• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.11
• /
• pp.2636-2656
• /
• 2013

To improve the cooperative efficiency of node cooperation and multiple access performance for multihop wireless networks, a priority-differentiated cooperative medium access control protocol with contention resolution (CRP-CMAC) is proposed. In the protocol, the helper selection process is divided into the priority differentiation phase and the contention resolution phase for the helpers with the same priority. A higher priority helper can choose an earlier minislot in the priority differentiation phase to send a busy tone. As a result, the protocol promptly selects all the highest priority helpers. The contention resolution phase of the same priority helpers consists of k round contention resolution procedures. The helpers that had sent the first busy tone and are now sending the longest busy tone can continue to the next round, and then the other helpers that sense the busy tone withdraw from the contention. Therefore, it can select the unique best helper from the highest priority helpers with high probability. A packet piggyback mechanism is also adopted to make the high data rate helper with packet to send transmit its data packets to its recipient without reservation. It can significantly decrease the reservation overhead and effectively improve the cooperation efficiency and channel utilization. Simulation results show that the maximum throughput of CRP-CMAC is 74%, 36.1% and 15% higher than those of the 802.11 DCF, CoopMACA and 2rcMAC protocols in a wireless local area network (WLAN) environment, and 82.6%, 37.6% and 46.3% higher in an ad hoc network environment, respectively.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.21 no.1
• /
• pp.59-67
• /
• 2018

Purpose: to compare cut off points corrected for age and gender (COOP) with fixed cut off points (FCOP) for fasting plasma insulin and Homeostatic model assessment-insulin resistance (HOMA-IR) for the diagnosis of IR in obese children and adolescents and their correlation with dyslipidemia. Methods: A multicenter, cross-sectional study including 383 subjects aged 7 to 18 years, evaluating fasting blood glucose, plasma insulin, and lipid profile. Subjects with high insulin levels and/or HOMA-IR were considered as having IR, based on two defining criteria: FCOP or CCOP. The frequency of metabolic abnormalities, the presence of IR, and the presence of dyslipidemia in relation to FCOP or CCOP were analyzed using Fisher and Mann-Whitney exact tests. Results: Using HOMA-IR, IR was diagnosed in 155 (40.5%) and 215 (56.1%) patients and, using fasting insulin, 150 (39.2%) and 221 (57.7%), respectively applying FCOP and CCOP. The use of CCOP resulted in lower insulin and HOMA-IR values than FCOP. Dyslipidemia was not related to FCOP or CCOP. Blood glucose remained within normal limits in all patients with IR. There was no difference in the frequency of IR identified by plasma insulin or HOMA-IR, both for FCOP and CCOP. Conclusion: The CCOP of plasma insulin or of HOMA-IR detected more cases of IR as compared to the FCOP, but were not associated with the frequency of dyslipidemia. As blood glucose has almost no fluctuation in this age group, even in the presence of IR, fasting plasma insulin detected the same cases of IR that would be detected by HOMA-IR.

• Korean Journal of Poultry Science
• /
• v.11 no.1
• /
• pp.33-39
• /
• 1984

The pattern of economic integration in the broiler industry can be grouped into three categories; 1) non-integration, 2) quasi-integration and 3) complete-integration. It is general to see that the non-integration is quite common under the market conditions of perfect competition, whereas the complete integration is more preferable in the imperfect competition. The quasi-integration, however, exists at all phases where the complete integration is not fully formed and implemented, but the non-integration has begun to alter its nature into integrated structure. The broiler industry in Korea has been characterized with the typically non-integrated independent operation, resulting in considerable price fluctuation and unstable industry as a whole. As a means of solving out the problem stemed from the non-integrated, growers and agribusinessmen involved in broiler industry have tended to develope the regular customer relationship prevailed between two parties. In fact, it has been practiced for years that most growers have been dealt with factor suppliers or processors on a regular basis for advantages of better price and quality, useful information, management help and so forth. Under the customary transaction, no formal contract has been made due to simple buyers and sellers relations, not like the one used to be performed in the form of contractual agreement. The broiler industry realizes the direction to go ahead toward the formal arrangement of integrated system from current regular transactions. As more Vowers, suppliers and processors recognize the necessity of it, the non-integrated industry appears to become the partially integrated by developing the existing customer relationship in such a way that functions of integrators are. further expanded and better organized. As a result, a type of quasi-integration started to show up by an integrator dominated in the field of hatching, feedmilling, dressing and by a grower's coop, It is concluded, therefore, that the evolution of quasi-integration in Korea's broiler industry is continuously taking place, implying the close approach to the completely integrated broiler production and marketing system.

• The Korean Journal of Food And Nutrition
• /
• v.32 no.6
• /
• pp.643-650
• /
• 2019

The purpose of this study was to investigate the quality of dehulled soybean (DHSB), and the rapid preparation possibility of soybean milk with DHSB (SM-DHSB), and then the quality of SM-DHSB. In DHSB, the moisture content decreased, the crude protein, crude fat, minerals, and carbohydrate contents increased, and the isoflavone (daidzein, genistein and glycitein) content was similar to that of soybean (SB). The water absorption rate of DHSB for soybean milk preparation was higher than that of SB. In the results of SM-DHSB and soybean milk (SM) qualities, the crude protein content, total solid content, and the viscosity of SM-DHSB were higher, the yield and the proximate composition (except crude protein) were similar, and the Biji production rate, and total dietary fiber content of SM-DHSB were lower compared to the SM. In terms of the isoflavone contents of SM-DHSB, daidzein and genistein content were similar, and glycitein content was lower compared with the SM. Consequently, these results suggest the possible use of DHSB for rapid SM-DHSB preparation, because the soaking time was decreased by the high water absorption rate of DHSB in the SM preparation, and the quality of SM-DHSB improved compared to those of the SM.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.718-725
• /
• 2016

In this study, the plastic flow curve of commercially pure titanium sheet (CP Ti) actively used in the plate heat exchanger etc., was evaluated. The plastic flow curve known as hardening curve is a key factor needed in conducting finite element analyses (FEA) for the forming process of a sheet material. A hydraulic bulge test was performed on the CP Ti sheet and the strain in this test was measured using the DIC method and ARAMIS system. The measured true stress-true strain curve from the hydraulic bulge test (HBT) was compared with that from the tensile test. The measured true stress-true strain curve from the hydraulic bulge test showed stable plastic flow curve over the strain range of 0.7 which cannot be obtained in the case of the uniaxial tensile test. The measured true stress-true strain curve from the hydraulic bulge test can be fitted well by the hardening equation known as the Kim-Tuan model.

• Journal of Families and Better Life
• /
• v.32 no.5
• /
• pp.163-178
• /
• 2014

The purpose of this study is to validate the mediating effects of anger expression types for anxiety on the violent behaviors of adolescent school violence offenders. For the purpose of this study, 114 adolescent school violence offenders and 178 general youths were selected. Through the structural equation model, the mediating effects of anger expression types that are manifested in the path of violent acts of adolescent school violence offenders and general youths are verified. The major findings of this study are as follows. First, for both groups, the same path of violent behavior through anger-in and anger-out was followed: youths repress anger when they have higher anxiety, and when too much anger is repressed, anger-out increases, which results in more violent behaviors. Second, the level of anxiety of adolescent school violence offenders has direct effect on the responsive violent behaviors while the level of anxiety of general youths does not have direct effect on violent behaviors. Third, although the anxiety of adolescent school violence offenders may increase violent behaviors through the paths of acting-in and acting-out, violent behaviors can be reduced by reducing anger-out. Therefore, to reduce the violent behaviors of adolescent school violence offenders, intervention is needed for those who repress their anger due to anxiety; professional education is also required for adolescent school violence offenders to help them control their anger.

• Journal of Communications and Networks
• /
• v.14 no.6
• /
• pp.640-652
• /
• 2012

Many studies have investigated the smart grid architecture and communication models in the past few years. However, the communication model and architecture for a smart grid still remain unclear. Today's electric power distribution is very complex and maladapted because of the lack of efficient and cost-effective energy generation, distribution, and consumption management systems. A wireless smart grid communication system can play an important role in achieving these goals. In this paper, we describe a smart grid communication architecture in which we merge customers and distributors into a single domain. In the proposed architecture, all the home area networks, neighborhood area networks, and local electrical equipment form a local wireless mesh network (LWMN). Each device or meter can act as a source, router, or relay. The data generated in any node (device/meter) reaches the data collector via other nodes. The data collector transmits this data via the access point of a wide area network (WAN). Finally, data is transferred to the service provider or to the control center of the smart grid. We propose a wireless cooperative communication model for the LWMN.We deploy a limited number of smart relays to improve the performance of the network. A novel relay selection mechanism is also proposed to reduce the relay selection overhead. Simulation results show that our cooperative smart grid (coopSG) communication model improves the end-to-end packet delivery latency, throughput, and energy efficiency over both the Wang et al. and Niyato et al. models.

• Journal of the Economic Geographical Society of Korea
• /
• v.21 no.3
• /
• pp.254-269
• /
• 2018

The aim of this paper is to identify the components of the sustainable regional ecosystem of social economy enterprises (hereafter 'regional ecosystem'), and to explore the principles of reciprocity, regard and public policy, which have a fundamental impact on the development of such regional ecosystem. The regional ecosystem is an interactive system of the stakeholders who are related to the process of planning, producing, distributing and selling goods and services, and the agents who maintain and spread their social value orientation. This system operates through the interaction of 'local network (business relations and social relations)', 'intermediary organization' and 'public role.' On the basis of the conceptual framework on the regional ecosystem, the result of the in-depth analysis on the case of Gorang-erang Coop shows the interaction of reciprocity and public policy with respect to regard within the context of a characteristic of the regional ecosystem.

• Journal of the Korean Chemical Society
• /
• v.53 no.3
• /
• pp.266-271
• /
• 2009

In the recently synthesized rare earth transition metal carbide $La_7O_{s4}C_9$ one finds one-dimensional organometallic $[O_{s4}C_9]^{21-}$ polymers embedded in a $La^{3+}$ ionic matrix. The electronic structure of the polymeric $[O_{s4}C_9]^{21-}$ chain was investigated by density of states (DOS) and crystal orbital overlap population (COOP), using the extended Huckel algorithm. A fragment molecular orbital analysis is used to study the bonding characteristics of the $C_2$ units in $La_7O_{s4}C_9$ containing $C_2$ units and single C atoms as well. The title compound contains partially filled Os and carbon bands leading to metallic conductivity. As the observed distances already indicated, the calculations show extensive Os-C interactions. The C-C bond distance in the diatomic $C_2$ units ($d_{C-C}$=131 pm) in the solid is significantly increased relative to $${C_2}^{2-}$$ or acetylene, because antibonding $1{\pi}_g$ orbitals are partially filled by the Os-$C_2(1\;{\pi}_g)$ bonding contribution found at and below the Fermi level.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.3
• /
• pp.266-273
• /
• 2021

Objective: The objective of this study was to suggest improvement methods for investigations and systems through a review of musculoskeletal risk factor investigation reports conducted in the workplace. Methods: A total of 34 reports on musculoskeletal risk factor investigations were reviewed. To confirm the appropriateness of the evaluation, reevaluation was conducted through a field investigation using other evaluation tools. In order to understand the effectiveness of the improvement plan, a survey was conducted with those in charge of tasks with ergonomic burdens. Results: As a result of performing a field survey using the work sampling method recommended by the KOSHA (Korea Occupational Safety and Health Agency) for ten tasks, eight tasks were determined to pose an ergonomic burden. When 30 tasks were evaluated with RULA (rapid entire body assessment), 90% of them were evaluated at a higher level than the results of the workplace survey. Among the improvement measures, only 36% of the field workers affirmed them, and in only 19% of the workplaces were actual improvements made. Conclusions: In order to improve the ergonomic investigation system for risk factors in the ergonomic burden task, it is necessary to secure the objectivity of the evaluation performed by the institution and enable the active participation of workers in improvement activities.