• Journal of KIISE
• /
• v.42 no.6
• /
• pp.769-780
• /
• 2015

Smoothing a digital curve by averaging its connected points is widely employed to minimize sharp changes of the curve that are generally introduced by noise. An appropriate degree of smoothing is critical since the area or features of the original shape can be distorted at a higher degree while the noise is insufficiently removed at a lower degree. In this paper, we provide a mathematical relationship between the parameters, such as the number of iterations, average distance between neighboring points, weighting factors for averaging and the moving distance of the point on the curve after smoothing. Based on these findings, we propose to control the smoothed curve such that its deviation is bounded particular error level as well as to significantly expedite smoothing for a pixel-based digital curve.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.35 no.8
• /
• pp.353-362
• /
• 1986

This paper shows that 6 pulse converter instead of 12 pulse converter can be used for the control of Superconducting Magnet Energy Storage(SMES) to improve the stability and to suppress the voltage fluctuation of power system. In order to prevent the commutation failure, when 6 pulse converter used for simultaneous control of real power and reactive power is asymmetrically controlled, stable control region has been presented by analyzing the commutation phenomena at critical points which distinguish the stable control region from the unstrol control region. Harmonic components of line current and output voltage have been calculated. Finally, computer simulation of power system stabilization has been presented to show the effectiveness of the proposed method. According to the computation results, SMES controlled by the 6 pulse converter is an effective measure in reducing the oscillation and the transient instability of the power system.

• The Korean Ginseng Research and Industry
• /
• v.13 no.1
• /
• pp.3-10
• /
• 2019

• Korean journal of food and cookery science
• /
• v.27 no.2
• /
• pp.61-71
• /
• 2011

This study was conducted to estimate the shelf-life of Kimbab manufactured using a Hazard Analysis and Critical Control Point (HACCP). We performed a microbiological verification after applying the HACCP plan to Kimbab. Additionally, the shelf-life of Kimbab at each holding temperature was calculated as a regression equation between the aerobic plate counts and holding time during the storage period. The critical control points of the HACCP plan, that were applied to Kimbab, included: cold-holding of refrigerated foods, checking the endpoint cooking temperature of heated food, and cold-holding of cooked foods. As a result of the microbiological verification of Kimbab, the aerobic plate counts averaged 3.46 log CFU/g. In contrast, the coliforms, E. coli, Staphylococcus aureus, and Salmonella spp. were not detected in any of the samples. The estimated shelf-life of Kimbab was calculated to be 45 hours at $10^{\circ}C$, 29 hours at $15^{\circ}C$, 6 hours at $25^{\circ}C$ and 3 hours at $35^{\circ}C$. In conclusion, manufacturers should apply a prerequisite program and a HACCP system for a safe consumption of ready-to-eat foods and label products with a proper shelf-life. Distributors should control the proper holding time-temperature until sale and consumers should eat immediately after purchasing ready-to-eat foods.

• Journal of the Korean Society of Food Culture
• /
• v.10 no.1
• /
• pp.35-44
• /
• 1995

A hazard analysis which included watching operations, measuring temperatures of foods throughout preparation and display, and sampling and testing for microorganisms of total plate counts and coliform bacteria was conducted in various phases of product flow of Korean soups (Galbitang, Sullungtang, Jangkuk) prepared at Korean restaurants. Cooked foods were sometimes held at room temperature long enough to permit multiplication of bacteria that might have been present. This was confirmed by the finding of large numbers of aerobic mesophilic colonies ($10^6$) in samples of such foods after handling and holding for several hours before served. These bacteria decreased down to $10^1{\sim}10^2$ while the contaminated Tang were served. And internal temperature of Tang served was approximately $70^{\circ}C$. Critical control points identified were, pre-preparation, handling after cooking and holding on display. Guidelines were suggested for effective quality control of Tang (Korean soups) production. Handlers of these foods need to be informed of the hazards and appropriate preventive measures.

• Korean journal of food and cookery science
• /
• v.8 no.2
• /
• pp.123-135
• /
• 1992

Time and temperature conditions, and microbiological qualities of six categories of menu items were assessed according to the process of food product Row in a 500 bed general hospital. The Harzard Analysis Critical Control Point (HACCP) system was applied to determine harzards, to assess their severity and risks, and to identity CCPs and memos for monitoring mem. The Critical Control Points identified for each category of menu items were: Meat Soup (Kyung Sang Do Gogi Guk): Pre-preparation, holding after pre-preration, and holding after cooking; Pot Stewed Stuffed Cabbage (Soe Yangbaechu Mali Chim): pre-preparation, holding after Pre-preparation, stuffing, cooking and holding after cooking; Boned Pork Sour Salad (Doeji Suyuk Muchim): Pre-preparation, holding after pre-preparation, and post-preparation after cooking; Sauteed Pork Ball (Jeyuk Wanja Jon): pre-preparation, holding after pre-preparation, shaping, and holding after cooking; Stir-fried Fragrant Mushroom (Pyogo Bosot Bokkum): basic ingredients, Pre-preparation, holding after pre-preparation, and holding after cooking; and Fried Corn with Vegetables (Oksusu Yachae Tuigim): pre-preparation, holding after pre-preparation, mixing, and holding after cooking.

• Journal of IKEEE
• /
• v.21 no.1
• /
• pp.81-84
• /
• 2017

As the demands for offshore wind power generation systems on a large scale have grown dramatically, and extensive developments in PMSG (Permanent Magnet Synchronous Generator) and DFIG (Doubly-fed Induction Generator) wind turbine system have been going on. However, the wind power systems have been more sophisticated, and their reliability becomes critical issues. Averagely, wind turbines have shut down for about a week per year for repairs and maintenance. Especially the high speed gearbox of DFIG is inevitable components for high power generation, but becomes one of the critical failures. In this paper, a new reliable gearless wind turbine structure is proposed. The gearless wind turbine can operate on a maximum power points by controlling the speed of a rotational stator. The proposed approach is verified by PSIM simulations, resulting in increased energy reliability.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.3
• /
• pp.21-28
• /
• 2015

As film products are increasingly used in a wide range of areas, from producing traditional flexible packaging to high-tech electronic products, a higher level of quality is demanded. Most film products are made in the form of rolled finished goods, therefore, various quality issues related to their shape characteristics must be addressed. The thickness of the film products is one of the most common and important critical-to-quality attributes (CTQs). Particularly, the degree of thickness uniformity is more important than other thickness parameters, because it will be potential causes of many secondary thickness-related quality problems, such as wrinkles or faulty windings. To control the degree of thickness uniformity, the fixed bending region is oneof the most important CTQs to manage. Fixed bending regions are special points in the transverse direction of a rolled product with consistent minute variations of the thickness gap. This paper describes the measurement and analysis of thickness uniformity data, which were performed in a real manufacturing field of biaxial oriented polypropylene (BOPP) film. In previous researches, quality function deployment (QFD) or fault tree analysis were used to find the most critical process attributes out to controlthe CTQ of thickness uniformity. Whereas, this paper uses traditional control charts to find the most critical process attributes out in this problem. In addition, the selection of one of the major critical process attributes (CTPs) that is expected to affect the CTQ of thickness uniformity is also described. The selected critical-to-process attributes are the controlled temperatures along the transverse direction. A dramatic improvement in thickness uniformity was observed when the selected CTPs were controlled.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.1
• /
• pp.22-28
• /
• 2018

In case of developing a combined system by a number of distributed resources with storage device, a number of application suggests a huge capacity can derive operational flexibility both power supply issues or when unexpected situation imposed. However, it is important to determine a resonable energy capacity because the device have many controversial cost issues in current power system industry. An ESS application which focusing essentially required points can induce appropriate storage capacity that required in economic operation. In this paper, a curtailment supporting algorithm based on storage device is introduced, and applied in the capacity calculation method. The main algorithm pursues handling minor exceeding quantities which can cause mechanical load at blade; This paper tries to include it for configuring hybrid algorithm with pitch control. Several fluctuating conditions are utilized in simulation to reflect critical situation. The analyzing process focuses on the control feasibility with applied capacity and control method.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1000-1007
• /
• 2007

Recently, many critical control systems are developed using formal methods. When software applied to such systems is developed, the employment of formal methods in the software requirements specification and verification will provide increased assurance for such applications. Earlier error of overlooked requirement specification can be detected using formal specification method. Also the testing and full verification to examine all reachable states using model checking to undertake formal verification are able to be completed. In the comparison of other formal specification methods, we choose the Z formal language for applying to the train control system. Using Z is able to realize higher correctness in the requirement specification, and we propose the Statemate of the best solution in formal verification tools for the system modeling and verification. The Statemate makes it possible to prove thoroughly the system execution from the simple graphical modeling of the complicated train control system. Then we can expect that the model-based formal method combining Z with Statemate will be utilized widely for the railway systems due to various strong points.