Earticle

The purpose of this study is to provide information necessary for establishing a new strategy for customer service improvement by deriving factors affecting user satisfaction and continuous use intention of mobile app service user characteristics, system characteristics, and social characteristics. The results of this study are summarized as follows. First, reliability, innovation, familiarity, convenience, and self-efficacy among the characteristics of mobile app are analyzed as factors that have the greatest influence on user’s perceived usefulness. Second, convenience, mobility, and visibility are some of the characteristics of mobile app service. Third, identity, security, and expectation agreement among mobile app service characteristics are analyzed as negative factors that do not affect users' perceived usefulness. Fourth, interactivity, familiarity, and self-efficacy among the characteristics of mobile app service were analyzed as positive factors that have the greatest effect on user’s perceived ease of use. Fifth, reliability, mobility, visibility, and convenience among mobile app service characteristics are analyzed as factors that have some positive effects on perceived ease of use of app users. Sixth, identity, innovation, and security among the characteristics of mobile app service are negatively influenced by mobile app users' perceived ease of use. Seventh, the perceived usefulness of mobile app users is analyzed as a factor that has a very positive effect on user satisfaction. Eighth, the perceived ease of use of mobile app users is analyzed as a factor affecting perceived usefulness positively. Ninth, the perceived ease and expectation of mobile app users are positively influenced on user satisfaction. The tenth, the perceived usefulness of the mobile app users was analyzed as a factor having a very positive influence on the persistent intention to use. For the eleventh, the perceived ease of use of mobile app users was analyzed as a factor having a positive effect on the persistent intention to use. The twelfth, mobile app user satisfaction was analyzed as a factor having a very positive effect on the persistent intention to use.

Over the fast few years, web-based e-Learning have made remarkable progress. According to advance of e-Learning, the evaluation of e-Learning effectiveness and success model become more important. This study had a focus on the effect of system characteristic of e-Learning systems and self-efficacy on learning performance. Data has been collected from 192 person experienced in e-Learning. The questionnaire method was adopted to collect the data for this study. The research was conducted by using SPSS 12.0 and AMOS 4.0. The research results and suggestions of the study are as follow. First of all, system quality and information quality of e-Learning system had positive relationship with perceived usefulness. Second, information quality was related positively to user satisfaction. Third, perceived usefulness was positively connected with user satisfaction. Fourth, user satisfaction and self-efficacy had relation to learning performance.

본 논문은 고속철도 채널환경에서의 위성을 통한 Satellite Wibro 시스템의 성능열화특성과 이에 따른 보상기법에 대해 서술하였다. 고속철도 채널환경은 LOS채널 과 터널환경으로 구분되고 LOS 환경에서는 고속철도 파워 급전선에 의한신호블로킹에 의한 문제와 터널내 에서는 Optic Fiber내에서와 같은 다중경로 간섭문제가 발생한다. 이러한 전형적인 두채널 공간에서의 위성 와이브로 시스템 성능열화 특성을 해석적으로 규명하고 컴퓨터 시뮬레이션을 통하여 확인 하였다. 아울러 300 km/h 이상으로 이동하는 고속철도에서 발생되는 OFDM 시스템의 도플러 효과에 의한 ICI 현상과 이를 보상할수 있는 기법을 해석적 ,실험적 결과를 통하여 증명하였다.

In this paper, we describe the performance degradation of satellite Wibro system and compensation method in the high-speed railroad channel environment. High-speed railroad channel environment is divided into LOS channel and tunnel. In the LOS channel, signal blocking caused by railroad power feeder structures can be a critical problem which is can be solved with antenna diversity. On the other hand, multi path interference phenomenon, representable by propagation model of Optic Fiber, occurred in the tunnel may be another obstacle. These satellite Wibro system performance degradations in railroad channel environment are addressed and dequate compensation methods are proposed and verified through computer simulation. In addition, the ICI caused by Doppler shift in OFDM system is analyzed with its compensation method.

This paper deals with numerical analysis on a high-Tc superconducting (HTS) electrodynamic suspension (EDS) simulator according to the variation of the ground conductor conditions. Because the levitation force of EDS system is formed by the magnetic reaction between moving magnets and fixed ground conductors, the distribution of the magnetic flux on a ground conductor plays an important role in the determining of the levitation force level. The possible way to analyze HTS EDS system was implemented with 3D finite element method (FEM) tool. A plate type ground conductor generated stronger levitation force than ring type ground conductor. Although the outer diameter of Ring3 (335 mm) was larger than that of Ring2 (235 mm), the levitation force by Ring2 was stronger than that by Ring3. Considering the results of this paper, it is recommended that the magnetic flux distribution according to the levitation height and magnet current should be taken into account in the design of the ground conductors.

Hydrogen is an eco-friendly energy source and is being actively researched in various fields around the world, including mobility and aerospace. In order to effectively utilize hydrogen energy, it should be used in a liquid state with high energy storage density, but when hydrogen is stored in a liquid state, BOG (boil-off gas) is generated due to the temperature difference with the atmosphere. This should be re-condensed when considering storage efficiency and economy. In particular, large-capacity liquid hydrogen storage tank is required a gaseous helium circulation cooling system that cools by circulating cryogenic refrigerant due to the increase in heat intrusion from external air as the heat transfer area increases and the wide distribution of the gas layer inside the tank. In order to effectively apply the system, thermo-hydraulic analysis through process analysis is required. In this study, the condenser design and system characteristics of a gaseous helium circulation cooling system for BOG recondensation of a liquefied hydrogen storage tank were compared.

As wireless power transfer (WPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly in the contactless EV charging system. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUWPT4EV) system. As the HTS coil has an enough current density, it can deliver a mass amount of electric energy in spite of a small scale antenna. The SUCPT4EV system has been expected as a noble option to improve the transfer efficiency of large electric power. Such a system consists of two resonator coils; HTS transmitting antenna (Tx) coil and normal conducting receiver (Rx) coil. Especially, the impedance matching for each resonator is a sensitive and plays an important role to improve transfer efficiency as well as delivery distance. In this study, we examined the improvement of transmission efficiency and properties for HTS and copper antennas, respectively, within 45 cm distance. Thus, we obtained improved transfer efficiency with HTS antenna over 15% compared with copper antenna. In addition, we achieved effective impedance matching conditions between HTS antenna and copper receiver at radio frequency (RF) power of 370 kHz.

In this study, an analysis and design for hydraulic control system was developed. By using this system, the operator is able to simulate dynamic performance of the system without possessing special knowledge of software or control engineering. A graphical user interface was adopted in the system and all speration for simulation can be done by using window facilities on the display. The electro-hydraulic servo system is simulated to present the performances of the program and compared with the result of Matlab and experiment.

On this study, we operated the dynamic response for impact load of impact absorbing system for spreader by the finite element analysis and showed respectively the spring constant and the damping coefficient which the reaction force by impact was the lowest value for three types impact absorbing system according to the change of system, also we presented the change of impact reaction force according to the spring constant and the damping coefficient. Additionally, among the three types impact absorbing system according to the change of system, the reaction force of model II was the lowest value and the next model which has higher value than model II was model Iand model III has the highest value in the three types.

본 연구는 인터넷의 폭넓은 보급과 더불어 최근 중요성과 이용률이 크게 신장되고 있는 모바일인터넷을 기반으로 하는 모바일커머스의 특징과 현황을 분석해보고 막대한 산업파급력과 경제적효과를 가지고 있음에도 불구하고 발생하는 장애요인과 이를 극복활 수 있는 방안을 제시하고자 한다. 따라서 본 연구는 우선 모바일인터넷과 모바일커머스의 개념을 명확히 이해하는 것을 우선으로 하였으며 아울러 모바일커머스의 특징을 기술적, 비즈니스적, 고객적 차원에서 분석하였다. 가급적 최근의 실질적 데이터나 현황을 파악하고자 현행 이동통신사의 내부 자료를 수용하여 활용하였다. 본 연구를 통해서 모바일커머스가 안정된 상거래 시스템으로 정착되기 위해서는 아직은 풀어야할 과제가 다양한 부분에 산재해 있음을 알 수 있다. 기술적인면을 물론이고, 정책적인면이나 고객의 이해와 의지도 매우 중요한 것으로 나타났다. 그러나 인터넷 이용환경은 빠른 속도로 무선 환경으로 바뀌어 가고 있다. 더불어 인터넷을 통한 전자상거래 역시 큰 폭으로 성장하고 있음은 부인할 수 없는 사실이며 무선과 전자상거래의 접목으로 이루어지는 모바일커머스 역시 정보화사회에서 요구되어지는 당연한 귀결로 보인다.

The purpose of this study is to analyze characteristic of mobile commerce based on mobile internet and diagnose obstacles and suggest promotional plans in terms of for mobile commerce. First of all, this study defines the concept of mobile internet and mobile commerce as on, and then analyzes the characteristic and the status quo of mobile commerce in the aspect of technology and business and customer. In conclusion this study there are many problems to overcome to expand mobile commerce environment. However, the environment of internet is moving from online to wireless and the volume of e-commerce through internet is growing rapidly. Thus, mobile commerce will be a matter of course in information society.

탄산염 균열 저류층인 캐나다 Grosmont 층은 약 4,065억 배럴의 비튜멘이 부존되어 있다. Grosmont 저류층은 불균질 한 균열 발달로 다양한 크기의 매질이 혼재되어 있는 특성을 가진다. Grosmont 층에 대한 기존 SAGD 시뮬레이션은 이원공극 모델과 이원투과도 모델이 적용되고 있다. 이 연구에서는 스팀주입에 따른 균열 내 현상을 반영한 균열시스 템 특성변수를 고려하여 시뮬레이션을 수행하였다. 그 결과 이원투과도 모델에서는 영향이 미미하였으나 이원공극 모델에서는 균열시스템 특성변수에 따라 큰 차이를 보였다. 이원공극 모델에서 균열시스템 특성변수에 따른 최적 예 비가열 기간을 도출하고 SAGD 생산 시뮬레이션에 미치는 영향을 분석하였다.

The OOIP (original oil in-place) of bitumen in fractured carbonate reservoir of Grosmont, Canada is estimated at about 406.5 billion barrels. The Grosmont reservoir is characterized as various matrix sizes due to heterogeneity in fracture density. SAGD simulations for the Grosmont Formation have been based on the dual porosity and dual permeability model. In this study, characteristic variables for fracture system are considered to reflect the mechanism in fracture due to steam injection. The result shows that the characteristic variables play important role in dual porosity model, while trivial in dual permeability model. The effect of the characteristic variables for fracture system has been investigated in terms of the optimal preheating period, recovery factor, and cSOR.

Recently the information system introduction and the application which use the computer are increasing. The efficient operation of information system helps corporations to improve productivity, customer service and corporate competitive power. SaaS(Software as a Service), which is the developed type of outsourcing in the area of information technology, is to use standardized and packaged application by hosting from the outside of enterprise. SaaS is not developed yet as much as people's interest about that in the initial stage, but its related technology and service capacity are accumulated after repeated trial and error, and it's ready to activate the industry. In the area of information system, studies on the measurement of service quality were followed. But there is little study on service quality measurement in the field of SaaS(Software as a Service). The purpose of this study was to divides the SaaS with e-SERVQUAL and it consider the relationship with the perceived recognition and the usage intention. According to this, variables of traditional research were rejected because SaaS is not developed yet in Korea. But information had a strong effect on perceived recognition. Therefore, business related with in SaaS must have provided a correct information about various applications.

A new approach to the critical speed calculation of general multi-mesh gear chain system included bevel gear is presented. A transfer matrix mode! based on Hibner's branch method is developed and the natural properties of the branched rotor system are calculated with using the ${\lambda}$-matrix formulation. A Campbell diagram, in which the excitation sources caused by the mass unbalance of the rotors, misalignment and the transmitted errors of the gearing are considered, shows that, at the neighborhood of the operating speed, there are the two critical speeds amplifying the first mode and the eighth mode.

국내에 분포하고 있는 자연정화시설은 주로 석탄광에서 나오는 갱내수를 처리하기 위해 사용되고있으며 일반적으로 알칼리도 공급 시스템(Successive Alkalinity Producing System, SAPS), 산화·침전조, 소택지등으로 구성된다. 본 연구에서는 와룡, 동해6갱, 호남광업소의 자연정화시설 반응조에서 침전되는 슬러지의 기본적인 특성을 파악하고자 물리·화학적 분석을 수행하였다. 알칼리도 공급 시스템 슬러지의 함수율은 약 50~72% 으로 나타났고, 산화·침전조의 함수율은 59~73%로 나타났다. 입도분석 결과 슬러지의 입도가 다양한 것으로나타났으며, XRF 분석 결과 대부분 슬러지에서 Fe2O3의 함량이 전체에서 70% 이상을 차지하였다. 슬러지에대한 ICP-OES 분석 결과 Cd의 농도가 토양오염기준치를 초과하였다.

Passive mine water treatment system was used for the treatment of the mine water, and consisted of SAPS(Successive Alkalinity Producing System), OP(Oxidation/settling Pond) and wetland, etc. This study was carried out for physical and chemical analysis of sludges of Waryong, Donghae (6th adit) and Honam mine to investigate the basic properties of the sludges settled in the passive mine water treatment system. The water content of the sludges collected from SAPS was found to be about 50% to 72% and that of the sludges collected from OP was found to be about 59% to 73%. The particle size of sludges was various. From the XRF analysis, the content of Fe2O3 was over 70% at most sludges. The Cd concentration of sludges from the ICP-OES analysis exceeded the soil contamination standards of the heavy metals.

The purpose of this study is to understand a information technology acceptance model and to test empirically using field survey. In order to achieve this purpose, first of all, I examined literature reviews about the theory of reasoned action(TRA), the theory of planned behavior(TPB), and the theories of technology acceptance model(TAM). Based on literature reviews, I proposed a technology acceptance model and empirically verified it through using field survey. As a result of, this study was designed to predict and to explain the factors of affecting reuses of a website. The data that were surveyed 193 users of internet were analyzed with SPSS 12.0 and AMOS 4.0. The major results of this study as follows : First, the perceived complexity is influenced by the skill & experience and the quality of system. Second, the quality of system affects the perceived usefulness. Third, the perceived complexity affects the perceived usefulness and the perceived playfulness. Fourth, reuses of a web site are influenced by the perceived usefulness and the perceived playfulness. Finally, the quality of system affects the perceived usefulness and the skill & experience affect the perceived playfulness.

The FPCB is used for electronic products such as LCD display. The process of manufacturing FPCB includes a cutting process, in which each single FPCB is cut and separated from the panel where a series of FPCBs are arrayed. The most-widely used cutting method is the mechanical punching, which has the problem of creating burrs and cracks. In this paper, the cutting characteristics of the FPCB have been experimented using Nd:YAG DPSS UV laser as a way of solving this problem. To maximize the industrial application of this laser cutting process, test samples of the multilayered FPCB have been chosen as it is actually needed in industry. The cutting area of the FPCB has four different types of layer structure. First, to cut the test sample, the threshold laser cut-off fluence has been found. Various combinations of laser and process parameters have been made to supply the acquired laser cut-off fluence. The cutting characteristics in terms of the variation of the parameters are analyzed. The laser and process parameters are optimized, in order to maximize the cutting speed and to reach the best quality of the cutting area. The laser system for the process automation has been also developed.

In this study, the static and the dynamic characteristics of the load-sensitive hydraulic pump control systems of a hydraulic excavator were analyzed using the developed analysis tool. The results were compared with the experimental ones. To improve the static performance of the system, the system parameter effects on the controllable region and the pump pressure variation were studied. The parameters enhancing dynamic characteristics were also considered.

본 논문에서는 태양광과 풍력을 조합한 하이브리드 발전시스템을 이용하여 승압 쵸퍼와 PWM (pulse width modulation) 전압형 인버터인 전력변환기로 구성하였고, 또한 PWM 전압형 인버터는 태양전지가 연속 발전할 수 없는 단점을 보완하기 위해 일반 상용전원과 연계하고 에너지저장장치 (ESS; energy storage system)를 상시 운영하여 공항의 기상 변화에 따른 파장별 LED 항공 유도등을 효율적으로 운용하는 시스템을 구성 하였다. 태양전지에 대한 특성 해석과 수학적 모델링을 통한 시뮬레이션을 행하여 태양전지 특성 사양과 비교하였고, PWM 전압형 인버터와 위상동기를 위해서 계통전압을 검출하여 계통전압과 인버터 출력을 동상 운전하므로 잉여전력을 계통과 연계할 수 있게 하였으며 공항의 활주로, 항공 유도등에 적용하여 양호한 동특성을 얻을 수 있는 제어회로를 동시에 개발하여 항공유도등의 다양성을 추구할 수 있음을 확인 하였다.

In this study, the system was composed of the booster chopper and the power converter, which is a pulse width modulation (PWM) voltage inverter using a hybrid power generation system solar cell energy and wind force, Furthermore, in order to compensate the PWM voltage type inverter was linked with the general commercial power source, and through a normal operation of energy storage system (ESS), the system operated the LED Taxi Light by Wavelength according to Meteorological Changes at the airport in an efficient manner. The performance of the system was compared with the solar cell characteristics specification. In addition, for phase synchronization with the PWM voltage type inverter, the grid voltage was detected so as to operate the grid voltage and inverter output in the same phase and to connect the surplus electric power with the system. Finally, by developing a control circuit at the same time from which an excellent dynamic characteristics can be obtained through applying to the airport runway taxi light, it was concluded that a variety of taxi light can be pursued.

광산배수의 계절에 따른 수질 변화와 자연정화시설의 정화효율을 파악하기 위하여 강원도 평창군 소재 한창탄광에서 광산배수, 폐석침출수, 샘물 및 각 처리공정별 처리수에 대한 시료채취와 분석이 수행되었다. 또한 SAPS(Successive Alkalinity Producing System)에서의 황산염환원 반응여부를 인지하고자 황동위원소 조성분석이 수행되었다. 한창탄광의 갱구유출수는 6.5 이상의 pH를 유지하지만 Fe와 SO42-의 농도가 증가되는 경향을 갖는다. 부근 하천수의 수질은 석축침출수에 주로 영향을 받으며 유량의 변화에 따라 영향정도가 달라진다. 샘물은 pH 3.29∼4.57의 산성수이며 높은 Al과 SO42- 농도를 보인다. 샘물의 동위원소조성과 화학조성으로 볼 때 지하수의 수질에 영향을 미치는 것은 부근에 방치된 폐석의 산화에 의한 것으로 판단된다. SAPS의 산도 제거율은 평균 16.65 CaCO3 g/m2/day이며 Fe 제거율은 평균 12.08g/m2/day이다. 그러나 SO42- 농도가 거의 줄어들지 않고 황동위원소 조성의 변화도 거의 나타나지 않아 미생물에 의한 황산염환원이 일어나지 않거나 매우 약한 것으로 보인다. 또한 SAPS와 호기성소택지에서의 산도제거율은 겨울철에 매우 불량한 것으로 나타났다.

Sampling of waters from each stage of the passive treatment system, waste rock pile seepage, and spring near the Hanchang coal mine of Kangwon Province were carried out seasonally and analyzed to evaluate the hydro-characteristic variation of mine drainage and the removal efficiency of the passive treatment system. Sulfur isotope compositions were measured to identify the sulfate reduction processes in the SAPS (Successive Alkalinity Producing System). The mine drainages from the Hanchang mine adit showed pH higher than 6.5 at all seasons but continuously increasing iron and sulfate concentrations. Spring waters near the mine were acidic(pH 3.29 ~ 4.57) and showed high concentration of aluminum and sulfate. The sulfate isotope and chemical composition of spring water implied that the oxidation of waste rock be the main factor which govern the quality of groundwater in the vicinity of the Hanchang mine. The acidity removal efficiency in the SAPS was 16.65g/m2/day as an average and the iron removal efficiency was 12.08g/m2/day as an average. However, no appreciable decrease of sulfur content and almost similar sulfur isotope compositions of water from each stage of the treatment system might suggest incomplete or very poor microbiological sulfate reduction. Also the acidity removal efficiencies of the SAPS and aerobic wetland decreased during the winter.