• 한국해양공학회지
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• 제22권6호
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• pp.75-82
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• 2008

Flame bending has been extensively used in the shipbuilding industry for hull plate forming In flame bending it is difficult to obtain the desired shape because the residual deformation dependson the complex temperature distribution and the thermal plastic strain. Mechanical bending such as reconfigurable press forming multi-point press forming or die-less forming has been found to improve the automation of hull plateforming because it can more accurately control the desired shape than line heating. Multi-point forming is a process in which external forces are used to form metal work-pieces. Therefore it can be a flexible and efficient forming technique. This paper presents an optimal approach to determining the press-stroke for multi-point press forming of curved shapes. An integrated configuration of Finite element analysis (FEA) and spring-back compensation algorithm is developed to calculate the strokes of the multi-point press. Not only spring-back is modeled by elastic plastic shell elements but also an iterative algorithm to compensate the spring-back is applied to adjust the amount of pressing stroke. An iterative displacement adjustment (IDA) method is applied by integration of the FEA procedure and the spring-back compensation work. Shape deviation between the desired surface and deform￡d plate is minimized by the IDA algorithm.

• 한국세라믹학회지
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• 제41권5호
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• pp.353-358
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• 2004

Spray drying is a unique drying process for powder production. Spray dried product must be free-flowing in order to fill the pressing dies rapidly, especially in the ceramic production. The important powder characteristics are; the particle size distribu-tion and moisture content of the finished product that can be estimated and adjusted by the spray dryer operation, within limits, through regulation of atomizer and drying conditions. In order to estimate the moisture content of the resultant dried product, we modeled the control system of the drying process using two different Artificial Neural Network (ANN) approaches, namely the Back-Propagation Multiplayer Perceptron (BPMLP) algorithm and the Radial Basis Function (RBF) network. It was found out that the performance of both of the artificial neural network models were quite significant and the total testing error for the 100 data was 0.8 and 0.7 for the BPMLP algorithm and the RBF network respectively.

• 소성∙가공
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• 제19권4호
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• pp.203-209
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• 2010

In the hot press forming process (HPF), a martensitic structure is obtained by controlling the cooling rate when cooling a boron sheet that is heated up to over $900^{\circ}C$. The HPF process has various advantages such as the improvement in formability and material properties and minimal spring back of the deformed materials. The factors related to the cooling rate depend on the heat transfer characteristics between heated materials and dies. Therefore, in this study, the cooling rate is controlled by adjusting the heat transfer coefficient of the material at the pressing process. And, the mechanical properties and microstructure of the deformed material is demonstrated during the HPF process where cold dies are used to form the heated steel plate. This is achieved by varying the major forming conditions that control the cooling rate regarded as the most important process parameter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1887-1889
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• 2005

To measure the mechanical and structural properties of semiconducting materials in power cable, we have investigated the stress-strain and fractural structure of semiconducting materials showed by changing the content of carbon black. Those were made as sheets after pressing for 20 minutes at $180[^{\circ}C]$ with a pressure of $200[kg/cm^2]$. The contents of conductive carbon black were 20, 30 and 40(wt%), respectively. The stress-strain experiment was measured by TENSOMETER 2000. The SEM experiment was measured by JSM-6400. From above experimental result, Strain was decreased, while stress was increased according to increment of carbon black content. EEA among resins was best the dispersion of carbon back in base resin from SEM measurement.

• 제어로봇시스템학회논문지
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• 제5권6호
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• pp.724-733
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• 1999

An effective method of system modeling and dynamic scheduling for the back-end line of semiconductor manufacturing is proposed. The virtual factory, describing semiconductor manufacturing line, is designed in detail, and then a Petri net model simulator is developed for operation and control of the modular cells of the virtual factory. The petri net model is a colored timed Petri nets (CTPNs). The simulator will be utilized to analyze and evaluate various dynamic status and operatons of manufacturing environments. The dynamic schedulaer has a hierarchical structure with the higher for planning level and the lower for dynamic scheduling level. The genetic algorithm is applied to extract optimal conditions of the scheduling algorithm. The proposed dynamic scheduling is able to realize the semiconductor manufacturing environments for the diversity of products, the variety of orders by many customers, the flexibility of order change by changing market conditions, the complexity of manufacturing processes, and the uncertainty of manufacturing resources. The proposed method of dynamic scheduling is more effective and useful in dealing with such recent pressing requirements including on-time delivery, quick response, and flexibility.

• Journal of the Korean Wood Science and Technology
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• 제39권2호
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• pp.148-155
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• 2011

Thermal treatment techniques are used for modifying wood and wood-based materials to improve dimensional stability and hygroscopicity. This study investigated the effects of press pressure and temperature on density, vertical density profile, thickness swelling and surface hardness of eucalyptus wood boards. The experimental wood boards were prepared from Turkish River Gum ($Eucalyptus$ $camaldulensis$ Dehn.). The surface hardness value increased with increasing press pressure in the treated groups. The application of a higher pressure at the same temperature level increased the amount of swelling of wood. It means that it is not needed for application of higher pressure to enhance the dimensional stability of wood. It is expected that it is possible to produce increased hardness, dimensional stability and durability by application of hot pressing treatment. This research showed that different press pressure and temperature values should be used to improve the performance properties of eucalyptus wood so that the end-use of the wood materials could be expanded.

• 한국기계가공학회지
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• 제7권3호
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• pp.75-80
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• 2008

The progressive die performs a work of sheet metal processes with a piercing, notching, embossing, bending, drawing, cut-off etc. in many kinds of pressing. Now a days, these processes have been evaluated as a advanced tooling method to increase the productivity and high quality assurance. The first step analyzing of die design is production part review, then the arrangement drawing of product design and strip process layout design should be done as a next steps with a FEM simulation for its problem solution. After upper procedure were peformed, it was started to make the die, then tryout and its revision of the die and product quality, safety, productivity etc. were done continually. For the all of these process, we mobilized the theory and practice of sheet metal forming, die structure, the function and activity of die components, and the others of die machining, die material, heat treatment and know‐how so on. In this study the features of representative are production part analyzing through the FEM simulation of bending area with a considering spring back problem by DEFORM.

• 정보과학회 논문지
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• 제44권6호
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• pp.595-600
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• 2017

안드로이드 어플리케이션은 하나 이상의 컴포넌트로 구성되어 있으며 컴포넌트들은 인텐트를 통해 동일 어플리케이션 또는 다른 어플리케이션의 컴포넌트를 호출하여 사용할 수 있다. 이와 같은 컴포넌트 상호작용을 악용한 BroadcastTheft, Activity Hijacking, Intent Spoofing 등과 같은 문제점들을 검사하기 위해서는 다양한 상호작용 시나리오를 생성하여 테스팅을 진행하여야 한다. 하지만 기존 상호작용 테스트 시나리오 생성 연구에서는 각 액티비티 설정에 따라 이전화면으로의 이동시 재실행 순서가 달라지는 안드로이드 특성을 고려하지 않아 실행 불가능한 테스트 시나리오들이 포함될 수 있는 문제점이 있다. 본 논문에서는 액티비티 스택 정보를 이용하여 상호작용 테스트 시나리오에서 실제 실행되지 않는 경로를 제거하는 방법을 제안한다.

• Child Health Nursing Research
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• 제13권2호
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• pp.182-190
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• 2007

Purposes: The purposes of this study were to identify the level of knowledge of good posture and postural habits among elementary school children and to identify the relationship between knowledge of good posture and postural habits. Method: A descriptive correlational study was conducted. The participants were 507 elementary school children in Jangheung County. Data were collected using self-administered questionnaires. Descriptive statistics, t-test, ANOVA, and correlation were used for data analysis. Results: The percentage of correct answer for the knowledge test was 65.83%. Postural habits were not good. Although the strength of correlation was low, there is a statistically significant positive correlation between knowledge and postural habits. Not only school health nurses but also class teachers and parents played important roles in spinal health education. Educational needs for spinal health are high. Conclusion: Although more research in this area is warranted, there is a pressing need for interventions aimed at developing healthy habits that promote postural hygiene among elementary school children. Development and evaluation of back education programs in elementary school is necessary.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권10호
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• pp.443-448
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• 2005

To measure modulus, damping properties and smoothness of semiconducting materials in power cable, we have investigated those of semiconducting materials showed by changing the content of carbon black. Then they were produced as sheets after pressing for 20 minutes at 180[$^{\circ}C$] with a pressure of 200[kg/cm$^{2}$]. The content of conductive carbon black was the variable, and their contents were 20, 30 and 40[wt$\%$], respectively. The modulus and tans were measured by DMA 2980. The ranges of measurement temperature were from -50[$^{\circ}C$] to 100[$^{\circ}C$] and measurement frequency was 1[Hz3. The modulus of specimens was increased according to a increment of a carbon black content. And modulus was rapidly decreased at the glass transition temperature. The tans of specimens was decreased according to a increment of a carbon black content. The smoothness was measured by JSM-6400. EEA resin from SEM measurement was best the dispersion of carbon back in base resin.