• 대한전자공학회논문지TC
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• 제47권7호
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• pp.118-127
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• 2010

패킷 기반의 TCP/IP 프로토콜 기반으로 구축된 인터넷 환경은 30년 넘게 사용되어 왔으나, 향후 통신환경의 급격한 변화와 다양한 사용자 요구사항의 증대로 인해 프로토콜 확장의 제약으로 인한 근본적인 문제점을 나타나게 될 것이다. 이를 해결하기 위해 Clean Slate 설계 방법에 기반을 둔 미래인터넷 연구가 진행되고 있고, 이를 실험하고 검증하기 위한 대규모 테스트베드 구축이 이루어질 것이다. 이를 위한 오픈 플로우 스위치 기술은 기존에 포설된 네트워크 장비를 활용하면서, 인터넷 트래픽에 영향을 주지 않고 독립적인 프로토콜을 시험할 수 있도록 하는 새로운 기술로 제안되었다. 국내에서도 테스트베드 구축의 한 방법으로 NetFPGA기반 오픈 플로우 스위치를 활용한 망구성이 연구되고 있으며 이러한 구조에서 인터넷망을 통한 오픈플로우 스위치 간 연결이 이루어지기 위해서는 오픈 플로우 스위치 간 논리적인 터널링이 제공되어야 한다. 이에 대한 해결책으로 본 논문에서는 NetFPGA 기반의 캡슐레이터를 구현하여 국내연구망인 KOREN에 구현된 여러 오픈 플로우 사이트 간에 MAC in IP 터널링이 이루어 질 수 있도록 하였고 이의 성능을 측정하였다. 측정 결과 기존 소프트웨어 기반의 캡슐레이터에 비해 성능이 향상되었음을 확인하였고, 미래인터넷 기술을 실험할 수 있는 테스트 베드로 활용할 수 있음을 보였다.

• 수산해양기술연구
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• 제51권2호
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• pp.203-211
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• 2015

The purpose of this study is to identify the flow resistance of the bottom pair trawl nets. The bottom pair trawl nets being used in fishing vessel (100G/T, 550ps) was selected as a full-scale net, and 1/10, 1/25 and 1/50 of the model nets were made. Converted into the full-scale net by Tauti's modeling rule and Kim's modeling rule, when resistance coefficient k of each net was calculated by substituting into above equation for flow resistance R and wall area of nets S values of each net ${\upsilon}$. Because resistant coefficient k decreases exponentially according as flow velocity ${\upsilon}$ increases to make $k=c{\upsilon}^{-m}$, c and m values of each net were compared. As a result, as the model was smaller, c and m values was smaller in the two rule into standard of 1/10 model value, decrease degree of 1/25 model was almost same in the two rule, decrease degree of 1/50 model was very big in Tauti's modeling rule. Therefore, in the result of experiment, because average of c and m values for similarly 1/10 and 1/25 model were given $c=4.9(kgf{\cdot}s^2/m^4)$ and m=0.45, R (kgf) of bottom pair trawl net could show $R=4.9S{\upsilon}^{1.55}$ using these values. As in the order of cod-end, wing and bag part for 1/25 and 1/50 model net were removed in turn, measured flow resistance of each, converted into the full-scale, total resistance of the net and the resistance of each part net were calculated. The resistance ratio of each part for total net was not same in 1/25 and 1/50 model each other, but average of two nets was perfectly same area ratio of each part as the wing, bag and cod-end part was 43%, 45% and 12%. However, the resistance of each part divided area of the part, calculated the resistance of per unit area, wing and bag part were not big difference each other, while the resistance of cod-end part was very large.

• 수산해양기술연구
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• 제52권4호
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• pp.308-317
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• 2016

The tail flip of the decapod shrimp is a main feature in escaping behavior from the mesh of the codend in the trawl. The characteristics of tail flip in target prawn was observed and analyzed in a water tunnel in respect of flow condition and mesh penetration by a high speed video camera (500 fps). The tail bending angle or bending time in static water was significantly different than in flow water (0.7 m/s) and resultantly the angular velocity in static water was significantly higher than in flow water when carapace was fixed condition. When escaping through vertical traverse net panel in water flow the relative moving angle and relative passing angle to flow direction during tail flip, it significantly decreases the number of shrimps escaping than the case of blocking shrimp. The bending angles of tail flip between net blocking and passing through mesh were not significantly different while the bending time of shrimp passing through mesh was significantly longer than when shrimp blocking on the net. Accordingly the angular velocity of passing through mesh was significantly slower than blocking on the net although the angular velocity of the tail flip was not significantly related with carapace length. The main feature of tail flip for mesh penetration was considered as smaller diagonal direction as moving and passing angle in relation to net panel as right angle to flow direction rather than the angular velocity of tail flip.

• 대한기계학회논문집A
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• 제26권2호
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• pp.291-299
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• 2002

This paper characterizes hi-directionally oscillating flow in planar microdiffusers in order to evaluate the frequency-dependent flow rectification performance of the microdiffusers. In the theoretical study, we analyze a hi-directionally oscillating flow in the planar microdiffuser. In the experimental study, we fabricate two different microdiffuser prototypes, having different neck widths of 100 ㎛ (D100) and 300 ㎛(D300), respectively. The experimental net flow rates are measured as 116.6 $\mu$ι/min. and 344.4 $\mu$ι/min. for D100 and D300, respectively. The experimental flow rate of D300 decreases at the oscillating flow frequencies higher than 90Hz, at which the net boundary layer thickness is reduced to the microdiffuser neck width. It is experimentally verified that the flow rectification performance and the net flow rate of the microdiffusers tend to decrease when the boundary layer thickness is smaller than the diffuser neck width.

• Nuclear Engineering and Technology
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• 제44권8호
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• pp.929-938
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• 2012

The Computerized Procedure System (CPS) is one of the primary operating support systems in the digital Main Control Room. The CPS displays procedure on the computer screen in the form of a flow chart, and displays plant operating information along with procedure instructions. It also supports operator decision making by providing a system decision. A procedure flow should be correct and reliable, as an error would lead to operator misjudgment and inadequate control. In this paper we present a modeling for the CPS that enables formal verification based on Petri nets. The proposed State Token Petri Nets (STPN) also support modeling of a procedure flow that has various interruptions by the operator, according to the plant condition. STPN modeling is compared with Coloured Petri net when they are applied to Emergency Operating Computerized Procedure. A converting program for Computerized Procedure (CP) to STPN has been also developed. The formal verification and validation methods of CP with STPN increase the safety of a nuclear power plant and provide digital quality assurance means that are needed when the role and function of the CPS is increasing.

• 디지털산업정보학회논문지
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• 제19권3호
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• pp.245-251
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• 2023

Facial expression recognition plays a significant role in understanding human emotional states. With the advancement of AI and computer vision technologies, extensive research has been conducted in various fields, including improving customer service, medical diagnosis, and assessing learners' understanding in education. In this study, we develop a model that can infer emotions in real-time from a webcam using transfer learning with TensorFlow.js and MobileNet. While existing studies focus on achieving high accuracy using deep learning models, these models often require substantial resources due to their complex structure and computational demands. Consequently, there is a growing interest in developing lightweight deep learning models and transfer learning methods for restricted environments such as web browsers and edge devices. By employing MobileNet as the base model and performing transfer learning, our study develops a deep learning transfer model utilizing JavaScript-based TensorFlow.js, which can predict emotions in real-time using facial input from a webcam. This transfer model provides a foundation for implementing facial expression recognition in resource-constrained environments such as web and mobile applications, enabling its application in various industries.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.329-332
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• 1991

This paper presents an algorithm to reduce the time to solve Power Equations using a Neural Net. The Neural Net is trained with samples obtained through the conventional AC Load Flow. With these samples, the Neural Net is constructed and has the function of a linear interpolation network. Given arbitrary load level, this Neural Net generates voltage magnitudes and angles which are linear interpolation of real and reactive powers. Obtained voltage magnitudes and angles are substituted to Power Equations, Real and reactive powers are found. Thus, a new sample is generated. This new experience modifies weight matrix. Continuing to modify the weight matrix, the correct solution is achieved. comparing this method with AC Load flow, this method is faster. If we consider parallel processing, this method is far faster than conventional ones.

• 수산해양기술연구
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• 제43권3호
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• pp.192-205
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• 2007

The objective of this study was to investigate the optimal shapes and arrangements of sinkers attached to net cages to prevent their deformation in a current. A series of model experiments were conducted in a circulating water channel, using 5 different types of sinker(high-weighted ball, low-weighted ball, columntype, egg-shaped and iron bar-framed) and 2 types of square net cage constructed from both Nylon Raschel netting and Nylon knotted netting, on a 1/20th scale. The deflection of the model nets against the flow was smallest with the iron bar-framed weight compared to the other four types of sinker. It was expected that the optimal shapes of sinkers would be either the ball or egg-shape; however, iron bar-framed weight actually had larger drag forces. The dispersed deployment of sinkers on the bottom frames of model net cages performed better with relatively slow flows, while the concentrated deployment at 4 corners functioned better with relatively fast flows, in preventing the nets from becoming severely deformed. The deformation of the net cages was larger for the Nylon knotted netting than the Nylon Raschel netting. With respect to flow resistance, the Nylon Raschel netting, rather than the Nylon knotted netting, was more suitable for construction of net cages.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2005년도 가을 학술발표논문집 Vol.32 No.2 (1)
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• pp.283-285
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• 2005

인터넷 사용자의 증가와 항께 인터넷 트래픽 역시 기하급수적으로 증가하고 있다. 이에 따라 네트워크 보안, 트래픽의 특성 분석, 사용자별/응용별 과금, 및 트래픽 엔지니어링을 수행하기 위해서는 네트원크 모니터링 도구가 필수적이다. 그러나, 기존 연구에 많이 사용되고 있는 Cisco NetFlow v5는 포트번호를 기반으로 응용 트래픽을 분류하여 분석할 수 있지만, IPv6과 MPLS 등의 다양한 프로토콜에 대한 트래픽을 분석할 수는 없다. 따라서, IETF에서는 IPFIX표준을 제정하여 확장성 있고 SCTP/TCP 전송 프로토콜을 이용하여 신뢰성있는 플로우 측정 프레임워크를 제시하였다. 본 논문은 Cisco NetFlow v5와 NetFlow v9(IPFIX의 기본 프로토콜)를 모두 지원하여 IPv4/IPv6 트래픽을 실시간으로 분석할 수 있는 플로우 기반 트래픽 모니터링 도구를 구현하였고, 실험을 통하여 IPv6 트래픽을 신뢰성있게 분석할 수 있다는 것을 보였다.

• Management Science and Financial Engineering
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• 제3권1호
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• pp.15-38
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• 1997

In a flexible manufacturing system, a cell controller is able to identify and evaluate a number of alternative decisions to meet the objectives set by the factory level controller. In this paper, a Petri net-based cell controller is presented to accomplish this task. A static model is developed by using the Integrated Computer Aided Definition(IDEF0) method to represent clear functional relationships among the objects of the system. Based on the static model, two Petri net models are developed for the physical part flow and for the information flow. Multiple decision alternatives are generated from the physical part flow model and are synchronized with the information flow model for execution of the selected alternative.