서의 멀티캐스트 특히 IPTV 방송서비스의 서비스 및 네트워크의 요구 사항을 살펴보고 기능 구조를 도출하였다. 방송서비스의 수익은 시청률에 민감하다. 특히 접속제어를 바탕으로 하는 BcN에서 IPTV 방송서비스를 제공한다면, 표본추출 방식의 기존 방송과 달리 시청자의 거동을 전수 조사할 수 있어 수익과 시청률의 관계는 더욱 밀착될 것이다. 품질 문제로 시청자를 잃지 않기 위해서는 전달망은 패킷의 손실을 최대한 막아야 하며, 네트워크 장애 발생시 서비스의 장애가 최소한으로 억제되도록 설계되어야 한다. 따라서 망은 OAM 기능 및 경로 보호 기능을 가져야 하며, 악의적인 사용자의 공격에 대한 대비책도 갖추어야 한다. 본 고에서 논의한 기능 구조에서는 서비스 인증 후 개별 채널 변환을 L2 스위치에서 접속제어하여 적법하지 않은 사용자의 접근을 막도록 하였으며, 코어 네트워크에서는 Multicast MPLS를 사용하여 OAM 및 경로보호를 제공할 수 있도록 하였다. 또한 채널 변환에 대한 정보를 파악함으로써, 자원의 사용 및 개별 사용자의 거동을 파악할 수 있도록 하였다.

광회선분배 기술

박혁,이창형,김봉규,김광준,Park, Hyeok,Lee, Chang-Hyeong,Kim, Bong-Gyu,Kim, Gwang-Jun 한국통신학회 2001 정보와 통신 Vol.18 No.11

OXC는 정적인 점대점 광전송망에서 동적인 그물형 전광통신망으로 진화하기 위하여 망에 도입되어야 할 새로운 광네트워크 장비이다. OXC는 링크 단위의 스위칭을 하는 FXC 파장 단위의 스위칭 기능이 있으나 파장 변환 기능이 없는 WSXC, 그리고 파장 변환 기능이 있는 WIXC로 구분할 수 있으며, 이들간의 hybrid 도 가능하다. OXC 하드웨어의 중심을 이루는 것은 광스위치이다. MEMS 기술, 열광학 효과를 이용한 광도파로 기술, 전반사를 이용하는 bubble 스위치 기술 등을 사용하여 개발이 진행되고 있다. 현재까지는 이 중 3D MEMS 기술이 대용량 스위치를 구성할 가능성이 있는 기술로 받아들여지고 있다. OXC를 구성하는데 있어서 또 다른 핵심적인 기술에는 파장변환 기술이 있다. 광전 파장변환기와 전광 파장변환기 방식이 현재 연구되고 있으며 초기에는 광전변환 방식이 OXC 시스템에 적용될 가능성이 높다. 전광 파장변환기의 시스템 적용을 위해서는 좀 더 많은 연구가 필요할 것으로 보인다. OXC를 사용하는 전광통신망에서 광스위치 기술 이상으로 많은 논란이 되는 것은 망의 운용 문제이다. 현재 가장 많이 언급되는 모델은 오버레이 모델과 피어 모델이다. 오버레이 모델은 클라이언트/서버 개념에 기반한 모델인 반면 피어 모델은 광 네트워크 장비와 기존 장비를 대등한 관계로 정의한 모델이다. 각각의 모델에 대해서는 표준화 단체에 따라 약간씩 다른 입장을 취하고 있지만 상호 간에 수용 또는 타협할 점이 많다고 볼 수 있다. OXC를 포함하는 전광 통신망을 운용할 때에는 동적 연결 설정 및 해제를 위한 새로운 신호 방식이 필요하다. 이를 위하여 ITU-T 및 OIF에서 UNI와 NNI등의 인터페이스와 여기에 사용되는 신호 방식을 논의하고 있다. 그 외에도 전광 통신망 운용에 필요한 라우팅 및 파장할당 방법과 OXC를 이용한 그물형 망에서의 보호 및 복구에 대한 연구도 활발히 진행되고 있다.

일본의 도시재생정책에 있어서 관민파트너쉽에 대한 분석

박혁서(Park, Hyeok-Seo) 한국주거환경학회 2009 주거환경(한국주거환경학회논문집) Vol.7 No.2

This study highlights Osaka prefecture's inner area regeneration policy which has been pursued as a part of the urban regeneration policies in metropolitan areas and analyzes how public-private partnership induces cooperation between both sectors and serves to facilitate their pursuit for urban regeneration in view of policies. The research outcomes reveal: first, to smoothly seek an urban regeneration policy in a metropolitan area, they avoided unilateral pursuit of projects by the public but established public-private partnership so as to build consensus and cooperation among stakeholders. In case of the inner area regeneration in Osaka prefecture, public-private partnership was established at all stages of the project to promote further development of the project; Second, it is also found that the public sector helped the private sector to carry out the project without a problem and supported them in various aspects to ensure the private sector made reasonable decisions; Third, the urban regeneration policies were organically linked between the central and local governments and it in turns allowed a supporting system between different layers of the governments. Based on the findings, the study suggests policy implications of the public-private partnership for urban regeneration in a metropolitan area.

전광 광회선 분배 기술

박혁,김영화,김광준,Park, Hyuk,Kim, Young-Hwa,Kim, Kwang-Jun 한국통신학회 2002 정보와 통신 Vol.19 No.10

개인용 컴퓨터와 소프트웨어를 이용한 3차원 전산화단층영상에서의 금속 수복물에 의한 선상 오류의 제거

박혁,이희철,김기덕,박창서,Park Hyok,Lee Hee-Cheol,Kim Kee-Deog,Park Chang-Seo 대한영상치의학회 2003 Imaging Science in Dentistry Vol.33 No.3

Purpose: The purpose of this study is to evaluate the effectiveness and usefulness of newly developed personal computer-based software to eliminate the linear artifacts by the metal restorations. Materials and Methods: A 3D CT image was conventionally reconstructed using ADVANTAGE WINDOWS 2.0 3D Analysis software (GE Medical System, Milwaukee, USA) and eliminated the linear artifacts manually. Next, a 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts eliminated manually in the axial images by a skillful operator using a personal computer. A 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts were removed using a simplified algorithm program to eliminate the linear artifacts automatically in the axial images using a personal computer, abbreviating the manual editing procedure. Finally, the automatically edited reconstructed 3D images were compared to the manually edited images. Results and Conclusion: We effectively eliminated the linear artifacts automatically by this algorithm, not by the manual editing procedures, in some degree. But programs based on more complicated and accurate algorithms may lead to a nearly flawless elimination of these linear artifacts automatically.

일본의 콤팩트 도시 구축을 통한 지방도시재생에 관한 연구

박혁서(Park, Hyeok-Seo) 한국주거환경학회 2018 주거환경(한국주거환경학회논문집) Vol.16 No.2

This study analyzes urban regeneration of local cities through the establishment of compact city in Japan The population of most local cities in Japan has been decreasing due to low fertility and aging, which has caused a so-called “hallowing out” phenomenon in the central area of cities as well as urban economic recession. In addition, administrative costs per resident and maintenance costs of the infrastructure have increased due to a population decline in urban outskirt areas, where such costs used to be externalized in the past when a city was undergoing development. In order to solve the problem of declining local cities, the Special Act on Urban Regeneration was revised in 2014. The implementation of this Act institutionalized urban regeneration of local cities through the establishment of a compact city. This study undertook a comparative analysis of urban regeneration through the establishment of a centralized compact city in Aomori and the establishment of a network type multi-core compact city in Toyama. which were implemented in Japan. As a result, the following conclusions were obtained. First of all, in the case of urban regeneration in local cities through the establishment of a centralized compact city, the central area of the city is activated by attracting large-scale commercial facilities to the central area of the city. However, due to the population size in local cities and high land value of the central city area, it is difficult to attract private capital that can lead to the development of large-scale commercial facilities. Secondly, in order to develop large-scale commercial facilities in such cases, the local government often cooperate with the private sector in the form of the third sector, which can cause a large increase in the financial burden. Thirdly, it was concluded that reintegrating the population to the central area of the city is not much effective, unless the housing cost burden in the central city area and basis of the livelihood are not taken into consideration. On the other hand, the network type multi-core compact city, distributes major facilities and population in several major local areas as well as the central city area, which can take into account the present circumstances of the local city without forcefully integrating existing urban structures into one central city area. Secondly, if a traffic network is formed between the central city and major local cole area by utilizing public transportation, it will increase the floating population and vitalize central city areas as well as major multi-cores. Thirdly, it was concluded that network type multi-core compact cities can be developed faster than centralized compact cities because the former utilizes existing major multi-cores rather than integrating the existing facilities into the central city areas.

초고령사회의 고령임차인 주거문제와 일본의 주택세이프티넷제도에 관한 연구

박혁서(Park, Hyeok Seo) 한국주거환경학회 2020 주거환경(한국주거환경학회논문집) Vol.18 No.1

This research offers an analysis of the housing issues for Japanese aged lessees in the era of a super-aged society and the performance of the housing safety net system that was put in place to deal with such issues. This analysis is expected to have profound implications on the housing policy for the aged lessees in Korea that will need to be implemented in the era of the super-aged society that will come about by 2026. The analysis of this study resulted in the following conclusions. Firstly, the housing issue for the aged in the era of a super-aged society is greatly different from that in the aged society preceding the super-aged one. As most of the rental housing is occupied by the aged lessees, they been unwelcomed in the rental housing market. The main reasons for this include such problems as solitary death, failure to pay the rent and the debt-guarantee fee for the rent, all of which are linked to issues likely to occur in relation to the aged. Secondly, effectively dealing with the issues requires more than the efforts of a local government that is usually faced with tight financial constraints. This is where a subsidy by the central government is needed, and the central government has to offer a guideline on the housing safety net for the aged lessees and help local governments to make appropriate policy decisions in consideration of the rental housing market in a particular area. Thirdly, the lessors, as well as the lessees, should be supported to establish a housing safety net for the aged. To this end, it is important to promote public-private partnerships and private organizations such as housing support councils and a corporate body for housing support. Fourthly, the analysis highlighted the importance of a flexible housing safety net for the aged that is operated by the local government. In short, it is necessary to understand and approach the housing safety net issue in terms of a local rental housing market. Finally, it is thus crucial to set up online information systems which will help the aged to search for proper rental housing and enable them to make an application for moving in, as they find it physically challenging to move around in search of suitable accommodation.

통계적 여과 기법이 적용된 센서 네트워크에서 에너지 효율적인 네트워크 관리를 위한 영역별 경로 재설정 주기 결정 기법

박혁,조대호,Park, Hyuk,Cho, Tae-Ho 한국시뮬레이션학회 2011 한국시뮬레이션학회 논문지 Vol.20 No.3

대규모 센서 네트워크를 구성하는 센서 노드는 개방된 무인 환경에서 동작한다. 악의적인 공격자는 일부 센서 노드를 탈취 하여 허위 보고서를 주입할 수 있다. 통계적 여과 기법은 이러한 허위 보고서 주입 공격에 대응하기 위한 기법으로 보고서 전달 과정 중에 허위 보고서를 검출하고 여과할 수 있는 방법을 제안하였다. 통계적 여과 기법에서는 적절한 전달 경로 설정을 통하여 허위 보고서 검출 성능 향상뿐만 아니라 에너지 효율 또한 높일 수 있다. 하지만 네트워크의 위상 변화와 노드의 에너지고갈 등의 다양한 환경 변화로 인하여 전달 경로를 재설정해야 하는 경우가 빈번히 발생한다. 빈번한 경로 재설정은 과도한 에너지 소모를 유발하므로 적절한 경로 재설정 주기를 결정하는 것은 매우 중요하다. 본 논문에서는 센서 네트워크의 제안된 에너지를 효율적으로 사용하기 위한 영역별 경로 재설정 주기 결정 기법을 제안한다. 제안 기법은 퍼지 시스템을 이용해 각 영역의 경로 재설정 주기를 동적으로 결정한다. 또한 주기가 결정된 영역에 대해 적절한 보안 수준을 결정하고 해당 영역은 이를 적용하여 경로를 재설정한다. 시뮬레이션을 통하여 제안 기법이 경로 재설정에 사용되는 에너지 소모량을 최대 50% 이상 감소시켰음을 확인하였다. A large-scale sensor network usually operates in open and unattended environments, hence individual sensor node is vulnerable to various attacks. Therefore, malicious attackers can physically capture sensor nodes and inject false reports into the network easily through compromised nodes. These false reports are forwarded to the base station. The false report injection attack causes not only false alarms, but also the depletion of the restricted energy resources in a battery powered network. The statistical en-route filtering (SEF) mechanism was proposed to detect and drop false reports en route. In SEF, the choice of routing paths largely affect the energy consumption rate and the detecting power of the false report. To sustain the secure routing path, when and how to execute the path re-selection is greatly need by reason of the frequent network topology change and the nodes's limitations. In this paper, the regional path re-selection period determination method is proposed for efficient usage of the limited energy resource. A fuzzy logic system is exploited in order to dynamically determine the path re-selection period and compose the routing path. The simulation results show that up to 50% of the energy is saved by applying the proposed method.

일본의 지역관리제도와 민간조직의 지역관리활동에 관한 연구

박혁서(Park, Hyeok-Seo) 한국주거환경학회 2015 주거환경(한국주거환경학회논문집) Vol.13 No.4

This study analyzes the area management systems and management activities of private organizations in Japan. The area management activites in Japan have been organized voluntarily in the private sector for long. However, without management systems, it has been difficult to maintain these activities continuously, and it has also been difficult to secure financial resources. Due to these limitations, there have been attempts to implement area management systems in Japan since late 1990s. Among them are the TMO system and the Area Management System in the City of Osaka. The former was established in 1998 and abolished in 2006; the latter was implemented in the City of Osaka in 2014. The two are similar in that management activities are run by the private sector, but they are clearly distinguished in terms of participants and financing. This study analyzes how these differences are related to the outcomes of the area management activities. We conclude that property owners must take part in the management activites and that in order to secure stable financial resources, it is crucial to maintain profit-making business as well as imposing management fees, rather than overly relying on government subsidies.