• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.113-120
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• 2010

Air-cathode microbial fuel cell consisted of 4 unit cells were operated under batch condition and electricity generation and microbial community structure variation were investigated, depending on separator types and cathode characteristics: A) PEM(Proton Exchange Membrane)-30% Wet proofing Carbon Cloth(WC), B) AEM(Anion Exchange Membrane-WC, C) CEM(Cation Exchange Membrane)-WC, D) PEM-No Wet proofing Carbon Cloth(NC). Maximum power densities of PEM-WC, AEM-WC and CEM-WC were 510.9, 522.1 and 504.8 $mW/m^2$, respectively. But PEM-NC showed relatively lower maximum power density of 218.3 $mW/m^2$. And PEM-WC, AEM-WC and CEM-WC showed similar internal resistances(20.0-28.2 ${\Omega}$). PCRDGGE, PCA and diversity indices showed that uncultured bacteria which reported in previous MFC studies were detected in suspended growth bacteria and attached growth bacteria would be affected not by separator type but by cathode characteristic. Thus, cathode characteristic can be one of the critical factors for power generation in air-cathode MFC using PEM, AEM, and CEM as separator.

• 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.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.3
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• pp.55-62
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• 2001

With a spread of BGA, CSP and fine pitch devices, the need of flatter surface finish in bare board is becoming more critical in solderability. The electroless Ni/Au plating has a solution of these needs and also has being spread to apply to surface finish for bare board in many electronic goods. But, the electroless Ni/Au plating had several issues such as Ni oxidation and phosphorous contents. Before this study, we studied on the effect of BGA solderability in electroless Ni/Au plating and chose some major factors such as the oxidation property of NiP plating and warpage of board. Firstly, we made test board with various plating conditions and improved the plating property through the improvement of NiP oxidation reducing P content. Also, we minimized the warpage of board with the improvement of inner layer structure and the analysis of warpage. For the evaluation of solderability, we analyzed the warpage of board and the plating property after mounting BGA on the board with optimizing conditions. The solder joint of BGA is investigated by SEM(Scanning Electronic Microscope) and OM(Optical Microscope). The composition of joint is used by EDS(Energy Dispersive Spectroscopy). We analyzed the fracture strength and mode by ball shear teser.

• Korean Journal of Ichthyology
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• v.25 no.2
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• pp.106-118
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• 2013

Monthly variation in species composition of shallow water fish in Cheonsu Bay were determined using samples collected by a beach seine in the shallow water at Namdang beach from April 2010 to March 2011. The species composition were compared to the data obtained in 1885~86 and in 1993, and factors affecting the long-term change in species composition were analyzed. Fish collected during the study were 25 species, 2,194 individuals and 16,762 g. Chelon haematocheilus were predominated in abundance, accounting 68.5% in the number of individuals. A few number of fish were collected during the cold months from November to April. Abundance was high from July to September by a large catch of juveniles of pelagic fish. Species composition in 1993 did not differ significantly from that in 1985~86 although Fabonigobius gymnauchen living in the fine sediments were increased in abundance. Abundance increase of this gobiid fish was considered to be related to the sedimentation of fine particles due to weakened water circulation after dike construction. The number of species and catch amount in 2010~11 were significantly decreased comparing to those of the former periods; especially in pelagic fish and benthic fish, but C. haematocheilus were greatly increased in abundance. C. haematocheilus is an estuarine fish being able to survive in relatively poor quality of water. This increase seems to be related to fish larvae from the culture net cages recently installed in the inner bay. Recent decrease in abundance of shallow water fish suggested that water quality has been gradually getting poor and recently attained over a critical level for the nursery function of fish.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.239-247
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• 2013

This study is aimed to perform the qualitative evaluation based on the ARCS Model of educational mobile applications for smart phones. The evaluation has been performed targeting 60 students who attending the subject of informational education in 3 different universities in 2012 by allowing them to select the available educational mobile App installed in their smart phone. After, the level of persistent learning-intension from each student and the efficacy of ARCS motivational strategy was measured at learner's perspective. The structural equation model(SEM) was established and analyzed with PLS method to understand the relationship between the ARCS motivational strategy and the persistent learning-intension. The results of the study could be summarized as followings. First, the educational mobile App in various the motivational strategies showed different results that is the highest attention as well as the lowest satisfactory level. Second, the relevance in motivation strategies had the statistically significant effect in attention, confidence, and satisfaction. On the other hand, the other factors of attention, relevance, and confidence showed statistically significant effect in satisfaction. Finally, result demonstrate that the relevance is the critical factor inducing the significant effect in persistent learning-intension among the motivational strategies.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.9
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• pp.31-37
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• 2000

An angular selectivity through the focused readout beam is geometrically analyzed and experimental results are presented. Based on the analysis of geometrical results, we derive a new relation that the angular selectivity depends on incident conditions of the readout beam and independent on the writing conditions. In order to demonstrate our theory, we investigate angular selectivity as functions of following factors: writing beam incident angle, readout beam width and lens focal length. From the experimental results, it is shown that the angular selectivities are 2.632$^{\circ}$, 2.618$^{\circ}$, 2.604$^{\circ}$ when the external half-crossing angles of writing beam are 8$^{\circ}$, 10$^{\circ}$, 14$^{\circ}$, respectively. Applying the same incident angle of the recording beam, angular selectivity is changed by the control of readout beam width and then their properties are 2.632$^{\circ}$, 0.588$^{\circ}$. From these results, we have known that the angular selectivity is very critical to incident conditions of readout beam.

• 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 Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.63-71
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• 2011

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. In this study, we investigated the influence of alkali activator and superplasticizer on the flowability and compressive strength of the alkali-activated mortar in oder to develop cementless alkali-activated concrete using blast furnace slag. In view of the results, we found out that the type and mixture ratio of alkali activator, the type and adding order of superplasticizer results to be significant factors. When cementless alkali-activated mortar using blast furnace slag manufactured with 1:1 the mass ratio of 9M NaOH and sodium silicate, and added superplasticizer before alkali activator in the mixer, we can be secured workability with 180 mm of flow during 1 hours and compressive strength of about 50 MPa under $20^{\circ}C$ curing condition at age of 28days.

• Journal of the Economic Geographical Society of Korea
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• v.13 no.4
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• pp.548-560
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• 2010

This study aims to estimate the payment of farmland reverse mortgage(FRM) and to explore policy considerations about the restructuring of rural area after the initiation of farmland reverse mortgage. Farmland reverse mortgage provides stable monthly income basement for the welfare of rural elderly by liquidating fixed asset such as farmlands which the elderly in rural area owns. The main results of this study can be summarized as follows. First, FRM model based on Housing Equity Conversion Model, which is suggested by Rodda et al (2003), was built. Then, critical factors like farmland value rising rates and interest rates were elaborated, and affordable and proper monthly payment were estimated. 246,982 won, 419,374 won and 757,379 won is given to the borrower at age 65, 75 and 85 respectively with 100,000,000 won value farmland. Second, policy considerations which are necessary for the successful launch of FRM, and restructuring of rural area after launching FRM were discussed. Three policy considerations were proposed. First is about the integrated asset management system for rural elderly people. Second is about the reasonable settlement of corporate farmers system. And third is about the preparations for rural land use planning.

• Sleep Medicine and Psychophysiology
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• v.4 no.2
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• pp.129-139
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• 1997

The data collected to date indicate that sleep-related breathing disorders, including sleep-disordered breathing(sleep apnea) and underlying respiratory system diseases, are one of the important risk factors for cardiovascular dysfunction. Sleep-disordered breathing(sleep apnea) is now recognized as one of the leading causes of systemic hypertension, cardiac arrhythmias, coronary heart disease, pulmonary hypertension, right heart failure, and stroke. Sleep may exert a profound effect on breathing in patients with underlying respiratory system disease including bronchopumonary diseases, chest wall abnormalities, central alveolar hypoventilation syndromes or respiratory neuromuscular disorders. Chronic hypoxia and hypercapnia in these patients may accelerate the development of long term cardiovascular complications such as cardiac arrhythmias, pulmonary hypertension, and right heart failure(cor pulmonale). Several recent studies reported that sleep-related breathing disorders are associated with long-term cardiovascular morbidity and mortality. Careful assessment of respiratory and cardiovascular function in these patients is critical. Aggressive and highly effective treatment of sleep-related breathing disorders using tracheostomy, mechanical ventilation, nasal continuous positive airway pressure therapy(nCPAP), intercurrent oxygen therapy or other interventions can reduce the prevalence of cardiovascular dysfunction and the long-term mortality.