• Journal of Korean Society of Forest Science
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• v.104 no.2
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• pp.267-276
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• 2015

This study suggests a macroscopic method of evaluating forest recreation function based on physical characteristics of forests. The method was verified by a correlation between forest recreation function in popular top 45 mountains and popularity among them, with using data-mountain area, height, distance between mountain and cities, population around mountain, and size of public service. According to analysis of the forest recreation function, it is shown that top 8 mountains, including Jirisan and Seoraksan, provide over 64% of total recreation function, while they serve the function relatively lower than mountains near mega cities-Bukhansan in Seoul-do, in terms of the function per unit area ($km^2$). It is because, in a case of national and provincial mountains, the size of mountain is likely a critical factor for determining recreation function and the distance influences on it relatively lower. These findings implicate that a large size of forests bring the recreation function to visitors on nationwide level, whileas forests in suburban provide intensively it to near population to near population.

• Journal of the Ergonomics Society of Korea
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• v.35 no.6
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• pp.595-609
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• 2016

Objective: The purpose of this study was to develop and validate the guidelines for Medic Work Table (MWT) based on the anthropometric data of medical technologists. Background: Users' anthropometric data such as sitting height, sitting elbow height, knee height, and so on are significant factors for designing comfortable and useful furniture. Thus, many guidelines for different types of desks and chairs based on the users' anthropometric data have been suggested to many researchers. However, few researches have been conducted to provide design guidelines for MWT for blood collecting task. Medical technologists often use their upper extremities to perform blood collecting task with high repetitions. These repeated motions could be a critical factor in the prevalence rate of Work-related Musculoskeletal Disorders (WMSDs). Therefore, a study on ergonomic design of MWT would be essential in preventing the WMSDs and improving the quality of the working environment of medical technologists. Method: This study suggested design guidelines for ergonomic MWT by focusing on the heights of the upper side and underside, depths of the inside and outside, and width of MWT through anthropometric studies and literature reviews. Afterwards, a new MWT was made using the suggested design guidelines for this study. Five healthy medical technologists participated to evaluate the original MWT and new MWT. All participants took part in the range of motion (ROM) test, electromyography (EMG) muscle activity test, and usability test to validate the suggested guidelines in this study. EMG signals of related muscles (Flexor Carpi Ulnaris, Extensor Carpi Ulnaris, Deltoid Anterior, and Biceps Branchii) were recorded through the surface electromyography system from both the original MWT and the new MWT. The ROM test of the shoulder and elbow flexion was also assessed using motion sensors. Results: The newly designed MWT showed decreased ROMs of the shoulder and elbow up to 22% and 18% compared to the original MWT. The muscle activities in the new MWT also showed a decrease of 13% in Anterior Deltoid, 6% in Biceps Brachii, 5% in Flexor Carpi Ulnaris, and 8% in Extensor Carpi Ulnaris muscle groups, compared to the original MWT. In the usability test, the satisfaction score of the new MWT was also 56.1% higher than that of the original MWT. Conclusion: This study suggested guidelines for designing MWT and validating the guidelines through qualitative and quantitative analyses. The results of motion analysis, muscle activity, and usability tests demonstrated that the newly designed MWT may lead to less physical stress, less awkward posture, and better physical user interface. Application: The recommended guidelines of the MWT would be helpful information for designing an ergonomic MWT that reduces physical loads and improves the performance of many medical technologists.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.53-59
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• 2002

Background: Clinical observations and laboratory studies have supported an immune basis for most acquired aplastic anemias, with the majority of patients responding to immunosuppressive therapy. Fas, a member of the tumor necrosis factor (TNF) receptor superfamily is a critical downregulator of cellular immune responses. Proinflammatory cytokines like interferon gamma (IFN-${\gamma}$) and TNF-${\alpha}$ can induce Fas expression and render hematopoietic progenitor cells susceptible to Fas-induced growth suppression and apoptosis. Methods: In order to investigate the involvement of apoptosis in the pathogenesis of aplastic anemia (AA), we measured the expression of Fas antigen and caspase-3 on bone marrow (BM) mononuclear cells (MNCs) of AA in the presence or absence of IFN-${\gamma}$, TNF-${\alpha}$, or macrophage inflammatory protein 1-${\alpha}$ (MIP-$1{\alpha}$). Results: We confirmed that AA BM MNCs were more apoptotic and highly expressed Fas antigen than normal donors. Stimulation by IFN-${\gamma}$, TNF-${\alpha}$, or MIP-$1{\alpha}$ increased Fas antigen and caspase-3 expression in AA BM MNCs than BM MNCs of normal donors. Anti-Fas monoclonal antibody enhanced IFN-${\gamma}$, TNF-${\alpha}$, or MIP$1{\alpha}$ mediated caspase-3 expression in BM MNCs of normal donors. Among these three cytokines, IFN-${\gamma}$ enhanced apoptosis most strongly via Fas-caspase-3 pathway. Conclusion: These results suggest that Fas signal pathway may play a role in the pathophysiology of aplastic anemia and negative hematopoietic regulators like IFN-${\gamma}$ can induce apoptosis of bone marrow progenitors in part by Fas induction.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.1
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• pp.20-33
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• 2002

Usage of ATM AAL2 packets becomes dominant to increase transmission efficiency of voice traffic in the backbone network. In case of voice service that uses AAL2 mechanism, if resources of network are enough, connection of new call is accepted. However, due to packets generated by the new call, transmission delay of packets from old calls can increase sharply. To control this behavior, in this paper we present an AAL2 buffer management scheme that allocates a virtual buffer to each call and after calculating its propagation delay variation(PDV), decides to drop packets coming from each call according to the PDV value. We show that this packet dropping algorithm can effectively prevent abrupt QoS degradation of old calls. To do this, we analyze AAL2 packet composition process to find a critical factor in the process that influences the end-to-end delay behavior and model the process by K-policy M/D/1 queueing system and MIN(K, Tc)-policy M/D/1 queueing system. From the mathematical model, we derive the probability generating function of AAL2 packets in the buffer and mean waiting time of packets in the AAL2 buffer. Analytical results show that the AAL2 packet dropping algorithm can provide stable AAL2 packetization delay and ATM cell generation time even if the number of voice sources increases dramatically. Finally we compare the analytical result to simulation data obtained by using the COMNET Ⅲ package.

• Journal of Adhesion and Interface
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• v.4 no.3
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• pp.33-40
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• 2003

In this work, diglycidyl ether of bisphenol A (DGEBA)/polyetherimide (PEI) blends were cured using 4,4-diaminodiphenyl methane (DDM). And the effects of addition of different PEI contents to neat DGEBA were investigated in the thermal properties and fracture toughness of the blends. The contents of contents of containing PEI were varied in 0, 2.5, 5, 7.5, and 10 phr. The cure activation energies ($E_a$) of the cured specimens were determined by Kissinger equation and the mechanical interfacial properties of the specimens were performed by critical stress intensity factor ($K_{IC}$). Also their surfaces were examined by using a scanning electron microscope (SEM) and the surface energetics of blends was determined by contact angles. As a result, $E_a$ and $K_{IC}$ showed maximum values in the 7.5 phr PEI. This result was interpreted in the increment of the network structure of DGEBA/PEI blends. Also, the surface energetics of the DGEBA/PEI blends showed a similar behavior with the results of $K_{IC}$. This was probably due to the improving of specific or polor component of the surface free energy of DGEBA/PEI blends, resulting in increasing the hydrogen bonding of the hydroxyl and imide groups of the blends.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.767-776
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• 2014

Changes in climate have largely increased concentrated heavy rainfall, which in turn is causing enormous damages to humans and properties. Floods are one of the most deadly and damaging natural disasters known to mankind. The flood forecasting and warning system concentrates on reducing injuries, deaths, and property damage caused by floods. Therefore, the exact relationship and the spatial variability analysis of hydrometeorological elements and characteristic factors is critical elements to reduce the uncertainty in rainfall-runoff model. In this study, grid resolution depending on the topographic factor in rainfall-runoff models presents how to respond. semi-distribution of rainfall-runoff model using the model GRM simulated and calibrated rainfall-runoff in the Gamcheon and Naeseongcheon watershed. To run the GRM model, input grid data used rainfall (two event), DEM, landuse and soil. This study selected cell size of 500 m(basic), 1 km, 2 km, 5 km, 10 km and 12 km. According to the resolution of each grid, in order to compare simulation results, the runoff hydrograph has been made and the runoff has also been simulated. As a result, runoff volume and peak discharge which simulated cell size of DEM 500 m~12 km were continuously reduced. that results showed decrease tendency. However, input grid data except for DEM have not contributed increase or decrease runoff tendency. These results showed that the more increased cell size of DEM make the more decreased slope value because of the increased horizontal distance.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.400-408
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• 2003

Chloride ion inside concrete destroys the so-called passive film surrounding reinforcing bars inside concrete so that the so-called salt attack accelerates corrosion which is the most critical factor for durability as well as structural safety of reinforced concrete structures. Recently, as a solution of the salt attack, the ground granulated blast-furnace slag(GGBFS) have been used as binder or blended cement more extensively. In this paper, characteristics of chloride ion diffusion for the GGBFS concrete, which is known to possess better resistance to damage due to the chloride ion penetration than ordinary portland cement(OPC) concrete possesses, are analyzed and a chloride ion diffusion model for the GGBFS concrete is proposed by modifying an existing diffusion model for the OPC concrete. The proposed model is verified by comparing diffusion analysis results using the model accelerated chloride penetration test results for concrete specimens as well as field test results for an RC bridge pier. Then, an optimal resistance condition to chloride penetration for the GGBFS concrete is obtained according to degrees of fineness and replacement ratios of the GGBFS concrete. The result shows that the GGBFS concrete has better resistance to chloride ion penetration than OPC concrete has and the resistance is more affected by the replacement ratio than the degree of fineness of the GGBFS.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.469-475
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• 2008

It is obvious that chloride penetration through cracks can threaten the durability of concrete substantially, according to the previous studies of author. It was proposed that crack depth corrseponded with critical crack width from the surface is a crucial factor in view of durability design of concrete structures. It is now necessary to deal with chloride penetration through microcracks characterized with the mixing features of concrete. The purpose of this study is examining the effect of mix proportional features of concrete such as coarse aggregate, high strengtherize of concrete and reinforcement of steel fiber on chloride penetration through cracks. Although small size of coarse aggregate can lead to many microcracks in concrete, the cracks should not impact on chloride penetration directly. On the contrary, chloride should penetrate through cracks easily in concrete with a large size of coarse aggregate because mixrocracks are connected to each other. Second, high strength concrete has an excellent performance to resist with chloride penetration. However, for cracked high strength concrete, its performance is reduced upto the level of ordinary concrete. Finally, steel fiber reinforcement is effective to reduce chloride penetration through cracks because steel fiber reinforcement can lead to reduce crack depth significantly.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.2
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• pp.86-98
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• 1996

This study is intended to revaluate old tree, five of the shot of the Natural Monument and 66 shot trees under protection in the city at present. The study covers distribution, management of usage, investigation and research into various matters relating to the situation of old trees in Pusan. Because 60% of the old trees selected for protection is on private land, citizens have difficulty gaining access to them. Also space for growth is impinged on by various urban facilities. Some trees have problems of growth because the land is covered with cement and asphalt. As regards space for old trees, many places have been destroyed due to the lack of protection fences and the failure to establish a guidance board. Only 40% of the space has been set aside for rest. In these places the establishment of rest areas, benches and handy chairs is needed. And there are 20 holy places where people observe religious ceremonies. As for space security necessary for old trees according to trunk width, the minimum trunk width and availale area needed are more than 1:1.5, but less than 30% have the necessary space. The growth of many old trees is threatended because of the small apace for growth. The prescription of the boundary space is divided between inside and outside. This indicates the domain nature and space rank of the old tree. It can be classified into five forms for research purposes. The elements for prescription of critical space outside are connected with the security of space, and the elements relating to inside space portray the conditions for sensitive growth according to the institution and the ground conditions. The open and closed nature of old tree space has some connection with the relationship between usage and the intimacy of the user. Most of the spaces for old trees can't be used or are difficult to gain access to, so it is necessary to secure enough space for them. The 18 places, despite having easy access, are near farmland, hills or forest. So the intimacy factor is low, and the security of space of the old trees is not generally sufficient. Henceforth, it will be necessary to have security of area for old trees as well as maintenance control to protect them. Also the space should be used as a communal and recreation are in the city. It is the time to construct a landscaped area which people can easily approach, a place with a secure entrance where they can play, rest and converse.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.2
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• pp.18-28
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• 2011

This study is aimed at the improvement of administrative operations of landscape design competitions and qualitative enhancement of design quality by mutually comparing the guidelines and entry plans. The case targeted for the current study is landscape design proposals for the Seoul Hangdong Bogeumjari Housing District recently launched within a greenbelt zone in the outskirts of Seoul. The study examines from a critical perspective the design guidelines and the contents of the three winning design proposals with a focus on whether or not they have reflected the guidelines. It was observed that many provisions of the principles and conceptual guidelines which serve as clues to the designs for winning designs proposals show the direction in which the project is to be headed It was also observed that the provisions and the way they are expressed are intertwined, while, at the same time, the guidelines were not organized or developed in an orderly manner. Such a structural pattern of the guidelines is linked to the aspects of the contents of the winning design proposals as described in the following. It is observed that guidelines related to the direction in which the design to be headed are so regulatory and lengthy that they are overly standardized. This could make it difficult to read the possibility of the alternative shifts in the winning design proposals. At the same time, the attributes of winning design proposals themselves, which require observable discriminatory superiority, could serve as a factor causing excess of meanings by jumping on the bandwagon of naming. On the contrary, where autonomy of design is guaranteed or no guidelines are provided for the winning design proposals, discriminatory differences were observed, thereby making it easy to measure them This illustrates well that guidelines and structural format should be provided through a separate undertaking that has taken into careful consideration environmental traits of the site in question, objectives required and so forth.