• Title/Summary/Keyword: Investigation Board

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Evaluation of Vibration Control Performance for Active Hybrid Mount System Featuring Inertial Actuator (관성형 작동기를 이용한 능동 하이브리드 마운트 시스템의 진동제어 성능 평가)

  • Oh, Jong-Seok;Choi, Seung-Bok;Nguyen, Vien Quoc;Moon, Seok-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.8
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    • pp.768-773
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    • 2011
  • This work presents an experimental investigation on vibration control of the active hybrid mount system for naval ships. To reduce unwanted vibrations, this paper proposes an active mount which consists of rubber element, piezostack actuator and inertial mass. The rubber element supports a mass. The piezostack actuator generates a proper control force and supply it to the mount system. To avoid being broken piezostack actuator, an actuator of the proposed mount is devised as an inertial type, in which a piezostack actuator is positioned between inertial mass and rubber element. Vibration control performances of the active mount system are evaluated via experiment. To attenuate the unwanted vibrations transferred from upper mass, the feedforward control is designed. In order to implement a control experiment, the active mount system supported by four active mounts is constructed. For realization of the controller, one-chip board is manufactured and utilized. Subsequently, vibration control performances of the proposed active mount system are experimentally evaluated in frequency domains.

Investigation of NOx Reduction Ratio on SCR System for a Marine Diesel Engine (선박디젤기관용 SCR 시스템의 NOx 저감율에 관한 연구)

  • 최재성;조권회;이재현;이진욱;김정곤;양희성;고준호;박기용;장성환
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.7
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    • pp.832-838
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    • 2003
  • IMO NOx levels are generally possible to meet by means of primary on-engine measures. Nevertheless further significant follow-on reductions are likely to require a secondary after-treatment technique. SCR system is currently the only available technology proven at full scale to meet the 90% NOx reduction levels. Accordingly, maybe the use of an SCR system on board ship provides the solution to minimize this primary pollutant without increasing fuel consumption. In order to develop a practical SCR system for marine application on board ship, a primary SCR system using urea was made. The SCR system was set up on the ship. employed a two-stroke diesel engine as a main propulsion. which is a training ship in KMU (Korea Maritime Univ.). The purpose of this paper is to report the results about the basic effects of the above system parameters which is investigated from practical application through its trial use. The degree of NOx removal depends on some parameters. such as the amount of urea solution added, space velocity. reaction gas temperature and activity of catalyst. The preliminary results from trial run are presented.

A Study on Risk Analysis by Type of Ceiling Material Based on Fire Theory (화재이론에 기초한 천장재 종류별 위험성 분석에 관한 연구)

  • Kim, HyeWon;Kim, YunSeong;Lee, ByeongHeun;Jin, SeungHyeon;Koo, InHyuk;Kwon, YoungJin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.11a
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    • pp.116-117
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    • 2021
  • In general, when a building fire occurs, the heat flow rises by buoyancy, which affects the temperature rise of the ceiling. In addition, when the ceiling ignites, the fire spreads rapidly due to horizontal spread and radiant heat. According to the fire investigation, most of the large fires have a common characteristic that the fire spreads to the ceiling and causes many casualties. Therefore, it is considered that it is necessary to review the fire risk of ceiling materials used in buildings to prevent the spread of fire to the ceiling. Therefore, in this study, combustion characteristics such as the amount of heat released and ignition time of each SMC, DMC, and gypsum board were checked using a Cone Calorimeter, and the ignition temperature was calculated by substituting them into the fire theory. As a result, the ignition temperature of SMC was 449K, that of DMC was 1492K, and that of gypsum board was 677K.

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Establishment of ITS Policy Issues Investigation Method in the Road Section applied Textmining (텍스트마이닝을 활용한 도로분야 ITS 정책이슈 탐색기법 정립)

  • Oh, Chang-Seok;Lee, Yong-taeck;Ko, Minsu
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.15 no.6
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    • pp.10-23
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    • 2016
  • With requiring circumspections using big data, this study attempts to develop and apply the search method for audit issues relating to the ITS policy or program. For the foregoing, the auditing process of the board of audit and inspection was converged with the theoretical frame of boundary analysis proposed by William Dunn as an analysis tool for audit issues. Moreover, we apply the text mining technique in order to computerize the analysis tool, which is similar to the boundary analysis in the concept of approaching meta-problems. For the text mining analysis, specific model we applied the antisymmetry-symmetry compound lexeme-based LDA model based on the Latent Dirichlet Allocation(LDA) methodologies proposed by David Blei. The several prime issues were founded through a case analysis as follows: lack of collection of traffic information by the urban traffic information system, which is operated by the National Police Agency, the overlapping problems between the Ministry of Land, Infrastructure and Transport and the Advanced Traffic Management System and fabrication of the mileage on digital tachograph.

Performance Investigation of Semi-Active Control Logic to Minimize a Pointing Performance Degradation of On-Board Payload by Chattering Effects (Chattering에 의한 위성 탑재체 지향성능저하 최소화를 위한 반능동제어기법 성능분석)

  • Oh, Hyun-Ung;Choi, Young-Jun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.9
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    • pp.882-889
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    • 2010
  • Semi-active vibration control is one of the attractive control methods for space application due to its robustness as passive damping system and much higher damping performance than passive system. However, a chattering induced by the sudden variation of damping force at the time of On-Off switching of semi-active control device degrades pointing performance of the on-board payload. In this paper, to enhance the pointing performance of the on-board payload, we proposed a semi-active vibration isolation with a strategy for attenuating chattering effect. Numerical simulation results using simplified analysis model indicated that the proposed semi-active control strategy produced much better isolation performance than the conventional Bang-Bang control semi-active control laws derived from skyhook and LQ theories.

'Survey on Bacteriological Contamination of Moving Tavern in Seoul Area' ('노상주점의 위생상태에 관한 미생물학적 조사')

  • Yu Byong Tai
    • Journal of environmental and Sanitary engineering
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    • v.1 no.1 s.1
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    • pp.59-67
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    • 1986
  • This sanitary survey was carried out to investigate the bacteriological contamination of cooking utensils and foods of moving tavern in eight sample sites of Seoul area. The results of survey were as follows: 1. The counts by means of total bacteria in cooking utensils and food samples by standard plate count method were as follow: $5.6\times10^5$ per gm in dishcloth, $3.1\times10^6$ per ml in dishwater. In food samples, $5.4\times10^5$ per gm in meat was higher than other samples. 2. The average counts total coliform and fecal coliform in samples by MPN method were as follow: $3.4\times10^4$ MPN per 100ml, and $1.3\times10^2$ MPN per 100ml in chopping board, $6.1\times10^4$MPN per gm and $1.0\times10^2$ MPN per gm in dishcloth, $1.8\times10^5$ MPN per 100ml and $6.1\times10^2$ MPN per 100ml in dishwater. In food samples, $3.1\times10^4$MPN per gm and $2.0\times10^2$ MPN per gm in meat was higher than other samples. 3. The counts by means of Pseudomonas in samples by MPN method were as follow: $2.8\times10^3$ MPN per 100ml in chopping board, $4.7\times10^3$ MPN per gm in dishcloth $5.6\times10^3$ MPN per 100ml in dishwater. In food samples, $2.4\times10^3$ MPN per gm in shellfish was higher than other samples. 4. Isolation cases of Food poisoning organisms from samples were as follow: Staphylococci was detected 9 cases $(17.6\%)$ in chopping board, 7 cases $(13.6\%)$ in dishcloth. In food samples, 9 cases $(25.7\%)$ in meat, 1 case $(4\%)$ in fish samples. Salmonella was detected 2 cases $(3.9\%)$ in dishwater, 1 case in meat samples.

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Development of 50W High Quality Factor Printed Circuit Board Coils for a 6.78MHz, 60cm Air-gap Wireless Power Transfer System (6.78MHz, 거리 60cm, 50W급 무선 전력 전송 시스템용 High Quality Factor PCB 코일 개발)

  • Lee, Seung-Hwan;Yi, Kyung-Pyo
    • Journal of the Korean Society for Railway
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    • v.19 no.4
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    • pp.468-479
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    • 2016
  • In order to supply power to online monitoring systems that are attached to high voltage catenary or overhead wires, a wireless power transfer system is required that is able to transmit power over the insulation gap. Such wireless power transfer systems have transmitter and receiver coils that have diameters of over 10cm. This paper focused on an investigation of the sources of loss in the coils when the coils are fabricated using printed circuit board technology. Using finite element simulation results, it has been shown that the dielectric loss in the substrate was the dominant source of the total loss. It has been demonstrated that the selection of a proper dielectric material was the most critical factor in reducing the loss. For further reduction of the loss, the distributed tuning capacitor method and the slotting of the inter-turn spaces have been proposed. For the evaluation of the proposed methods, four coils have been fabricated and their equivalent series resistances and quality factors were measured. Measured quality factors were greater than 300, which means that these devices will be helpful in achieving high coil-to-coil efficiency.

Comparison of live shrimp bait catch efficiency in single line fishery

  • Koo, Myungsung;Munechika, Ishizaki;Cho, Samkwang;Bae, Bongseong;Cha, Bongjin
    • Fisheries and Aquatic Sciences
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    • v.24 no.11
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    • pp.383-389
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    • 2021
  • On the southern coast of South Korea, dark-banded rockfish, sea bass, and red seabream are caught by single-line fishing. In particular, red seabream and sea bass are caught in the Jeollanam-do region using gear with attached fishing hooks, such as longline and single-line gear, with live shrimp as bait. The objective of this study was to compare the catch efficiency of two types of live shrimp (naturally grown Shiba shrimp [Metapenaeus joyneri] and cultured whiteleg shrimp [Litopenaeus vannamei]) used as bait. The investigation included interviews, on-board surveys, and water tank experiments. Interviews were conducted with relevant parties to determine the preference for live shrimp as bait, and the results showed a greater preference for cultured whiteleg shrimp. Further, an on-board survey was conducted to compare catch efficiency between these two types of live shrimp bait for single-line fishing. The on-board investigations were conducted once or twice a month between June and October. In total, the amounts of fish caught using naturally grown Shiba shrimp and cultured whiteleg shrimp were 56 and 52, respectively. Of these, the numbers of sea bass, the primary target fish species, caught using naturally grown Shiba shrimp and cultured whiteleg shrimp were 43 and 40, respectively. Thus, the results showed that there was almost no difference in the number of fish caught based on the bait used. However, according to a water tank experiment, cultured whiteleg shrimp survived longer than naturally grown Shiba shrimp.

A Study on the Improvement of Effectiveness of KOSHA 18001 in Construction Industry (건설업 KOSHA 18001 인증제도의 실효성 제고에 관한 연구)

  • Lee, Jin Seop;Lee, Myeong Gu;Lee, Dong Yul;Oh, Tae Keun
    • Journal of the Korean Society of Safety
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    • v.30 no.3
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    • pp.80-84
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    • 2015
  • The industrial accidents in the construction business have decreased on the basis of the accreditation of KOSHA 18001, one of the occupational health and safety management system. However, the interest and investment into the KOSHA 18001 has grown down because of the worsened construction business so that the construction companies that maintain the system as a mere formality has begun to be displayed. In this regard, this study performed the interview with the internal and external review board as well as the question investigation from the persons concerned in order to apprehend the current problems in the KOSHA 18001. First of all, the internal reviewers in the KOSHA are lack in the comparison with the number of new and renew accreditation. Secondly, many persons concerned with the KOSHA has required the quantitative criteria for the accreditation. Consequently, the manpower supplement associated with the external reviewers, the grading evaluation would be strong solutions to improve the effectiveness of KOSHA 18001.

A Study on the Investigation of Overseas Case in Street Furnitures of Public Design (공공디자인의 가로시설물에 대한 해외 사례의 조사 연구)

  • Cho, Won-Seok;Kim, Heung-Gee
    • Journal of the Korean Institute of Rural Architecture
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    • v.11 no.3
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    • pp.11-18
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    • 2009
  • The purpose of this paper is to find out the investigation of overseas case in Street Furnitures of Public Design. Thus this research regions select among the waterfront cities; Tokyo/Yokohama(Japan), Nies/Cannes(France), Shanghai(China), Vancouver(Canada), in addition to the city of art and romance; Paris. Above all, it is necessary to study concept of public design and definition of street furnitures. The survey data collected from forenamed cities and the items of street furnitures are various installments such as kiosk, bench, bollard, litter-bin, sign board, toilet, bus/taxi station, fence, shelter, lighting column, fountain, telephone-booth, clock-tower, automaton, bicycle stand, playing object etc. In this study street spaces are analysed that is related to regional surroundings and pedestrian's culture. Consequently, design trend of street furniture in foreign case analysis are going into thoroughly modern image as well as checking of form, color, material and maintenance system. According to the above findings, this paper will provide basic data for establishing of the street furniture and improving of public design to the regional citizen, local government officials and regional experts.

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