• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.163-173
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• 2001

The dynamic behavior characteristics of a small fishing crane for inshore and coastal fishing vessels was experimentally analyzed in order to improve the fishing operation and to reduce considerably manual work of fisherman. The small fishing crane was designed to be controlled electro-hydraulically by means of proportional valves and solenoid valves, and also to be controlled the speed of each operation. The dynamic behavior characteristics was investigated by measuring the changes of parameters such as oil pressure, swing angle of load, load tension, the lifting angle and the swing angle of crane arm when the arms extended in a side way was given a test load. The results obtained are summarized as follows: 1. The designed small fishing crane can be proportionally controlled by means of proportional valves and rapidly by operating the solenoid valves, respectively. The capacity, turning angle, maximum reach of crane were 2 T-M, $180^\circ$, 3.7m, respectively. 2. The vertical change of crane arm on the extension of lifting cylinder was $1.2^\circ$/cm, and the swing speed of crane arm due to the extension of swing cylinder by on/off operations of solenoid valves was $15^\circ$/sec, with the swing period of 1.4 sec and the angle fluctuation of $\pm$11.0$^{\circ}$. 3. When changing simultaneously the horizontal and vertical positions of the lifting load by on/off operations of solenoid valves, the swing and lifting speeds of crane arm were $4.46^\circ$/sec and $6.4^\circ$/sec, respectively. 4. The movements of the designed crane were particularly smooth as they are controlled with the aid of proportional valves than by means of solenoid valves.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.78-80
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• 2021

This study is based on Degree of Recognition and AHP surveys for experts, this study investigates changes in the demand of seafarers in response to changes in the shipping industry environment in which Maritime Autonomous Surface Ships(MASS) emerge according to the application of the fourth industrial revolution technology to ships, and it looks into changes in seafarers' skills. It also analyzes and proposes a plan for cultivating seafarers accordingly. As a result of Degree of Recognition and AHP analysis, it is analyzed that a new training system is required because the current training and education system may cover the job competencies of emergency response, caution and danger navigation, general sailing, cargo handling, seaworthiness maintenance, emergency response, and ship maintenance and management, but jobs such as remote control, monitoring diagnosis, device management capability, and big data analysis require competency for unmanned and shore based control.By evaluating the importance of change factors in the duties of seafarers in Maritime Autonomous Surface Ships, this study provides information on seafarers educational institutions response strategies for nurturing seafarers and prioritization of resource allocation, etc. The importance of factors was compared and evaluated to suggest changes in the duties of seafarers and methods of nurturing seafarers according to the introduction of Maritime Autonomous Surface Ships.It is expected that this study is meaningful as it systematically derived the duties and competency factors of seafarers of Maritime Autonomous Surface Ships from a practical point of view and analyzed the perception level of each relevant expert to diagnose expert-level responses to the introduction of Maritime Autonomous Surface Ships.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.74-81
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• 2024

In the near future, autonomous ships, ships controlled by shore remote control centers, and ships operated by navigators will coexist and operate the sea together. In the advent of this situation, a method is required to evaluate the safety of the maritime traffic environment. Therefore, in this study, a plan to evaluate the safety of navigation through ship control simulation was proposed in a maritime environment, where ships directly controlled by navigators and autonomous ships coexisted, using autonomous operation technology. Own ship was designed to have autonomous operational functions by learning the MMG model based on the six-DOF motion with the PPO algorithm, an in-depth reinforcement learning technique. The target ship constructed maritime traffic modeling data based on the maritime traffic data of the sea area to be evaluated and designed autonomous operational functions to be implemented in a simulation space. A numerical model was established by collecting date on tide, wave, current, and wind from the maritime meteorological database. A maritime meteorology model was created based on this and designed to reproduce maritime meteorology on the simulator. Finally, the safety evaluation proposed a system that enabled the risk of collision through vessel traffic flow simulation in ship control simulation while maintaining the existing evaluation method.

• Radiation Oncology Journal
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• v.16 no.1
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• pp.63-69
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• 1998

Purpose : This study is to evaluate the efficacy of small bowel displacement system(SBDS) in post-operative pelvic radiation therapy(RT) of rectal cancer patients by measurement of small bowel volume included in the radiation fields receiving therapeutic dose. Materials and Method : Ten consecutive new rectal cancer patients referred to the department of Radiation Oncology of Samsung Medical Center in May of 1997 were included in this study. All patients were asked to drink $Castrographin^(R)$ before simulation and were laid prone for conventional simulation and CT scans with and without SBDS. The volume of opacified small bowel on CT scans, which was to be included in the radiation fields receiving therapeutic dose, was measured using Picture archiving and communication system (PACS). Results : The average small bowel volumes with and without SBDS were 176.0ml(5.2-415.6ml) and 185.1ml(54.5-434.2ml), respectively The changes of small bowel volume with SBDS compared to those without SBDS were more than $10\%$ decrease in three, less than 10% decrease in two, less than $10\%$ increase in three, and more than $10\%$ increase in two patients. Conclusion : No significant advantage of using SBDS in post-operative pelvic RT for rectal cancer patients has been shown by small bowel volume measurement using CT scan considering additional effort and time needed for simulation and treatment setup.

• Journal of the Korea Computer Industry Society
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• v.5 no.3
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• pp.393-404
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• 2004

Recently, public home have used a more than two computer connected with network, and several home appliances using independently with internet or network are developing to be related closely with the network. Therefore, the home utilized for a simple terminal of the global network in the past is being expanded to another part of the sub network. For a variety of connecting home-area protocols with the existing existing network, we require a new Residential Gateway(RG) that does not only make the home-area network operating in the sub network but also connects to the external network. In this paper, RG has intrinsic limits against flexible service due to IP address assignment and hardware capacity. In order to solve this problem in the RG, we propose a Management Server(MS). The MS that offers the integrated managements and control services for a variety of devices connected the RG in the home-area. It can not only solve the dynamic IP address assigning problem but also assigns private IP addresses to the home network devices through the Network Address Translation(NAT). It also provides somewhat useful functions for the home network and the RG for other additional services. <중략> The MS is using a SNMP protocol for managing the RG in the domain, a polling method of the MS and the RG compose a sequence polling method, a polling method using a multi-process and a multi-thread. In this paper, we introduce a problem with polling method separately, show a polling method between the MS and the RG using a multi-thread.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.914-923
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• 2009

Helix antennas have been widely applied to satellite TT&C, data communication and GPS receiver systems onboard military, remote sensing and communication purpose satellites. The helix antennas are known to be convenient to control impedance and radiation coverage characteristics with a maximum directivity in satellite z-axis. Waveguide horn is commonly used for radar system that needs ultra-wideband pulse for exploration ground radar and electromagnetic disability measurement etc. It has high efficiency and low reflection characteristics provided by the low-profile shape and suppressed radiation distortion. In this paper, a waveguide horn structure incorporated with helix antenna design is proposed for satellite applications that require ultra-wideband pulse radar and high rate RF data communication link to ground station over wide coverage area. The main design concern is to synthesize variable beam forming pattern based on modified horn-helix combination helicone structure such that multi-mission antenna is implemented applicable for TT&C, earth observation, high data rate transmission. Waveguide horn helps to reduce the overall antenna structure size by introduction fold type reflector connected to the tapered helix antenna. The next generation KOMPSAT satellite currently under development requires high-performance precision attitude control system. We present an initial design of a hybrid hern-helix antenna structure suitable for efficient RF communication module design of multi-purpose satellite systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.845-848
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• 2013

Due to intense climate changes and extreme weather conditions a noticeable decrease has been observed in the growth of certain plants. The indoor plant factories would have certain benefits including increase in crop yield, reduction in distribution cost, and maintains the healthy freshness level of the agricultural product. Recently, an artificial light source with optimum wavelength is spot lighted to fulfill the need of light for the indoor plant factories. The energy efficient light emitting diodes (LED) provide the essential light energy for the proper growth of indoor cultivated plants. This work focuses to utilize ubiquitous sensors network(USN) in providing suitable environment for the proper growth of agricultural product inside the indoor plant factory. The proposed system makes use of sensors and actuators, communicating each other through WPAN, ZigBee network. The proposed system obscured the traditional indoor plant factories with easy installation and wireless connectivity of the sensors and actuators along with eliminating the web of wires reducing the initial installation and maintenance cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.7
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• pp.630-642
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• 2013

To transmit vital signal stream of mobile patients remotely, it requires mobility of patient and watcher, sensing function of patient's abnormal symptom and self-organizing service binding of related computing resources. In the existing relative researches, the vital signal stream is transmitted as a centralized approach which exposure the single point of failure itself and incur data traffic to central server although it is localized service. Self-organizing middleware platform based on heterogenous overlay network is a middleware platform which can transmit real-time data from sensor device(including vital signal measure devices) to Smartphone, TV, PC and external system through overlay network applied self-organizing mechanism. It can transmit and save vital signal stream from sensor device autonomically without arbitration of management server and several receiving devices can simultaneously receive and display through interaction of nodes in real-time.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.577-577
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• 2016

기후변화는 전 지구적 현상으로 이로 인한 홍수피해는 심화되고 있다. 기후변화 정부간 협의체 5차 보고서(IPCC, 2014)에 의하면 1980년대 이전 세계 평균 홍수피해액은 70억 달러 수준이었으나 2011년에는 240억 달러로 크게 증가한 것으로 나타났다. 2013년 필리핀에 태풍 '하이옌' 내습으로 인해 6,200여명이 사망하고, 2천여명이 실종되는 피해가 발생하였다. 국내의 경우 2014년 8월 경남 부산지역에는 시간당 130mm가 넘는 국지성 호우에 따라 차량 4,000여대가 침수, 5명 사망 등 약 125억원의 재산피해가 발생한 바 있다. 국회예산정책처(2012)와 소방방재청(2014)에 따르면, 자연재해 중 집중호우 및 태풍에 의한 호우피해가 85%를 차지하였으며, 전국 하천 피해액의 98.7%가 지방 및 소하천에서 발생하고 있다. 이에 따라 중소하천과 같이 소외된 지역의 물복지 향상을 위해서는 홍수재해 상황에 대하여 선제적 효과적 대응을 위한 과학적 체계적인 홍수통합관리 체계의 구축이 요구되고 있다. 특히 홍수관련 유관기관 자료를 연계한 실시간 상 하류 수문상황 모니터링, 홍수분석 및 하천수위별 대응기준 수립, 배수펌프장 등 수리시설원격 제어 등을 포함하는 홍수 통합관리체계 구축과 같은 비구조적 대책의 수립이 제방정비, 저류조 등 구조적 대책과 병행하여 반드시 추진되어야 한다. 이에 K-water는 ICT기반의 물관리기술력과 경험을 활용하여, 인력 기술력 예산 부족 등 열악한 재난관리 여건으로 어려움을 겪고 있는 지자체와 협업을 통해 홍수통합관리체계 구축을 지원하고 있다. 홍수통합관리체계 구축은 지자체 상 하류의 다양한 재난정보를 수집 통합하고, 수집된 정보를 활용한 홍수분석 및 홍수 대응기준 수립을 통해 예방적 재난대응 체계를 마련하는 것으로, K-water는 지난 2010년 남원시를 시작으로 무주군, 군산시, 진안군 등 21개 지자체의 홍수재해 통합관리체계 구축을 지원하고 있다. 특히 남원시의 경우 본 사업을 통한 시스템 구축후 홍수피해액이 50% 감소한 것으로 확인되는 등 재난관련 골든타임을 확보하고 홍수피해 최소화를 위한 홍수재해 통합관리 체계 구축은 이제 선택이 아닌 필수라 할 수 있다. K-water는 물관리 전문 공기업으로써의 역할을 다하고, 예방 중심의 재난관리 체계 마련을 위해 '지자체 맞춤형 홍수통합관리체계' 구축 지원을 지속적으로 확대해나갈 예정이다.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.10
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• pp.373-380
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• 2022

This paper presents a deep learning based group synchronization that supports networked immersive interactions between remote users. The goal of group synchronization is to enable all participants to synchronously interact with others for increasing user presence Most previous methods focus on NTP-based clock synchronization to enhance time accuracy. Moving average filters are used to control media playout time on the synchronization server. As an example, the exponentially weighted moving average(EWMA) would be able to track and estimate accurate playout time if the changes in input data are not significant. However it needs more time to be stable for any given change over time due to codec and system loads or fluctuations in network status. To tackle this problem, this work proposes the Deep Group Synchronization(DeepGroupSync), a group synchronization based on deep learning that models important features from the data. This model consists of two Gated Recurrent Unit(GRU) layers and one fully-connected layer, which predicts an optimal playout time by utilizing the sequential playout delays. The experiments are conducted with an existing method that uses the EWMA and the proposed method that uses the DeepGroupSync. The results show that the proposed method are more robust against unpredictable or rapid network condition changes than the existing method.