• Journal of Information Management
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• v.28 no.1
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• pp.34-61
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• 1997

This study suggests that the model of electronic document delivery service be carried out by academic libraries step by step, based on the analysis of the domestic and foreign status. The model consists of the user's request step, electronic document building step, electronic document transferring step. Academic libraries should perform the electronic document delivery service step by step that satisfies user's information need.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.5
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• pp.217-225
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• 2005

In a power system, an out-of-step condition causes a variety of risk such as serious damage to system elements, tripping of loads and generators, mal-operation of relays, etc. Therefore, it is very important to detect the out-of-step condition and take a proper measure. Several out-of-step detection methods have been employed in relays until now. Most common method used for an out-of-step detection is based on the transition time through the blocking impedance area in R-X diagram. Also, the R-R dot out-of-step relay, the out-of-step prediction method and the adaptive out-of-step relay using the equal area criterion (EAC) and Global Positioning Satellite (GPS) technology have been developed. This paper presents the out-of-step detection algorithm using the time variation of the complex power. The complex power is calculated and the mechanical power of the generator is estimated by using the electrical power, and then the out-of-step detection algorithm which is based on the complex power and the estimated mechanical power, is presented. This algorithm may detect the instant when the generator angle passes the Unstable Equilibrium Point (UEP). The proposed out-of-step algorithm is verified and tested by using Alternative Transient Program/Electromagnetic Transient Program (ATP/EMTP) MODELS.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.111-118
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• 2011

Single-layer latticed domes with rigid-joint have an advantage in the construction cost and the aesthetic. But, in single-layer latticed domes, the joints are hard to discriminate between pin-joint and rigid-joint, and consisted of semi-rigid joint in practical. And the erection of large roof structures requires special techniques. As one of these special techniques is the Step-Up erection method. This paper verified buckling characteristics of single-Layer lamella domes according to the Joint flexibility under construction by Step-up method. The results are follows: As erection steps increase, the buckling strength decreases. It is occurred the joint buckling by snap through on the top of dome when the joint flexibility close the rigid. And large tensile stress distribution appeared in circumferential member of bottom boundary when the step of construction is low. As the step of construction increase, large compressive stress distribution showed in the top of dome.

• Journal of Nutrition and Health
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• v.42 no.2
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• pp.158-170
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• 2009

This study was conducted to examine the usefulness of adding final probing step (step3) in dietary assessment by 24-hour recall method among Korean adults. One-hundred fifty five adults (37 males and 118 females) above 30 years of age who visited hospitals for health examination were recruited at three hospitals in Korea. One day dietary intake was obtained using 24-hour recall method from each subject. Dietary interview was conducted in 3 steps, (1) quick list of foods eaten during the previous day, (2) detailed information of all the foods eaten, (3) the final probing for any items forgotten. Items added at the step3 were identified and contributions of energy and nutrient intakes were calculated. The average duration of interview was 10.5 min, and time spent for each step was 4.12 minute for step 1, 5.62 minute for step 2, and 38 second for step 3. The average number of dishes reported by the subjects added at the step 3 was 2.2. (Males = 2.6, Females = 1.6) Frequently reported dishes in the step 3 were Beverage, Tea, alcohol (37.1%) and Fruits (31.8%). From mean total energy intake of 1,589 kcal (Men = 1,846 kcal, Women = 1,509 kcal), 179 kcal (11.3%) was added at the step 3. In the step 3, nutrient intakes increased significantly except retinol in total subjects and except retinol and cholesterol in males but all nutrients increased significantly in females. The final probing step can add significant information on intakes of foods and many nutrients with only about 38 seconds of interview time. Confirmation of the results with larger samples of different age groups is needed.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.566-569
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• 1987

The primary difficulties encountered in the use of step motors are underdamped response when stopping at a specified position and dynamic instability during high-speed slewing. This paper proposes a speed and position detection scheme using the back EMF generated by the rotating permanent magnet field of a two-phase 1.8.deg. hybrid step motor, and presents its application to the state-variable feedback control of the hybrid step motor. All simulation results in a single step response show that the hybrid step motor performances such as peak overshoot and settling time are greatly improved.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.682-689
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• 2015

A two-step process was investigated for pretreatment and fractionation of rice straw. The two-step fractionation process involves first, soaking rice straw in aqueous ammonia (SAA) in a batch reactor to recover lignin-rich hydrolysate. This is followed by a second-step treatment in a fixed-bed flow-through column reactor to recover xylo-oligomer-rich hydrolysate. The remaining glucan-rich solid cake is then subjected to an enzymatic process. In the first variant, SAA treatment in the first step dissolves lignin at moderate temperature (60 and $80^{\circ}C$), while in the second step, hot-water treatment is used for xylan removal at higher temperatures ($150{\sim}210^{\circ}C$). Under optimal conditions ($190^{\circ}C$ reaction temperature, 30 min reaction time, 5.0 ml/min flow rate, and 2.3 MPa reaction pressure), the SAA-hot-water fractionation removed 79.2% of the lignin and 63.4% of the xylan. In the second variant, SAA was followed by treatment with dilute sulfuric acid. With this process, optimal treatment conditions for effective fractionation of xylo-oligomer were found to be $80^{\circ}C$, 12 h reaction time, solid-to-liquid ratio of 1:12 in the first step; and 5.0 ml $H_2SO_4/min$, $170^{\circ}C$, and 2.3 MPa in the second step. After this two-step fractionation process, 85.4% lignin removal and 78.9% xylan removal (26.8% xylan recovery) were achieved. Use of the optimized second variant of the two-step fractionation process (SAA and $H_2SO_4$) resulted in enhanced enzymatic digestibility of the treated solid (99% glucan digestibility) with 15 FPU (filter paper unit) of CTec2 (cellulase)/g-glucan of enzyme loading, which was higher than 92% in the two-step fractionation process (SAA and hot-water).

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.171-179
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• 2002

STEP-NC is the next generation CNC controller taking STEP-based data model as the interface scheme (or language) between CAM and CNC, and carrying out various intelligent functions. At the moment, efforts are being made worldwide to establish international standard for the new interface scheme formalized as ISO14649. As the new language is being established, increasing attention is being paid to the development of the new CNC. Korea STEP-NC is an integrated STEP-NC system taking ISO 14649 as an input, and carrying out various intelligent functions. It is composed of 5 modules: 1) Shop Floor Programming System (PosSFP), 2) Tool Path Generator (PosTPG), 3) Tool Path Viewer (PosTPV), 4) Man Machine Interface (PosMMI), and 5) CNC Kernel (PosCNC). Distinguished from other prototypes (of Europe and USA), the Korea STEP-NC is top-down designed, and bottom-up implemented comprehensively incorporating all the crucial components for realizing the full benefit of STEP-NC paradigm, without using any existing commercial CAD/CAM systems and CNC kernels. The Korea STEP-NC prototype was successfully demonstrated and evaluated in the ISO conventions Together with prototypes of Europe and USA, Korea STEP-NC will be used as a reference system fur the Triangular Conformance Test to be jointly carried out by ISO TC184 SC1, SC4, and IMS Project.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.318-321
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• 1997

This paper is about improving characteristic of plant by using micro-step driver method in 5 phase step motor for satisfying the condition of low oscillation and high accuracy in soldering machine. We choose open loop control method for minimizing hardware system and use one chip microprocessor, power MOSFET nd some device to realize accurate micro-step driver system.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.1
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• pp.65-76
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• 2020

The notion of m-step competition graph was introduced by Cho et al. in 2000 as an interesting variation of competition graph. In this paper, we study the m-step competition graphs of d-partial orders, which generalizes the results obtained by Park et al. in 2011 and Choi et al. in 2018.

• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.165-171
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• 2006

This paper proposes a data fusion algorithm of nonlinear multi sensor dynamic systems of synchronous sampling based on filtering step by step. Firstly, the object state variable at the next time index can be predicted by the previous global information with the systems, then the predicted estimation can be updated in turn by use of the extended Kalman filter when all of the observations aiming at the target state variable arrive. Finally a fusion estimation of the object state variable is obtained based on the system global information. Synchronously, we formulate the new algorithm and compare its performances with those of the traditional nonlinear centralized and distributed data fusion algorithms by the indexes that include the computational complexity, data communicational burden, time delay and estimation accuracy, etc.. These compared results indicate that the performance from the new algorithm is superior to the performances from the two traditional nonlinear data fusion algorithms.