• Title/Summary/Keyword: Stability of course

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A Study on the Manoeuvrability of KVLCC2 in Shallow Water by Free Running Model Test (자유항주모형시험을 이용한 KVLCC2 선형의 천수영역에서의 조종성능에 관한 연구)

  • Yun, Kunhang;Yeo, Dong Jin;Park, Byoungjae
    • Journal of the Society of Naval Architects of Korea
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    • v.52 no.6
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    • pp.494-500
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    • 2015
  • It has been reported that a ship sailing in shallow water possesses better straight-line stability due to the change of fluid flow around the ship. This tendency affects manoeuvring characteristics of the ship. To investigate this phenomenon, indoor free running model test(FRMT) on KVLCC2 was carried out in three water depth conditions(H/T = 1.2, 1.5 & 2.0). Turning circle tests(± 35° ) and zigzag tests(± 20° /5° and ± 20° /10° ) were conducted with newly developed indoor FRMT system, and the manoeuvring results were compared with test results from other institutes. As the water depth decreased, the yaw rate of the ship decreased, and the distances of circular trajectories at the same heading angle increased in the turning circle tests. The first overshoot angles of the zigzag tests decreased. From both tests, the time for course change increased as the water depth decreased. These manoeuvring characteristics show that KVLCC2 in shallow water becomes more stable in terms of straight-line stability.

An Experimental Study on the Vertical Motion of a High-Speed Planing Craft in Regular Following Waves (선미 규칙파 중 고속 활주선의 연직면 운동에 대한 실험적 연구)

  • Kim, Dong-Jin;Rhee, Key-Pyo;You, Young-Jun;Park, Han-Sol
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.4
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    • pp.496-507
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    • 2010
  • It is well known that when a high-speed planing craft travels in following seas it experiences long-periodic motions due to low encounter frequency, and it often loses its course keeping stability. Therefore, it is necessary to study the sea-keeping performance and stability of it in the following seas. In this paper, the vertical motions of a planing craft were measured in following regular waves, and the test results were compared with the theoretical results. In the case of the same encounter frequency, non-dimensionalized motion amplitudes become larger as Froude number is higher, and non-dimensionalized motion amplitudes in head waves are larger than those in following waves. The mean values of the motions in following waves are similar to the running attitudes of a craft in calm water at the same Froude number.

Stability and Formation of the Liposome with Phospholipid Base (Phospholipid의 Gelation에 의한 Liposome 형성과 안정성)

  • Kim, In-Young;Ji, Hong-Keun;Hong, Chang-Yong;Kang, Sam-Woo
    • Journal of the Korean Applied Science and Technology
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    • v.13 no.1
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    • pp.11-19
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    • 1996
  • The liposomes have been developed in many drugs and cosmetics fields. The liposomes prepared with main compounds of the intercellular lipids and lecithin. Amphiphile nonionic surfactants used for (PEG) n-sitosterol(n=5), diethanolamine cetylphosphate. The effect of gelation for liposomes have been on swelling reaction which have been mixed phospholipid with polyol-group at the high temperature. There were very good encapsulated properties of the active ingredients whether hydrophilic-group(magnesium ascorbyl phosphate, allantoin, sodium hyaluronate) and hydrophobic-group(vitamin-E acetate, vitamin-A palmitate). Optimum condition of liposomes were passed five times in the microfluidizer(700bar), wetting reaction temperature was at $95{\pm}5^{\circ}C$ for a hours. Particle size distribution of the vesicles should be within range 50-560nm(mean 200nm). The stability of liposomes for the course of time was stabilized for six months at $45^{\circ}C$. Application of the cosmetic was prepared moisturizing cream with liposomes of the phospholipid base.

Dispersion Stability Determination of Saengshik Beverage by Optical Methods (광학적 방법에 의한 생식음료의 분산 안정성 측정)

  • Lee, Ju-Yeon;Mok, Chulkyoon
    • Food Engineering Progress
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    • v.14 no.1
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    • pp.41-48
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    • 2010
  • An optical method was introduced to investigate the dispersion stability of Saengshik beverages (SB) containing 3.7-11.7% Saengshik powder (SP). Time course changes in backscattering light flux (BSLF) from SB were monitored by a Turbiscan. BSLF in the bottom and top layers of SB increased by forming sediment and foam, respectively, while that in the middle layer decreased by clarifying. With SP levels, sedimentation in SB was retarded, but the height of total sedimentation layer was increased. A logarithmic model was developed to fit to the changes in BSLF with time, showing determination coefficients of 0.979-0.988. The levels of SP in SB influenced the migration speed of the clarification front as well as the numbers of separated layers; 2 layers in SB containing 3.7% SP, 3 in 5.7-9.7%, and 4 in 11.7%. Formation of clear layers started after 17-29 min and continued for 22-53 min. The clarification was retarded most in SB containing 7.7% SP, indicating the most stable SP level for the SB preparation.

Locomotion of Dog-like Quadruped Robots: Walk and Trot (견형 4족 로봇의 위치 이동: 걷기 및 속보)

  • Lim, Seung-Chul;Kim, Kwang-Han
    • Journal of the Korea Society for Simulation
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    • v.20 no.1
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    • pp.51-59
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    • 2011
  • This paper is concerned with locomotion of dog-like quadruped robots that can adapt to various terrains, mainly dealing with implementation methods and characteristics of static and dynamic gaits. To this end, a 12-DOF robot is built in house, motional trajectories of its body and feet are generated mimicking biological life, and the corresponding leg joint angles are analytically obtained by inverse kinematics. Such joint angle data are then applied to the robot's ADAMS model for computer simulations so that the planned walk and trot gaits are both confirmed dynamically stable. However, contrary to the simulation results, previous trot patterns showed unstable behavior during experiments. This problem led us to analyze the reason, and in the course we discovered the importance of maximally utilizing the concept of WSM rather than ZMP and therefore reducing the gait period to secure the stability of dynamic gaits such as trot.

Development of Satisfaction Evaluation Items for Degree-linked High Skills Meister Courses using the Delphi Method (Delphi 기법을 활용한 학위연계형 고숙련마이스터 과정의 만족도 평가 문항 개발)

  • Kim, Seung-Hee
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.5
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    • pp.163-173
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    • 2020
  • In this study, on-site corporate instructors participated as student-cum-workers in a degree-linked high skills Meister course to improve job competency and practical ability as proposed in the Work-Study Career Vision. Evaluation questions were then developed and their validity was verified by assessing satisfaction related to expected goals in enhancing advanced training guidance and competency as an evaluator. Satisfaction assessment was conducted based on training preparation, training implementation, training effectiveness and training administration. The Delphi Method was adopted and a total of 48 items were developed in 6 categories under 4 main areas. There were 7 evaluation items on the satisfaction of training course development under training preparation, 21 evaluation items related to the satisfaction of Off-JT and OJT courses under training implementation, 16 evaluation items related to the satisfaction of increased competency as an on-site corporate instructor and the satisfaction of enhanced practical skills and skills application at work under training effectiveness, as well as 6 evaluation items to assess satisfaction with administrative support under training administration. The final conformity assessment was conducted based on the stability, content validity ratio, consensus and convergence indicators of the developed items. Results of this study do not only apply to quality management of the high skills Meister course which is being promoted as a pilot project for work-study programs, but also serves as a rationale that may be considered as a basic research tool in the collection of various opinions to derive overall system improvement factors for the work-study high skills Meister course.

A Study on the Vocational Culture Conflicts and Vocational Adaptation of North Korean Defectors (북한이탈주민의 직업문화충돌과 직업적응에 관한 연구)

  • Cho, In-Soo;Son, Min-Jeong;Choi, Jeong-Eun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.1
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    • pp.354-372
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    • 2020
  • This study analyzed how North Korean defectors recognized and overcame conflict in the South Korean job culture during the course of entering and settling into South Korea, and the association between their old career and adaptation within their new careers. The study selected 13 employed participants who entered South Korea more than five years ago and experienced working. Interviews were conducted over the course of five years. The topics were analyzed after performing interviews 60 to 120 minutes long by recording and transcribing the recordings and using semi-structured questionnaires for the 13 people. The results reflected the job environment in North Korea, their career background, factors for a successful new life, their constant efforts for employment, the difficult adaption to South Korean life, pursuing job stability, accepting South Korean culture, and career compromises. The results of this study are as follows. First, they undergo difficulty in the course of selecting jobs due to the converted environment from passivity to autonomy. Second, they cannot use their previous job history and they complained about prejudice and the lack of job information. Third, major problems included their lack of adaptability, stress, and loss of economic power. The study suggests that these North Korean defectors undergo an integrated course of cultural learning. Fourth, they were hardly able to adapt. Fifth, they tried to overcome conflicts of job culture according to their personal characteristics.

An Applicability of Bioregional Planning Theory (생물지역계획 이론의 적용가능성)

  • 장병관
    • Journal of the Korean Institute of Landscape Architecture
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    • v.28 no.4
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    • pp.54-65
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    • 2000
  • The purpose of this paper is to examine the concept, general framework, planning process of bioregion, and bioregional impacts on landscape planning of future and to discuss the application possibility of landscape planning. Bioregionalism is defined in the course of following: knowing the land, learning the lore, developing the potential, liberating the self. Bioregional paradigm was composed of policy system insisted on diversity and decentralization based on region and community, sustainable economy structure focused on conservation and stability, and society structure through cooperation with common consciousness in the community. A general bioregional framework was organized to be able to achieve a sustainable future with interaction for humans being, other living things, and important earth life system. Bioregional mapping should be able to explain three important aspects about how localised and sustainable cultures would exist: to define the external boundaries, to describe forces of energy, and give a hint for th productive capability. In conclusion, according to the result of reviewing the total environmental planning, bioregional paradigm, examples of projects, technique of bioregional mapping, and actions of Nongovernmental Organizations(NGOs). this study is helpful to show an applicability of bioregional planning theory in Korea

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Development of Novel Polymeric Sunscreen Agent

  • Hyo-Joong Kim;Hye
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.22 no.2
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    • pp.89-98
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    • 1996
  • A novel polymeric sunscreen agent was developed. It was prepared by the coupling reaction of 2-ethylhexyl 4-hydroxycinnamate with poly vinylbenzyl chloride(PVBC, average MW 6,500). In this reaction the reactivity was mostly affected by catalyst. In the absence of catalyst the yield was approximately 55% and in the presence of tetrabutylammonium bromide the yield was about 65%, but in the presence of tetrabutylammonium iodide the yield was 100% to give a average molecular weight 20,000 polymeric sunscreen agent. There were no side reactions, and its structure and purity were confirmed by various analytical methods, such as NMR, IR, and so on. UV radiation absorption efficiency is more than 70% compared with that of octyl methoxycinnamate. The solubility in polar oil, for example C12-15 alkylbenzoate and caprylic/capric triglyceride, is more than 50%. It showed high stability in the time course of test including acceleration test. This polymer is safe to skin because of poor permeability to skin, no side products in the process of preparing, and easy elimination of excess starting materials.

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A Comparative Study on $CO_2$ Amount of Construction-Materials (건축 구조 재료별 $CO_2$ 발생량 비교 연구)

  • Oh, Myoung-Ho;Han, Yong-Sup;Cho, Kwang-Moon
    • Proceedings of the KAIS Fall Conference
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    • 2007.11a
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    • pp.375-377
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    • 2007
  • The purpose of this study was to investigate total $CO_2$ amount of steel and reinforced concrete construction, and compare and analyze $CO_2$ amount on construction-material. And then it was studied about new element that environment compatibility of architecture structure design based on paradigm of environment age. Architecture action should have proceeded course that reduce burden of the earth environment in relation between architecture and environment and increase contact of human and nature. As environment compatibility development is emphasized with architecture development, architecture structure design give improvement of one important element that environment compatibility except stability, function, economy and necessary propriety of environment compatability of construction design.

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