• Title/Summary/Keyword: task-dynamic

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A Numerical Study on Ventilation Characteristics of Factors Affecting Leakages in Hydrogen Ventilation (누출 수소 환기에 영향을 미치는 요인별 환기 특성에 관한 수치해석적 연구)

  • Lee, Chang-Yong;Cho, Dae-Hwan
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.4
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    • pp.610-619
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    • 2022
  • Hydrogen is emerging as an alternative fuel for eco-friendly ships because it reacts with oxygen to produce electrical energy and only water as a by-product. However, unlike regular fossil fuels, hydrogen has a material with a high risk of explosion due to its low ignition point and high flammability range. In order to safely use hydrogen in ships, it is an essential task to study the flow characteristics of hydrogen leakage and diffusion need to be studied. In this study, a numerical analysis was performed on the effect of leakage, ventilation, etc. on ventilation performance when hydrogen leaks in an enclosed space such as inside a ship. ANSYS CFX ver 18.1, a commercial CFD software, was used for numerical analysis. The leakage rate was changed to 1 q, 2 q, and 3 q at 1 q = 1 g/s, the ventilation rate was changed to 1 Q, 2 Q and 3 Q at 1 Q = 0.91 m/s, and the ventilation method was changed to type I, type II, type III to analyze the ventilation performance was analyzed. As the amount of leakage increased from 1 q to 3 q, the HMF in the storage room was about 2.4 to 3.0 times higher. Furthermore, the amount of ventilation to reduce the risk of explosion should be at least 2 Q, and it was established that type III was the most suitable method for the formation of negative pressure inside the hydrogen tank storage room.

A Study on Optimized Artificial Neural Network Model for the Prediction of Bearing Capacity of Driven Piles (항타말뚝의 지지력 예측을 위한 최적의 인공신경망모델에 관한 연구)

  • Park Hyun-Il;Seok Jeong-Woo;Hwang Dae-Jin;Cho Chun-Whan
    • Journal of the Korean Geotechnical Society
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    • v.22 no.6
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    • pp.15-26
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    • 2006
  • Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms are not yet entirely understood. The prediction of bearing capacity is a difficult task, because large numbers of factors affect the capacity and also have complex relationship one another. Therefore, it is extremely difficult to search the essential factors among many factors, which are related with ground condition, pile type, driving condition and others, and then appropriately consider complicated relationship among the searched factors. The present paper describes the application of Artificial Neural Network (ANN) in predicting the capacity including its components at the tip and along the shaft from dynamic load test of the driven piles. Firstly, the effect of each factor on the value of bearing capacity is investigated on the basis of sensitivity analysis using ANN modeling. Secondly, the authors use the design methodology composed of ANN and genetic algorithm (GA) to find optimal neural network model to predict the bearing capacity. The authors allow this methodology to find the appropriate combination of input parameters, the number of hidden units and the transfer structure among the input, the hidden and the out layers. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the bearing capacity of driven piles.

The Properties of Beam Intensity Scanner (BInS) for Dose Verification in Intensity Modulated Radiation Therapy (방사선 세기 조절 치료에서 선량을 규명하는 데 사용된 BlnS System의 특성)

  • 박영우;박광열;박경란;권오현;이명희;이병용;지영훈;김근묵
    • Progress in Medical Physics
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    • v.15 no.1
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    • pp.1-8
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    • 2004
  • Patient dose verification is one of the most Important responsibilities of the physician in the treatment delivery of radiation therapy. For the task, it is necessary to use an accurate dosimeter that can verify the patient dose profile, and it is also necessary to determine the physical characteristics of beams used in intensity modulated radiation therapy (IMRT) The Beam Intensity Scanner (BInS) System is presented for the dosimetric verification of the two dimensional photon beam. The BInS has a scintillator, made of phosphor Terbium-doped Gadolinium Oxysulphide (Gd$_2$O$_2$S:Tb), to produce fluorescence from the irradiation of photon and electron beams. These fluoroscopic signals are collected and digitized by a digital video camera (DVC) and then processed by custom made software to express the relative dose profile in a 3 dimensional (3D) plot. As an application of the BInS, measurements related to IWRT are made and presented in this work. Using a static multileaf collimator (SMLC) technique, the intensity modulated beam (IMB) is delivered via a sequence of static portals made by controlled leaves. Thus, when static subfields are generated by a sequence of abutting portals, the penumbras and scattered photons of the delivered beams overlap in abutting field regions and this results in the creation of “hot spots”. Using the BInS, inter-step “hot spots” inherent in SMLC are measured and an empirical method to remove them is proposed. Another major MLC technique in IMRT, the dynamic multileaf collimator (DMLC) technique, has different characteristics from SMLC due to a different leaf operation mechanism during the irradiation of photon and electron beams. By using the BInS, the actual delivered doses by SMLC and DMLC techniques are measured and compared. Even if the planned dose to a target volume is equal in our experimental setting, the actual delivered dose by DMLC technique is measured to be larger by 14.8% than that by SMLC, and this is due to scattered photons and contaminant electrons at d$_{max}$.

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Essay on Form and Function Design (디자인의 형태와 기능에 관한 연구)

  • 이재국
    • Archives of design research
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    • v.2 no.1
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    • pp.63-97
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    • 1989
  • There is nothing more important than the form and function in design, because every design product can be done on the basis of them. Form and Function are already existed before the word of design has been appeared and all the natural and man-made things' basic organization is based on their organic relations. The organic relations is the source of vitality which identifies the subsistance of all the objects and the evolution of living creatures has been changed their appearances by the natural law and order. Design is no exception. Design is a man-made organic thing which is developed its own way according to the purposed aim and given situations. If so, what is the ultimate goal of design. It is without saying that the goal is to make every effort to contribute to the -human beings most desirable life by the designer who is devoting himself to their convenience and well-being. Therefore, the designer can be called the man of rich life practitioner. This word implies a lot of meanings since the essence of design is improving the guality of life by the man-made things which are created by the designer. Also, the things are existed through the relations between form and function, and the things can keep their value when they are answered to the right purpose. In design, thus, it is to be a main concern how to create valuable things and to use them in the right way, and the subject of study is focused on the designer's outlook of value and uk relations between form and function. Christopher Alexander mentioned the importance of form as follows. The ultimate object of design is form. Every design problem begins with an effort to achieve fittness between the form and its context. The form is the solution to the problem: the context defmes the problem. In other words, when we speak of design, the real object of discussion is not form alone, but the ensemble comprising the form and its context. Good fit is a desirable property of this ensemble which relates to some particular division of the ensemble into form and context. Max Bill mainatined how important form is in design. Form represents a self-contained concept, and its embodiment in an object results in that object becoming a work of art. Futhermore, this explains why we use form so freguently in a comparative sense for determining whether one thing is less or more beautiful than another, and why the ideal of absolute beauty is always the standard by which we appraise form, and through form, art itself. Hence form has became synonymous with beauty. On the other hand, Laszlo Moholy-Nagy stated the importance of function as follows. Function means the task an object is designed to fulfill the task instrument is shaping the form. Unfortunately, this principle was not appreciated at the same time but through the endeavors of Frank Lloyd Wright and of the Bauhaus group and its many collegues in Europe, the idea of functionalism became the keynote of the twenites. Functionalism soon became a cheap slogan, however, and its original meaning blurred. It is neccessary to reexamine it in the light of present circumstances. Charles William Eliot expressed his idea on the relations between function and beauty. Beauty often results chiefly from fittness: indeed it is easy to manitain that nothing is fair except what is fit its uses or functions. If the function of the product of a machine be useful and valuable, an the machine be eminently fit for its function, it conspicuously has the beauty of fittness. A locomotive or a steamship has the same sort of beauty, derived from the supreme fittness for its function. As functions vary, so will those beauty..vary. However, it is impossible to study form and function in separate beings. Function can't be existed without form, and without function, form is nothing. In other words, form is a function's container, and function is content in form. It can be said that, therefore, the form and function are indispensable and commensal individuals which have coetemal relations. From the different point of view, sometimes, one is more emphasized than the other, but in this case, the logic is only accepted on the assumption of recognizing the importance of the other's entity. The fact can be proved what Frank Hoyd wright said that form and function are one. In spite of that, the form and function should be considered as independent indivisuals, because they are too important to be treated just as the simple single one. Form and function have flexible properties to the context. In other words, the context plays a role as the barometer to define the form and function, also which implies every meaning of surroun'||'&'||'not;dings. Thus, design is formed under the influence of situations. Situations are dynamic, like the design process itself, in which fixed focus can be cripping. Moreover, situations control over making the good design. Judging from the respect, I defined the good design in my thesis An Analytic Research on Desigh Ethic, "good design is to solve the problem by the most proper way in the situations." Situations are changeable, and so is design. There is no progress without change, but change is not neccessarily progress. It is highly desirable that there changes be beneficial to mankind. Our main problem is to be able to discriminate between that which should be discarded and that which should be kept, built upon, and improved. Form and Function are no exception. The practical function gives birth to the inevitable form and the $$\mu$ti-classified function is delivered to the varieties of form. All of these are depended upon changeable situations. That is precisely the situations of "situation de'||'&'||'not;sign", the concept of moving from the design of things to the design of the circumstances in which things are used. From this point of view, the core of form and function is depended upon how the designer can manage it efficiently in given situations. That is to say that the creativity designer plays an important role to fulfill the purpose. Generally speaking, creativity is the organization of a concept in response to a human need-a solution that is both satisfying and innovative. In order to meet human needs, creative design activities require a special intuitive insight which is set into motion by purposeful imagination. Therefore, creativity is the most essential quality of every designer. In addition, designers share with other creative people a compulsive ingenuity and a passion for imaginative solutions which will meet their criteria for excellence. Ultimately, it is said that the form and function is the matter which belongs to the desire of creative designers who constantly try to bring new thing into being to create new things. In accordance with that the main puppose of this thesis is to catch every meaning of the form and function and to close analyze their relations for the promotion of understanding and devising practical application to gradual progression in design. The thesis is composed of four parts: Introduction, Form, Function and Conclusion. Introduction, the purpose and background of the research are presented. In Chapter I, orgin of form, perception of form, and classification of form are studied. In Chapter II, generation of function, development of function, and diversification of function are considered. Conclusion, some concluding words are mentioned.ioned.

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A Study on the Effects of an Increase in the Height of Ship's Accommodation Area on Safe Evacuation in Emergency Situation (선박 거주구역의 높이가 피난안전에 미치는 영향에 대한 연구)

  • Kim, Won-Ouk;Kim, Jong-Su
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.17 no.1
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    • pp.69-73
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    • 2011
  • Unlike land fires, Fires on board a ship are not likely to be extinguished by skilled human resources using a variety of fire fighting equipments, but have to be brought under control on board a ship itself despite of difficult task. There are more cases of deaths from suffocation by smoke than from an increased temperature by heat in fires on board ships, because crew fail to secure a sufficient visibility range enough to escape from the scene of a fire or to leave the ship as early as possible. On the assumption that the height of ship's accommodation area increases from 2.0m to 2.3m comparable to the height of apartments on the ground in Korea, behaviors of fire smokes between the cases of 2.0m and 2.3m heights were compared and analyzed. Based on the blue print of the existing Training Ship "Hanbada", a new blueprint with the 30 cm height adjustment was additionally created. FDS (Fire Dynamic Simulator), which was created by the NIST in the United States and is the most widely distributed simulator for fires, was used to conduct a simulation and predict results. The results of simulation on the basis of temperature of $60^{\circ}C$ showed a safe evacuation period of time at the position 10m apart from the scene of a fire to increase by 55.8 seconds, when the height of ship's accommodation area increased from 2.0m to 2.3m. The results of simulation on the basis of visibility range of 6m showed the safe evacuation periods of time at the positions 10m, 20m and 30m apart from the scene of a fire to increase by 27.1 seconds, 109.2 seconds and 73.3 seconds, respectively, as the height of ship's accommodation area increased from 2.0m to 2.3m. This means that crew can escape more safely from a scene of fires on board when the height of ship's accommodation area is increased and equal to the height of living room in a building on land.

The Development and Effectiveness of a PBL Based Career Education Program (PBL 기반 진로교육 프로그램의 개발 및 효과검증)

  • Lee, Hye-Suk;Kim, You-Me
    • The Korean Journal of Elementary Counseling
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    • v.8 no.1
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    • pp.33-50
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    • 2009
  • The purpose of this study was to develop a PBL-based career education program and to examine its effectiveness on school children's career maturity. It's specifically meant to prepare a career education program to assist students to get an accurate grip on their aptitude, interest and personality and explore various sorts of occupations in the course of solving authentic and contextual career-related problems. After children's developmental characteristics and needs were analyzed, task analysis was implemented, and the objectives were defined. And then the core of the program, PBL problems were developed, and the validity of the problems were verified Evaluation plans and tools were prepared to assess children's problem-solving process and presentation, and an online learning space was designed. The program that consisted of 10-minute 21 sessions was provided to fifth-grade elementary schoolers for eight weeks. The findings of the study were as follows: The experimental group that participated in the PBL-based career education program showed a more significant improvement than the control group that didn't in career attitude and three career attitude subfactors involving planness, disposition and compromise. And the former made a more significant progress than the latter in career ability and its subfactors including vocational comprehension, self-understanding and decision-making skills as well. As a result of making a content analysis to make up for the survey, the students reported that they were able to get an objective understanding of themselves and acquire diverse and profound knowledge on work and the business world in the middle of solving the given PBL problems related to different areas in group and giving a presentation. In conclusion, a PBL based career education program developed by this researcher encouraged the students to have an objective self-understanding, to have a dynamic interactive discussion with their group members. Therefore the program had a positive impact on boosting the career attitude and career ability of the elementary schoolers. The findings suggested that in the field of elementary career education, autonomous learning attitude and subjecthood are the crucial factors to stimulate school children to explore and create their own future.

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