• Journal of Periodontal and Implant Science
• /
• v.46 no.3
• /
• pp.152-165
• /
• 2016

Purpose: This study investigated the effects of bone density and crestal cortical bone thickness at the implant-placement site on micromotion (relative displacement between the implant and bone) and the peri-implant bone strain distribution under immediate-loading conditions. Methods: A three-dimensional finite element model of the posterior mandible with an implant was constructed. Various bone parameters were simulated, including low or high cancellous bone density, low or high crestal cortical bone density, and crestal cortical bone thicknesses ranging from 0.5 to 2.5 mm. Delayed- and immediate-loading conditions were simulated. A buccolingual oblique load of 200 N was applied to the top of the abutment. Results: The maximum extent of micromotion was approximately $100{\mu}m$ in the low-density cancellous bone models, whereas it was under $30{\mu}m$ in the high-density cancellous bone models. Crestal cortical bone thickness significantly affected the maximum micromotion in the low-density cancellous bone models. The minimum principal strain in the peri-implant cortical bone was affected by the density of the crestal cortical bone and cancellous bone to the same degree for both delayed and immediate loading. In the low-density cancellous bone models under immediate loading, the minimum principal strain in the peri-implant cortical bone decreased with an increase in crestal cortical bone thickness. Conclusions: Cancellous bone density may be a critical factor for avoiding excessive micromotion in immediately loaded implants. Crestal cortical bone thickness significantly affected the maximum extent of micromotion and peri-implant bone strain in simulations of low-density cancellous bone under immediate loading.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.7
• /
• pp.25-35
• /
• 2008

In domestic cases, the standard support pattern of 2-lanes road tunnels is presented because construction experience and high degree various data was abundant. But, it is not desirable to apply standard for 2-Arch tunnels that the precedent and measuring data is insufficient existing support pattern blasting plan and interpretation of separate way concerning specific terrain and rock quality. In this study, behavior according to load distribution ratio and Unsymmetrical Pressure about standard support pattern which is applied in design and construction of 2-arch tunnels was analysed and the examination of blasting vibration has influence on the center wall is conducted as a consequence reasonableness of support whether or not with presumed support pressure and ground reaction curve method. In result appropriateness of standard support pattern, support quantity is proper but considers specific terrain and rock quality condition when design and construction of further step 2-arch tunnel standard support pattern must be decided by considering terrains, soil properties and construction condition of the objective tunnel.

• Journal of the Korean Ceramic Society
• /
• v.41 no.4
• /
• pp.302-312
• /
• 2004

This paper presents the experimental results on the properties of the cement mortar with polycarboxylate-type superplasticizers PCA) which were synthesized by different mole ratio of methoxypoly(ethyleneglycol)monomethacrylate (MPEGMAA) and methacrylic acid (MAA) and by different length of polyethyleneoxide (PEO). As the PEO chain was longer and mole ratio of [MPEGMAA]/[MAA] was lower, the fluidity of cement mortar was better. The setting time of mortar with PCA was retarded, and as PEO chain was shorter and [MPEGMAA]/[MAA] was lower, it was more retared. Espeacially, when the molecular weight of MPEGMAA was 475(repeat unit of ethylene oxide=l0), the degree of retardation was the highest of them. The surface tensions of PCA solutions were lower than that of water due to the effect of PEO chain, and also the pore size distribution of cement mortar was influenced by it. The pores in cement mortar with PCA at 28 days were macropores in the range of 7 to 370$\mu\textrm{m}$, and accordingly, the densities and compressive strengths of mortar were lower than those of OPC mortar.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.5
• /
• pp.465-470
• /
• 2012

This paper proposes a distributed autonomous control method of swarm robot behavior strategy based on artificial immune system and an optimization strategy for artificial immune system. The behavior strategies of swarm robot in the system are depend on the task distribution in environment and we have to consider the dynamics of the system environment. In this paper, the behavior strategies divided into dispersion and aggregation. For applying to artificial immune system, an individual of swarm is regarded as a B-cell, each task distribution in environment as an antigen, a behavior strategy as an antibody and control parameter as a T-cell respectively. The executing process of proposed method is as follows: When the environmental condition changes, the agent selects an appropriate behavior strategy. And its behavior strategy is stimulated and suppressed by other agent using communication. Finally much stimulated strategy is adopted as a swarm behavior strategy. In order to decide more accurately select the behavior strategy, the optimized parameter learning procedure that is represented by stimulus function of antigen to antibody in artificial immune system is required. In this paper, particle swarm optimization algorithm is applied to this learning procedure. The proposed method shows more adaptive and robustness results than the existing system at the viewpoint that the swarm robots learning and adaptation degree associated with the changing of tasks.

• Journal of the Korean Home Economics Association
• /
• v.44 no.10
• /
• pp.67-77
• /
• 2006

This study was performed investigate eating behaviors and their association with obesity in Korean elderly people. A total of 9,408 (male 4,487, female 4,921) Korean adults aged 40 to 69 years were interviewed and examined from May 2001 to Feb 2002. The subjects were classified into 4 weight status groups based on body mass index (BMI, $kg/m^2$): under weight, BMI<18.5; normal, $18.5{\leq}BMI\leq24.9$; overweight, $25.0{\leq}BMI\leq29.9$; obesity, $BMI\geq30.0$. Anthropocentric parameters, eating behavior, and preference of cooking method and taste were examined. In male, distribution of weight status by BMI was under weight 2.4%, normal 58.1%, over weight 36.7%, obesity 2.8%. As the BMI increased, the rate of skipping meal, snacks, and eating out were increased and the rate of eat alone was decreased. When compared according to the weight status by BMI, the frequency of the steamed, roasted, fried, seasoned, and soup intake rates were increases in the cooking methods and preference of greasy taste was increased by degree of obesity. In female, distribution of weight status by BMI was under weight 1.4%, normal 52.8%, over weight 38.6%, obesity 7.2%. There were differences in the rate of eating out, snacks, the frequency of fried food intake rates, and preferences of salty, hot, greasy taste according to the weight groups by BMI. In this results, we suggests that keep regular meal and keep away from the high-fat, salty, stimulative foods for prevent and administer the obesity in Korean adults meal and female.

• Clean Technology
• /
• v.12 no.3
• /
• pp.157-164
• /
• 2006

In order to purify 2-methylnaphthalene as main impurity included in naphthalene, SLE (solid-liquid equilibria) on two components system including naphthalene and 2-methylnaphthalene were measured and a layered melt crystallization has been studied. SLE in the present system is shown a simple eutectic mixture and the experimental results using DSC method is similar to the static method. Purity and yield of naphthalene in crystal depended mainly on the cooling rate: Increasing cooling rate, the purity of naphthalene in crystal increase, whereas the yield of that decrease. The effective distribution coefficient (Keff) as the degree of impurity removal was observed to decrease with decreasing of cooling rate. Therefore, the purity of naphthalene by melt crystallization can be enhanced to 5~7 %.

• Solar Energy
• /
• v.18 no.1
• /
• pp.57-67
• /
• 1998

A study on a buoyancy effect by the temperature difference between a inner room air and a inflowing cool air and also by Inlet velocity can contribute greatly to enhance performance of air conditioning system, so the study on the distribution characteristics of inflowed cool air is important to analyze the cool air storage in a room. For this study, in the real-sized model room, the temperature differences between inflowing cool air and inner room air are 10, 20, $30^{\circ}C$, and the inlet velocities of inflowing cool air are 1, 2, 3m/s respectively as dynamic parameters. Also, a anemos and a vane type diffuser are used as inlet geometric conditions. Following conclusions have been obtained through this study. 1) In case of the anemos type diffuser, it is found that a dimensionless temperature profile is low and the distribution of the inflowed cool air is uniform. and also, all diffuusers have a low temperature of the inner room as increasing the inlet velocity. 2) A mixing takes place rapidly in case of the anemos type diffuser when the temperature difference is low ${\Delta}T=10^{\circ}C$ and the inletvelocity is high V=3m/s. and the mixing degree is higher with the anemos type diffuser than the vane.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2002.11a
• /
• pp.280-287
• /
• 2002

Most Technological laws of Korea are almost identical to those of Japan. Electricity was not introduced to Korea until lighting ceremony in Kyong-Bok palace observed in 1887. Since Korea was annexed to Japan in 1910, Korea have applied Japanese law and regulations made by Chosun government-general. And public works were under Japan control. Korea accepted adopted the power plants of America, codes of NESC, ASME / ANSI, MEMA while Japan accepted or adopted only IEC. Our generation distribution system takes American style while our consumer side takes Japanese style. As global trade system was transferred GATT into WTO, the technological standards, certification, construction and testing are in harmony internationally. The WTO / TBT agreement came in effect after 12th, April, 1979. The sections in the agreement require the members to exchange their own standards and codes for the harmonized ones by degree. The Korean distribution system has a strong resemblance to American system so that the internal engineers are confused in application of the relevant standards. IEC60364 and NEC are technologically similar but practically unconvertible because both have their different originality, that is to say Europe and USA. This paper deals with the fundamental elements of electrical safety system on review of IEC 60364 and NEC. This paper considers how engineers should apply IEC60364 and NFPA 70(NEC) based on all-the-way review of them.

• Journal of Environmental Science International
• /
• v.12 no.2
• /
• pp.111-117
• /
• 2003

This paper investigates preliminarily spatial distribution soil organic matter (SOM), nitrogen (N) and phosphorus (P) and its environmental influence in wetland soil of different vegetation landscape in the Yellow River Mouth. The result shows the SOM and total nitrogen (TN), efficient N, efficient P in top layer soils of different vegetation district have significantly different content, The SOM is shown as Calamagrostis epigeios wetlands > Phragmites cmmunis wetlands > Tamarix chinensi wetlands above tidal > Suaeda salsa wetlands in high tidal > Tamarix chinensi wetlands in high tidal > tidal flats, the arrange of the TN and efficient N content is the same except that the content in Suaeda salsa wetlands in high tidal is heavier than Tamarix chinensi wetlands in high tidal. In different vegetation landscape wetland types the vertical change of soil nutrients are obvious except for p, gradually decrease from the upper to the lower. This case reflects the function of the vegetation on the wetland development of soil and proves the wetland soil has the characteristic of new born and bad degree of development. SOM, TN, efficient N and efficient P content in wetland soils have significantly positive correlation, but TP have no correlation with them but efficient p. The contents of TN in wetland soils range from 58~1480 mg/kg, total average content 408 mg/kg, average content of above 30 cm is 625 mg/kg. The range of TP content in the soil is 372~1042 mg/kg, total average is 569 mg/kg, average content of above 20 cm is 611 mg/kg. According the P it occurs mainly as calcium phosphates, and the validity is lower, therefore, N and P in the new born wetlands cannot produce serious impact on the environments at present.

• Journal of Distribution Science
• /
• v.16 no.7
• /
• pp.57-65
• /
• 2018

Purpose - Recently, internet access and social network utilization using smart phone are increasing. In such a smart environment, interactive activities such as information generation, information searching and information sending are increasing rapidly on-line environment. Therefore, consumers tend to purchase something according to eWOM and also meet the social consensus online environment. In connectivity society, consumers became accessible and engaged in the opinions of others easily. Many decisions that seem like personal decisions are actually social decisions on online connectivity. This paper seeks to explore factors that can help generate a social decision on purchasing of new products in an online environment. Research design, data, and methodology - The process of collecting a lot of wisdom and making an agreement online is called social decision. The purpose of this paper is to examine empirically the influence of factors such as online ties, online eWOM expectancy and online information behavior on online social decision. In addition, We studied online social decision by analyzing the moderating effect of new product innovation. To understand this structural relationship, research hypotheses and research models were set up and empirical analysis was conducted. In order to verify the hypothesis, 208 questionnaires were collected from the residents of Seoul city/Gyeonggi province. The answered questionnaire verifies reliability and validity using SPSS/AMOS and test hypotheses through path analysis and multiple regression analysis. Results - According to the research results, First, online ties don't have a positive impact on online social decision, Second, online eWOM expectancy have a positive impact on online social decision. Third, online information behaviors have a positive impact on online social decision. The degree of innovation of new products have a moderating effect between Independent variables of three factors and dependent variable of social decision. Conclusions - Social decisions have a positive impact on purchasing decisions about new product. There is a great significance in the fact that the online social influence and online social decision have been studied academically. It is meaningful that we have studied in depth the changing phenomenon of consumer purchase decision process in smart environment. The results of these studies provide academic and practical implications.