• Polymer(Korea)
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• v.33 no.4
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• pp.377-383
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• 2009

Ionic polymer-metal composite (IPMC) actuator generates bending actuation via ion/water flux to the cathode side under an electric field. Polyelectrolytes in IPMC should possess high water-retention capability, proton conductivity, and Young's modulus. In this study. for endowing IPMCs with these properties, Nafion-alumina composite membranes containing $\alpha$- or $\gamma$-aluminas of $4{\sim}8$ wt% were prepared. Mechanical moduli of Nafion-alumina composite membranes were $7{\sim}3$ MPa higher than that of Nafion, with the slight decrease in proton conductivity. At DC 3 V. the actuation performance of the Nafion-$\alpha$-alumina (8 wt%)-IPMC was superior to that of the typical Nafion-IPMC. exhibiting 2.7 times the displacement with an enhanced blocking force. The enhanced actuation performance with the Nafion-$\alpha$-alumina composite membranes was attributed to the higher proton conductivity, the elevated ion/water flux, and the lower interfacial electric resistance of platinum electrodes and membrane, compared with those containing $\gamma$-alumina.

• Journal of Service Research and Studies
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• v.7 no.2
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• pp.1-16
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• 2017

The service that has been recognized as both a non-productive activity and auxiliary activity of manufacturing have become the driving force of the customers' demand with the 'service' itself. The service base is expanding and evolving rapidly. It is important to look at changes in service concepts to understand service systems. Because the service system itself has a cyclic nature based on the concept of service, it can help in the study and the "how" of service by looking at changing the system according to the evolution of the service concept. The ability to organize and utilize relationships is considered to be an important factor for managers in the service economy era. However, the attention of corporate is focused on their internal capabilities and they are familiar with external resources (knowledge and competence of customers). In this case study for each type of service, we analyzed the activities of interacting service providers-consumers in service relationship, and constructed a new service system model emphasizing intangible value and long-term outcome. This study is worth re-examining the role of customers in today's service economy era and actively utilizing a new service model for business performance.

• Journal of Families and Better Life
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• v.2 no.1
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• pp.131-150
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• 1984

The purpose of this study is to explore the family as an interaction system, concentrating on the mutual influences between communication and family development; (1) how Communication patterns affect family relationships, and (2) how relationships among family members affect communication. In order to do this Galvin, Brommel used the following frame work; family is a system in which communication regulates cohesion and adaptability by a flow of message patterns through a defined network of evolving interdependent relationships. A family system consists of members, the relationships among them, the family attributes, the members attributes and an environment in which family functions. Within the framework of common cultural communication patterns, each family has the capacity to develop its own communication code based on the experiences of individual members and the collective family experience. Most of us develop our communication skills within the family context learning both the general cultural language and the specific familial communication code. Communication may be viewed as a symbolic, transactional process as the process of creating and sharing meanings. To say that communication is a process implies a continuous interaction of an indefinite large numbers of variables with a concomitant,. continuous change in the values taken by these variables. Finally the process implies change, Family functions include the primary functions of cohesion and adaptability, and supporting functions of family images, themes, boundaries, and biosocial issues. The primary functions reveal concepts integrated family interaction and supporting function, along with those of cohesion and adaptability, give shape to family life. the characteristics of developed relationships of richness, uniqueness efficiency, substitutability, pacing , openness spontaneity, and evaluation are reflected in the verbal and nonverbal behaviors with which family members negotiated a set of common meanings and develop thier own unique message system. The message system is the major element of communication process and influences both the form and the content of thier relationship and in create and share meanings. Family systems need to provide order and predictability for thier members, specifically focusing on communication rules and the networks by which messages are transmitted. Most rules emerge as a result of multiful interactions. There are basic rules and rules about rules, or metarules. Perceiving the rules of family system is very difficult because often family members don't think about the basic rules, much less the metarules. Breaking the rule may result in the creation of a new set because the system may recalibrate itself to accept more variety of behavior. Families develop communication networks to deal with the general issue. Family adaptability may be seen through the degree of flexibility in forming and reforming networks and networks become a vital part of the decision- making process and relate to the power dynamics operating within the family. Networks also play an integral part in maintaining the roles and rules operating with the family system. Thus networks and rules have mutual influence. The family -of -origin issues influence all aspects of family communication and account for many of the communication patterns, rules and networks and the role of the family -of-origin influences as a primary force for communication on behavior of newly forming systems. Each family system develops its own communication meanings. There is not one right way to communicate within a family but may be indefinitly large change of family life and communication behavior. Study on functional family communication helps to gain a better understanding of dynamics of family communication and ability of a new insight into the family.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.365-372
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• 2017

Squat exercise is one of the important free weight exercises that can safely and effectively expect the athletic performance by establishing the rationale. Therefore, it is necessary to study the side effects caused by incorrect exercise, scientific countermeasures and to develop a exercise estimation model. It is effective and accurate to use a variety of assistive devices to calibrate athletic posture. The issues of the structural analysis for designing a foot plate for squat exercise is to model the behavior by the dynamic behavior. It should be consider that the center of gravity of each segmented body is different when the maximum load is applied. It is applied to complete system design through simulation method with kinematic dynamic, ground reaction force and load analysis for the free weight exercise equipment, VR device, and safety foot plate. In this paper, the authors propose the design method for the vertical load distribution applied in the design of the foot plate used for the squat exercise mechanism, and based on these results, design make the more safe and reliable free weight exercise equipment system.

• Journal of Environmental Science International
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• v.3 no.2
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• pp.111-128
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• 1994

The distributions of sea surface temperature across the Cheju Strait and the Korea Strait have been measured by using a thermometer installed on board No.1 Cheju, a ferry that operates regularly between Pusan and Seogwipo. The data from 14 October 1991 to 15 August 1992 were analyzed in this paper. A clear temperature front is wormed at the adjacent sea of Geomundo, and its position is not fixed and moves north and south. The slow northward movement of the front can easily be traced, but the southward movement from March to October is obscure. The temperature contrast in the Cheju Soait and the Korea Strait is very we in this period. Some periodical fluctuations with a period of several tens of days are observed in the region of the temperature front from November to February. This fluctuation seems to be caused by winter heat flux exchange and the strong southeastward wind force. The result shows that continous observation of the sea surface temperature distribution across the Cheju Strait and the Korea Strait yields a good method for monitoring the presence of Tsushima Warm Current and the fluctuations of South Korea Coastal Water. The formation and structure of shelf front in the Cheju Strait and the Korea Strait was analysed based on the detailed oceanographic data observed during the period of 1990-1992. The analysis shows that well-defined fronts were formed through yearly around the Chuja Island, particularly, in summer. In nature, its structure and formation position can be changed easily from year % year and by season. But, in region of the Korea Strait this front is relatively weak.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.47-56
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• 2010

The construction of new roads and the consistent extension of already-existing roads or the line-shape revision of those roads are increased with the governmental investment to SOC facilities currently. Accordingly, the road cut slopes are in the trend of rapidly increasing. As the road slope has increased, a lot of human and property damages has entailed consequently and in the local case, numerous studies have carried out aiming at minimizing this damages caused by the rockfall and landslide. In general, standard falling rock prevention facility has employed for most of the local road slope based on "Guide for Installation and Management of Road Safety Facilities" published by MLTM(the Ministry of Land, Transport, and Maritime Affairs) but profound doubt has raised as to whether this rockfall prevention facility would function properly enough to prevent rockfall efficiently without any damages in case of actual occurrence of rockfall. In addition, it is a reality that in most cases, such work is relied on overseas technology as a whole as the local technical level is low and in case of rockfall prevention net, it is judged that a study on rockfall prevention net that is able to endure more powerful rockfall energy is required as the problem including net bursting is taken place as a result of enough bearing force being failed to be demonstrated due to its partial weak point(not uniformly made). Under this background, in this study, three kinds of model depending on mesh size of expanded metal that is considered to have an adoptability as rockfall prevention net, as target are selected and characteristics depending on mesh size of expanded metal is intended to be researched through a pull-out test performance by using pull-out test equipment rockfall prevention net.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.2
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• pp.81-89
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• 2014

The present study aims to design an optimized hull shape of a floating pendulum-type wave energy converter(WEC). The purpose of these structure is to improve the performance and stability of the WEC by reducing its motion under operating and survival wave conditions. In this study, motion reduction structures, like restoring and dampling plates were installed on a floating pendulum WEC that has been the subject of previous studies. Restoring plates were installed to increase the restoring force and shift the natural period to a shorter period. Damping plates were installed to shift the natural period to a longer period by increasing the added mass. The effects of the structures were then analyzed under different incident wave conditions. The design parameters for the motion reduction structures were size, shape, and installed position. The wave-induced motion characteristics and performance of the floating pendulum WEC were also investigated numerically. Based on the simulation results, we are able to optimize the motion reduction structure of the WEC, thus improving its efficiency and durability.

• Journal of Biomedical Engineering Research
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• v.25 no.6
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• pp.519-523
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• 2004

This study investigates micro-structural and mechanical properties of trabecular bone in human femoral head with and without osteoporosis using Micro-CT and finite element-model. 15 cored trabecular bone specimens with 20min of diameter were obtained from femoral heads with osteoporosis (T-score > -2.5 ) resected for total hip arthroplasty, and 5 specimens were removed from femoral head of cadavers, which has no history of musculoskeletal diseases. A high-resolution micro-CT system was used to scan each specimen to obtain histomorphometry indices. Based on obtained micro-images(pixel size=21.31㎛), a FE-model was created to determine mechanical property indices. While non-osteoporosis group had increases trabecular thickness, bone volume, bone volume fraction, degree of anisotropy and trabecular number compared with those of non-osteoporotic group, the non-osteoporotic group showed decreases in trabecular separation and structure model index. Regarding the mechanical property indices, reaction force, apparent stress and young's modulus were 1ower in osteoporotic group than in non-osteoporotic group. Our data shows salient deteriorations in trabecular micro-structural and mechanical properties in human femoral head with osteoporosis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.936-944
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• 2019

Submarines, which have been called an invisible force, are strategic underwater weapon systems that perform missions such as anti-surface warfare, anti-submarine warfare, and high payoff target strikes with the advantage of underwater covertness. A submarine should be able to withstand the hydrostatic pressure of the deep sea. In this respect, the submarine pressure hull, as the main structural system to resist the external pressure corresponding to the submerged depth, should ensure the survivability from hazards and threats such as leakage, fires, shock, explosion, etc. To do this, the initial scantling of the submarine pressure hull must be calculated appropriately in the concept design phase. The shape of the aft transition ring varies according to its connection with the submarine aft end conical structure, pressure hull cylindrical part, and non-pressure hull of the submarine; the design of the aft transition ring should not only take into account stress flow and connectivity but also the cost increase due to the increased man-hours of its complex geometry. Therefore, trade-off studies based on the four different shapes of the aft transition ring are carried out considering both the review of the structural strength through nonlinear finite element analysis (FEA) and economic feasibility by reviewing the estimations of the manufacturing working days and material costs. Finally, the most rational structural aft transition ring shape for a submarine amongst four reviewed types was proposed.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.4
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• pp.526-552
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• 1994

The extent and direction of movement of removable partial dentures during function are influenced by the nature of the supporting structures and and the design of the prosthesis. Since forces are transmitted to the abutment teeth through occlusal rests, guide planes and direct retainers during functional movements, proper design based on the avaialble research data will maintain the health of abutment teeth and their supporting structures. The purpose of this in vitro study is evaluating stress distribution clinically around the abutment teeth prepared following 4-type clasping systems for unilateral free-end removable partial dentures. Three-Dimensional Photoelastic Stress Analysis method was used because it shows a visual display of stresses of the simulated abutment teeth and residual ridges and reveals stress concentration that can be read at any given points in terms of direction and magnitude. For this study, the author fabricated 4 mandibular photoelastic epoxy models missing left 1st and End molar. Epoxy models were duplicated and 4 unilateral removable partial dentures were construe- ted in accordance with 4-type direct retainers. Unilateral free-end removable partial dentures were positioned on their own models. 6kg force was loaded on the every removable partial dentures of the epoxy model on the central fossa of mandibular left 1st molar vertically by the loading device. After the stress was frozen in a stress freezing furnace, 6 specimens of 6-mm thickness were made from every epoxy model and examined with the circular polariscope. The results were as follows : 1. Generally I-bar clasp revealed the most favorable stress distribution around the abutment teeth. 2. At the end portion of the free-end ridge, Back action clasp showed the highest stress concentration at the bucco-lingual and top portions of the residual alveolar ridge. 3. At the distal area of the abutment teeth, Akers clasp and Roach clasp showed higher stress concentration bucco-lingually and apically than the others. 4. To the abutment tooth, I-bar clasp showed the least stress distribution bucco-lingually but the others showed irregular stress distribution. 5. At the mesial area of the abutment teeth, the order of effective stress distribution was I-bar clasp, Back-action clasp, Akers clasp and Roach clasp. There was big difference of stress distribution between them. 6. At the right 2nd premolar and 1st molar, the stress concentration of Akers clasp was a little high but that of I-bar clasp was low.