• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.17-18
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• 2008

In this paper, 1%-nitrogen doped Nickel was used for improvement of thermal stability of Ni-Germanide. Proposed Ni-N(1%)/TiN structure has shown better thermal stability, sheet resistance and less agglomeration characteristic than pure Ni/TiN structure. During the germanidation process, it is believed that the nitrogen atoms in the deposited nickel layer can suppress the agglomeration of Ni germanide by retarding the diffusion of Ni atoms toward silicon layer, hence improve the thermal stability of Ni-germanide.

• Journal of Marine Bioscience and Biotechnology
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• v.14 no.2
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• pp.112-123
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• 2022

Photosynthetic bacteria (PSB) play an important role in water purification, and their application is beneficial for sustainable aquaculture. However, maintaining the microbial stability of PSB from subculturing to preservation is a challenging task. Since improvement in the microbial stability of PSB is a crucial parameter, optimized conditions for cell immobilization and lyophilization were investigated. In PSB immobilization, 0.1-M CaCl₂ was found to be the most effective divalent metal ion solution in terms of cost-effectiveness, resulting in beads with a 4-mm diameter and high loading (1.91×10⁹ CFU/mL) of viable cells. Maintenance of cell viability, external appearance, and color of PSB beads was best in 3.5% NaCl during storage. In lyophilization, the addition of skim milk (9%) and dextrose (2%) as cryoprotective additives allowed the highest cell viability. Over an 18-week shrimp breeding period, when optimally manufactured beads and lyophilized powder of PSB were applied to shrimp aquaculture water, NH⁴⁺, NO₃^-, and NO₂^- were more effectively removed by 55%, 100%, and 100%, respectively, compared to controls. Thus, microbial stability of PSB through optimized cell immobilization and lyophilization was successfully enhanced, enabling a wide application.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.2
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• pp.162-171
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• 2019

This study is aimed to develop an improved shellfish dredge vessel considering the increase of the fishing safety and welfare of fishermen in Jeonnam province. We visited five fishing village societies in Korea, and conducted field surveys and survey questions to investigate the current status. In order to solve the problems presented by the investigation, a general arrangement of the improvement vessel was written and adopted after meeting between the fishermen and research team, and calculated the initial stability in five loading conditions by using the Napa program. As a result of field surveys and survey questions, the existing vessel have buoyant materials under the bow and the warp pass through the wheel-house. In addition, most fishing equipment and nets are concentrated on a narrow stern, making it difficult to work efficiently. According to the survey, fishermen also responded that operation of casting and hauling is very inconvenient. The fishing equipment of the improvement vessel was rearranged, the size of the wheel-house and the crew room was increased, and we secured a basic welfare space. As a result of the initial stability test, the stability criteria of the fishing vessel were satisfied in all loading condition.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.1-9
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• 2015

Stability criterion and its calculation are the crucial issue in the application of sail-assisted ship. However, there is at present no specific criterion and computational methods for the stability of sail-assisted ship. Based on the stability requirements for seagoing ships, the stability criterion of the sail-assisted ships is suggested in this paper. Furthermore, how to calculate the parameters and determine some specific coefficients for the ship stability calculation, as well as how to redraw stability curve are also discussed in this paper. Finally, to give an illustration, the proposed method is applied on a sail assisted-ship model with comments and recommendations for improvement.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.543-554
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• 1995

This paper describes the improvement of driving stability and the control system for INMEL-VII which is motorized manual wheelchair to satisfy requirements of the disabled The INMEL-VI was based on high maneuverability of the omnidirection drive and safety But the results of field tests about two years showed some problems to the disabled in daily life such as driving stability, Pm switching noise, and rotation of motor without driving command on negative slope. To solve the problems due to an increased DC motor power and applied to direct connection method in INMEL- VII. It improved the driving circuits and set switching frequency to 5KHz to eliminate the switching noise caused by PWM control of DC motor, As compare with the INMEL-VI, INMEL-VII is improved in driving stability by transfer the weight center to forward. The results of field testing proved the improvement of the driving stability and software algorithm It has been estimated to have a hlgh practical use for powered walking aids to the disabled's daily life.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.153-158
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• 2000

The purpose of present paper is to prove an improvement on stability of plane Journal bearing due to the leaf spring damper(LSD) experimentally A flexible rotor system is designed and manufackuea in order to generate oil whip instability of journal bearing at relative lower rotating speed. Vibration amplitude and instability onset speeds are investigated for a conventional plane journal bearing and plane journal bearing with LSD. To investigate the damping effects of LSD on stability of bearing, experiments are also conducted on the leaf spring dampers with and without working oil. It is found that the leaf spring damper can considerably increase the instability onset speed of a plane journal bearing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.3
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• pp.525-530
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• 2010

Installation of FACTS(Flexible AC Transmission System) device can maximize utilization of existing power facilities and reliability of power system. STATCOM has excellent characteristics in operating cost, maintaining facilities, loss and so on. However, STATCOM has a disadvantage of facility cost over capacity. So it is effective to coordinate STATCOM and existing external bank(capacitor and reactor) and OLTC(On Load Tap Changer). This paper mainly proposes coordinative control method between STATCOM installed within substation and other reactive power resources including Shunt Reactors and Shunt Capacitors and OLTC for voltage stability improvement. The proposed coordinative control method is developed for the STATCOM of Mi-gum substation and the simulation results of EMTP/RV model show the effectiveness of the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.32-41
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• 1995

In the analysis of metal forming processes by the finite element method, there are many numerical instabilities such as element locking, hourglass mode and shear locking. These instabilities may have a bad effect upon accuracy and convergence. The present work is concerned with improvement of stability and efficiency in two-dimensional rigid-plastic finite element method using various type of elemenmts and numerical intergration schemes. As metal forming examples, upsetting and backward extrusion are taken for comparison among the methods: various element types and numerical integration schemes. Comparison is made in terms of stability and efficiency in element behavior and computational efficiency and a new scheme of adaptive directional reduced integration is introduced. As a result, the finite element computation has been stabilized from the viewpoint of computational time, convergency, and numerical instability.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.205-212
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• 2012

This paper proposes the fuzzy logic based variable step-size MPPT (Maximum Power Point Tracking) method for the stability at the steady state and the improvement of the transient response in the wind power system. If the change value of duty ratio is set on stability of the steady state, MPPT control traces to maximum power point slowly. And if the change value is set on improvement of the transient response, the system output oscillates at the maximum power point. By adjusting the step size with fuzzy logic, it can be improved the MPPT response speed and stability at steady state when MPPT control is performed to track the maximum power point. The effectiveness of the proposed method has been verified by simulations and experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.888-893
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• 2000

This experimental study is the improvement of running stability for freight car. KNR (Korean National Railroad)'s conventional wagons, light bodies running on Barber style bogies with 5-1/$2{\times}10$ journals, would be considered fundamentally to be a most difficult car to control above 100km/h. From the results of experiment, to permit high speed operation safely, was realized with the resilient side bearing. Also, equipped with resilient side bearing, and elastowedge friction elements to eliminate bolster wedge pocket wear, KNR's wagons can be secure the running stability with lower maintenance requirements than current experience.