• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.532-534
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• 1994

In this paper, the program for the train operation from the train characteristics and motion equation is presented. By the decision of the operation condition, the computation system for train operation(CSTO) can be developed successively. As some applications, the computation examples of the rheostatic- and the inverter-train are demonstrated.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.107-112
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• 2005

When it comes to automatic operation control of urban rail vehicle, a PID control makes it run between stations within the fixed time and stop exactly at the stop sign on the platform, satisfying jerk limit. An optimal control is applied to automatic operation performance control to minimize energy consumption while the urban rail vehicle satisfies automatic operation condition on this paper. The control performance in terms of energy minimization along with the constraint on precision stops is compared between the optimal control and PID control.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.23-30
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• 2008

As a basic machining process, turning is a widely used machining process in which a single-point cutting tool removes material from the surface of a rotating material. A common method of evaluating machining performance is to measure the surface roughness. In a turning operation, it is important to select cutting conditions for achieving high cutting performance. As a rule, cutting conditions can be classified into feed rate, depth of cut and insert radius. While cutting process even though cutting conditions are optimized, the average roughness can be deterioration due to wear of the cutting tool edge. In this study, the aim is to maintain the average roughness even though the cutting condition is irregularly changing within the predictable range due to the working environment. First, the surface roughness model influenced by cutting conditions is constructed based on the experimental results in a turning operation, Second, applying the sliding mode control theory to the turning operation model which is composed of the surface roughness model and the motor transfer function, the surface roughness is closed to the desired value. Finally, the effectiveness of this approach is demonstrated through the computer simulation.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1109-1115
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• 2023

The shell and tube-type heat exchanger was the most utilized in industrial field because of its simple structure and wide operation conditions and so on. This study was performed to investigate the characteristics of behavior of thermal flow according to operation condition of small-sized shell and tube-type heat exchanger. The operation conditions, here, were set up to flow rate of hot air with temperature of 100℃, number of baffle and cut rate of baffle(BCR) using numerical analysis. As the results, both mean relative pressure and relative pressure drop was increased with quadratic curve in case of less than BCR 25%, however, decreased linearly in case of more than BCR 25%. The collision with first baffle by flow velocity and temperature, of hot air, respectively, was depended on BCR. Further it showed that the behaviors between flow velocity and temperature were almost similar.

• The Journal of the Korean dental association
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• v.54 no.8
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• pp.613-629
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• 2016

This study assayed regional distribution of dental hospital & dental clinics, the number of population & households per one dental hospital & clinic, operation condition & duration. This study used public data that display from 1946 years(the first dental clinic open in republic of korea) to 2016 years. We collected present condition of 21,686 dental hospital and clinics available in public data portal site on 28. Feb.2016. Data were classified by scale, location, permission year, operation duration of dental hospital & clinics and were analyzed using SPSS 20.0 program. Surveyed on Feb. 2016. Best top 10 regions of permission dental clinics are (1) Gangnam-gu, Seoul(1,337), (2) Seongnamsi, Gyeonggi-do(555), (3) Songpa-gu, Seoul(491), (4) Yeongdeungpo-gu, Seoul(472), (5) Suwon-si, Gyeonggi-do(443), (6) Seocho-gu, Seoul(428), (7) Nowon-gu, Seoul(417), (8) Goyang-si, Gyeonggi-do(413), (9) Jung-gu, Seoul(380), (10) Yongin-si, Gyeonggi-do(353). Whereas best top 10 regions of operating dental clinics are (1) Gangnam-gu, Seoul(581), (2) Seongnamsi, Gyeonggi-do(415), (3) Suwon-si, Gyeonggi-do(382), (4) Seocho-gu, Seoul(320), (5) Changwon-si, Gyeongsangnam-do(303), (6) Songpa-gu, Seoul(295) (7) Goyang-si, Gyeonggi-do(290), (8) Bucheon-si and Yongin-si, Gyeonggi-do(262), (9) Jeonju-si, Jeollabuk-do(224). Average population per one dental hospital & clinic by regional local government are 3,120 people. Best five region of population per one dental hospital & clinic are (1) Sejong-si(5,272), (2) Gangwon-do(4,653), (3) Chungcheongbuk-do(4,513), (4) Gyeongsangbuk-do(4,490), (5) Chungcheongnam-do(4,402). Average households per one dental hospital & clinic by regional local government are 1,316 households. Best three region of households per one dental hospital & clinic are (1) Sejong-si(2,126), (2) Gangwon-do(2,057), (3) Gyeongsangbuk-do(1,946). From 1946 to 1986, permission and operating dental hospital and clinics was steadily increasing. On 1986-1990, 1991-1995, permission, operation and closure of dental hospital and clinics increase rapidly. From the 2011-2015 to 2016(present), permission, operation and closure of dental hospital and clinics is decreasing. Average operating duration of closured dental hospital and clinics are 14.054 years. We need to map of dental hospital and clinics for open and operation of one, base on analyzed results. In an era of 30,000 dentist, we should to be concerned about operation of dental clinics in the light of past operating condition.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.403-407
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a greenhouse culture facility for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex in Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• New & Renewable Energy
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• v.1 no.2 s.2
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• pp.53-59
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a green-house culture facility for reducing healing cost, Increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex In Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely Investigated by changing the control condition based on the temperature difference which Is the most important operating parameter For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, It is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.38-39
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• 2017

This paper proposes a new control method for an AC-DC Buck converter which is utilized as a front-end converter of a 2-stage high power density adapter. In the conventional adapter applications, 2-stage configuration shows higher power transfer efficiency and higher power density than those of the single stage flyback converter. In the 2-stage AC-DC converter, the boost converter is widely used as a front-end converter. However, an efficiency variation between high AC line and low AC line is large. On the other hand, the proposed conduction band control method for a buck front-end converter has an advantage of small efficiency variation. In the proposed control method, switching operation is determined by a band control voltage which represents output load condition, and an AC line voltage. If the output load increasesin low AC line, the switching operation range is expanded in half of line cycle. On the contrary, in light load and high line condition, the switching operation is narrowed. Thus, the proposed control method reduces switching loss under high AC line and light load condition. A 60W prototype which is configured the buck and LLC converter with the proposed control method is experimented on to verify the validity of the proposed system. The prototype shows 92.16% of AC-DC overall efficiency and 20.19 W/in 3 of power density.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.441-444
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• 1997

This paper describes the bending traveling-wave type ultrasonic motor which generates the traveling wave by combining two standing waves with phase difference time and space. In +2$0^{\circ}C$~3$0^{\circ}C$, the operation characteristic of USM has represented normal condition. But in the other temperature, the operation characteristic of USM has abnormal condition, that is driving frequency, drive current and r.p.m are down. The recent USM has controller without temperature compensation. This study aimed at fuzzy controller which must follow the frequency at operation temperature and then r.p.m and torque increased.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.971-974
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• 1987

Considering heat transfer and heat loss processes for the heat engine operating between two fixed heat reservoirs, it may be qualitatively explained that the maxima of power output and its efficiency depending upon operating conditions are extreme maxima. Furthermore, it is also found that from an economic point of view the above two extremes are related to extreme minima of plant cost per unit power output and operation cost per unit power output respectively, and the condition of minimum cost per unit power output exists between the extreme minimum conditions of plant cost per unit power output and that of operation cost per unit power output.