• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.116-121
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• 2019

The LVDT (Linear Variable Displacement Transducer) type sensor used for the existing ship's steering gear is simple on / off that does not perform proportional control operation to the control & unloading device. When the main spool is located at both extremes, It is reflected in the price by using an expensive sensor for import. In this paper, the Hall Effect Sensor is applied to Hydraulic Locking Alarm to analyze classification rules, structure, characteristics and operation principle of valves, and research on localization development in terms of cost reduction. The comparative analysis of the existing prototypes and the cause analysis of the problems were carried out, and the structural analysis showed satisfactory results within the allowable stress range. In addition, it was verified through experiments that the actual operation is realized by applying the actual developed product, and it was confirmed that the load on the maximum value exceeds the allowable maximum load even in the case of the universal tensile test in preparation for the departure of the rod casing.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.428-439
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• 2020

The continuous development of information and communication technologies has resulted in an exponential increase in data. Consequently, technologies related to data analysis are growing in importance. The shipbuilding industry has high production uncertainty and variability, which has created an urgent need for data analysis techniques, such as machine learning. In particular, the industry cannot effectively respond to changes in the production-related standard time information systems, such as the basic cycle time and lead time. Improvement measures are necessary to enable the industry to respond swiftly to changes in the production environment. In this study, the lead times for fabrication, assembly of ship block, spool fabrication and painting were predicted using machine learning technology to propose a new management method for the process lead time using a master data system for the time element in the production data. Data preprocessing was performed in various ways using R and Python, which are open source programming languages, and process variables were selected considering their relationships with the lead time through correlation analysis and analysis of variables. Various machine learning, deep learning, and ensemble learning algorithms were applied to create the lead time prediction models. In addition, the applicability of the proposed machine learning methodology to standard work hour prediction was verified by evaluating the prediction models using the evaluation criteria, such as the Mean Absolute Percentage Error (MAPE) and Root Mean Squared Logarithmic Error (RMSLE).

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.192-200
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• 2002

Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions for passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed, which is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper that offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-off becomes smooth when the fixed orifice size increases, which means that the blow-off slope is controllable using the fixed orifice size. The damping force variance is wide and continuous, and is controlled by the spool opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.411-419
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• 1999

EBPP는 소비자, 사업자간에 고지서 발송, 접수 및 지불을 네트워크를 통하여 전자적으로 처리하는데 필요한 환경을 의미하며, 인터넷을 기반으로 하여 전자우편 혹은 웹 페이지를 통하여 고지서를 처리한다 EBPP 시스템은 크게 소비자, 사업자 그리고 은행간의 거래로 이루어 지지만 컴퓨터 및 인터넷의 보급의 한계 등의 문제로 현재로서 모든 고지서를 전자적으로 처리하는 것은 무리가 따른다. 그럼에도 불구하고 EBPP 시스템은 1) 경쟁력 확보를 위해 기업/금융 기관들이 인터넷을 통한 고품질 서비스 개발에 주력하는 추세이고, 2) 고객과의 보다 긴밀한 관계 유지를 위한 수단 제공하며, 3) 인터넷 등 온라인 통신 인구가 급격한 증가(2701년에 전체 인구의 약 50%가 활용할 것으로 전망)하고 있으며,4) 소비자를게 보다 편리한 지불방법 제시해주며, 5) 또 다른 마케팅 매체로 활용 가능하므로 앞으로의 전망이 매우 밝다. EBPP시스템은 크게 금융기관, 기업, 소비자 부분으로 구성되며, 소비자와 접촉 방법으로는 대표적으로 Web과 전자우편을 생각할 수 있으며, EBPP 시스템을 구축하기 위해서는 기본적으로 상접 혹은 기업에서 청구에 필요한 정보를 등록시키는 통합 청구서버(Bill consolidation server), 소비자에게 청구 가능한 정보를 갖고있는 청구 제시서버 (Bill presentment server), 소비자의 지불요청에 따라 은행으로부터 지불을 요구하는 지불서버(Payment gateway) 등이 필요하며, 이들 각각의 서버들의 구성 요소들은 제공하는 서비스에 따라 달라질 수 있다. 통합 청구서버에서 청구 제시서버로 전송되는 청구 건은 통상적으로 실시간 처리되는 것이 아니라 통합 청구서버에 존재하는 Spool DB에 저장되어 그 양이 일정한도를 넘어서면 자동 전송되도록 하여, 망의 할용도를 높이는 역할을 수행한다. 청구 제시서버의 DB에 등록된 청구 건은 인터넷을 통해 소비자에게 청구되며, 소비자에게 전송 되는 청구서는 사용자DB를 참조하여 사용자가 미리 정의한 원하는 형태로 변환되어 전달되며, 필요시 암호화 과정을 거치는 것이 가능해야 한다. 전송된 청구서는 전자우편의 경우, 암호해독이 가능한 전용 브라우저를 통해 열람 되며, 이는 다시 전용 브라우저를 통해 지불인증이 승인되어 청구 제시서버에게 전송된다. EBPP 시스템의 제어 흐름은 크게 기업이 청구 정보를 소비자에게 제시하는 흐름과 소비자의 지불 승인으로 인해 기업이 은행에 지불을 요구하는 흐름으로 구분할 수 있다. 본 논문에서는 통합 청구서버 및 정구 제시서버의 역할 및 구성 요소들에 대해 서술하고, EBPP 시스템과 연동하여야 하는 메일 서버와의 상호 작용에 대해 서술할 것이다. 본 시스템을 아직 구현이 되지 않은 관계로 시스템의 성능 등의 수치적 결과를 제시할 수 없는 상태다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1183-1188
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• 2013

The reliability of hydraulic equipment used in power plants is especially important because failures that occur in the power plant can have a great ripple effect on human lives and financial losses. In this study, specimens using the materials used in the spool and sleeve of hydraulic valves of power plants have been produced, heat-treated, and tested under the precipitation conditions of phosphate ester hydraulic fluid with a variety of conditions. 23 full factorial designs have been applied to evaluate the significance of factors that affect the wear loss of the specimen, specifically, the load, velocity, and temperature. The significance evaluation was performed on the main effects and two-way interactions for wear loss based on the experiment results, and the mathematical equations between the wear loss and the three factors were derived from the analysis results.

• The Research Journal of the Costume Culture
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• v.22 no.5
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• pp.712-727
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• 2014

Dahoejangs in the Joseon Dynasty were craftsmen who belonged in the Gyeonggongjang in Hansung government office. Out of 2,841 craftsmen who specialized in 129 types of work, 1 of them were Dahoejangs. Dahoejangs were craftsmen who made cords. However it was not passed down and currently Maedeupjangs are making cords and making Maedeup with the cords they have made. In the Uigwes the composition of Dahoejangs number and types of tools used in creating good for ceremonies are indicated. This study has found records of Dahoejangs from 50 Uigwes. The tools used were indicated as Haesagee, Hapsagee, Hapseongee, Yeonsagee, Sangsagee, Dahoegee, Yungjapan and some others. Haesagee is a tool that winds thread from a skein to a spool. Hapsagee is a tool that combines more than two yarns together. Hapseon is for combining thicker threads. Yeosagee is not a process of scouring for refining, but is assumed to be a tool to twisting yarn. There are no information left about the shape or working methods of Sangsagee but it is considered to be a tool for doubling several threads together. Based on the existing artifacts and painting of Dahoe, it is assumed that threads were woven on usually a round plate or bowl. Youngjapan is considered to be a tool for making tassels. This shows that Dahoejangs made tassels and it was completely separate from making Maedeups. There, it is evident that Dahoejangs made cords as well as tassels but the work of Maedeupjang were constricted to only making Maedeup with the cords given to them.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.513-520
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• 2004

A steady-state/transient performance simulation model was newly developed for the propulsion system of the CRW (Canard Rotor Wing) type UAV (Unmanned Aerial Vehicle) during flight mode transition. The CRW type UAV has a new concept RPV (Remotely Piloted Vehicle) which can fly at two flight modes such as the take-off/landing and low speed forward flight mode using the rotary wing driven by engine bypass exhaust gas and the high speed forward flight mode using the stopped wing and main engine thrust. The propulsion system of the CRW type UAV consists of the main engine system and the duct system. The flight vehicle may generally select a proper type and specific engine with acceptable thrust level to meet the flight mission in the propulsion system design phase. In this study, a turbojet engine with one spool was selected by decision of the vehicle system designer, and the duct system is composed of main duct, rotor duct, master valve, rotor tip-jet nozzles, and variable area main nozzle. In order to establish the safe flight mode transition region of the propulsion system, steady-state and transient performance simulation should be needed. Using this simulation model, the optimal fuel flow schedules were obtained to keep the proper surge margin and the turbine inlet temperature limitation through steady-state and transient performance estimation. Furthermore, these analysis results will be used to the control optimization of the propulsion system, later. In the transient performance model, ICV (Inter-Component Volume) model was used. The performance analysis using the developed models was performed at various flight conditions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the turbine inlet temperature overshoot limitation as well as the compressor surge margin. Because the engine performance simulation results without the duct system were well agreed with the engine manufacturer's data and the analysis results using a commercial program, it was confirmed that the validity of the proposed performance model was verified. However, the propulsion system performance model including the duct system will be compared with experimental measuring data, later.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.83-94
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• 2000

A systematic humidity correction technique that can be used for any type of engine control mode is developed to predict the variation of engine performance due to inlet humidity. Limitation of conventional method is rot identified and then, a new method is proposed to take into account the humidity effects on each engine component characteristics and to find the variation of equilibrium running point through a re-match process between the components with a given engine control variable depending on the humidity of inlet. Comparisons are made between two methods for a single spool gas turbine engine, and it was found that the conventional method leads to invalid correction when a physical variable such as rotational speed is controlled for engine operation in humid environment. It was also found that the accuracy of the conventional method depends on the engine control mode and the engine configuration whereas the proposed method can be used for any type of engine control mode and engine configuration.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.30-37
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• 2004

This thesis develops a fuzzy-PID control algorithm for control the filament winding tension. It is developed by applying classical PID control technique to a fuzzy logic controller. It is composed of a fuzzy-PI controller and a fuzzy-D controller. The fuzzy-PI controller uses error and integrated error as inputs, and the fuzzy-D controller uses derivative of error as input. The fuzzy-PI controller uses Takagi-Sugeno fuzzy inference system, and the fuzzy-D controller uses Mamdani fuzzy inference system. The fuzzy rule base for the fuzzy-PI controller is designed using 19 rules, and the fuzzy rule base for the fuzzy-D controller is designed using 5 rules. A test-bed is set-up for verifying the effectiveness of the developing control algorithm in control the filament winding tension. It is composed of a mandrel, a carriage, a force sensor, a driving roller, nip rollers, a creel, and a real-time control system. Nip rollers apply a vertical force to a filament, and the driving roller drives it. The real-time control system is developed by using MATLAB/xPC Target. First, experiments for showing the inherent problems of an open-loop control scheme in a filament winding are performed. Then, experiments for showing the robustness of the developing fuzzy-PID control algorithm are performed under various working conditions occurring in a filament winding such as mandrel rotating speed change, carriage traversing, spool radius change, and reference input change.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.219-224
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• 2012

In this work, a steady-state performance modeling and off-design performance analysis of the 2-spool separate jet turbofan engine named BR715-56 which is a power plant for the narrow body commercial aircraft is carried out for engine performance behaviors investigation and condition monitoring using a commercial code MATLAB/SIMULINK. Firstly, the engine component maps of fan, high pressure compressor, high pressure turbine and low pressure turbine are generated from similar component maps using the scaling method, and then the off-design performance simulation model is constructed by the mass flow matching and the work matching between components. The model is developed using SIMULINK, which has advantages of easy steady-stare and dynamic modelling and user friendly interface function. It is found that the off-design performance analysis results using the proposed model are well agreed with the performance analysis results by GASTURB at various operating conditions.