• Speech Sciences
• /
• v.8 no.3
• /
• pp.31-41
• /
• 2001

This paper aims to provide preliminary evidence that (at least part of) phonetic phenomena are not simply automatic or arbitrary, but are explained by the functional guidelines, ease of articulation and maintenance of contrasts. The first study shows that languages with more high vowels (e.g., French) allow larger consonantal deviation from its target than languages with less high vowels (e.g., English). This is interpreted as achieving the economy of articulation to a certain extent in order to avoid otherwise extreme articulatory movement to be made in CV syllables due to strict demand on maintaining vocalic contrasts. The second study shows that Russian plain bilabial consonant allows less amount of undershoot due to the neighboring vowels than does English bilabial consonant. This is probably due to the stricter demand on maintaining the consonantal contrasts, plain vs. palatalized, existing only in Russian.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.65 no.3
• /
• pp.183-187
• /
• 2016

Recently, power demand has been increasing every year according to variation of electrical equipments and temperature rise in summer season. So, much more overhead line is being demanded to copy with increasing power demand and operate reliable power system. This paper analysis the characteristics of long span overhead transmission line using special high-tension wire in such as a safety factor, coefficient of elasticity, and the coefficient of linear expansion. Based on the analysis, we proposed the effectiveness of special high-tension wire having much more advantages with respect to height of steel tower and dip compared with conventional ACSR in long span overhead transmission line.

• 한국가스학회:학술대회논문집
• /
• 1997.09a
• /
• pp.33-38
• /
• 1997

Demand of the clean and convenient natural gas has continuously increased with recognizing of the environment problem since liquefied natural gas was introduced in Korea. Clean fuel natural gas was supplied to each city through high tensile strength pipeline connected by welding. Grades of pipeline were divided into the high and middle pressure according to supply pressure. Pipeline was welded mainly SMA welding process due to its easy handling, the other welding process was adopted according to the constructing condition. We were examined on the microstructure variation and mechanical properties of weld metal for high pressure pipeline, API 5L X-42.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.66 no.4
• /
• pp.267-273
• /
• 2017

In recent years, there is an increasing demand for DC microgrid because the digital load due to DC increases and the efficiency of the distribution system increases due to loss of conversion losses and conversion stages due to reactive power compared to AC distribution. Currently, with the support of the KEPRI, the development of an electronic large-capacity circuit breaker for DC distribution protection, which has been underway since 2016, is proceeding. In this paper, as a part of this project, we modeled the DC microgrid connected with PV using PSCAD. The converter station, AC/DC converter control, PV and MPPT controller are designed. In order to evaluate the performance of the modeled DC microgrid, it is examined whether the voltage is adjusted according to the load variation.

• Journal of the Korea Furniture Society
• /
• v.28 no.1
• /
• pp.36-46
• /
• 2017

Recently, the demand for marine leisure industry is rapidly increasing due to the five-day work week and the per capita income approaching US $ 30,000. In particular, the Republic of Korea is surrounded by the sea on three sides and is composed of 3,150 islands and coastline. As shipbuilding infrastructure is abundant and the government is expected to actively support policies as a new growth engine, leisure boat furniture industry is expected to grow rapidly along with leisure boat manufacturing. Therefore, in this paper, after understanding the leisure boat (yacht) and analyzing the requirements of yacht furniture, we proposed a beautiful yacht furniture design that is lightweight, durable and safe using a 120-foot super yacht that can best show the characteristics of yacht furniture using wood bending technology and color variation of woods.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.28 no.1
• /
• pp.27-38
• /
• 1992

The paper presents a digital speed control approach of induction motor systems by using a digital redesign method and adopting a well known 2nd order model as the system model equation. The basic concept using the modeling equation is induced from the control theory stand point such that we can describe usually the motor system connected by inverter, generator and load etc. just as a mechanical system to be controlled. The concept does not demand us the complicated vector-based modeling equation adopted in the traditional methods for the speed control of induction motor. The effectiveness of the servo control system composed by the above mentioned design concept is illustrated by the experimental results in the presence of step reference change and generator load variation. It is observed from the experimental results that the steady state error of the experimental set up becomes zero after some regulation time and the induction motor system is robust in spite of reference signal change and load variation of generator.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.429-433
• /
• 2000

Recently the demand of motor for industrial household machinery is increasing. As Switching devices and control technology are progressing so the use of BLDC Motor is increasing But 3-Phase BLDC Motor generally used has pulsating torque and speed variation in commutation so the range of it's application is limited high speed application Especially to solve these problems it is necessary to increase phase to Motor so study of Poly-Phase BLDC Motor is progressing. In this paper we designed 7-Phase BLDC Motor drive system and MSTC(Minimum Switching Time Controller)

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.17 no.32
• /
• pp.199-207
• /
• 1994

A market has evolved from saturated state to over- saturated state because of variation of industrial circumstances. To improve the competitive power of a business under over- saturated state that the supply exceeds the demand, a business will seek after value management than quality management(QM). This paper define newly the concepts of value and quality and presents the value-management system based on it.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.507-512
• /
• 2000

Due to increasing demand toward improving product quality, various methodologies have been introduced. A brush type grinding tool is one of the most frequently used one to facilitate required process. In order to produce consistent burr shape, various machining conditions have been combined applied to disk grinding process. It has been observed that the burr dimension(shape and width) depends on the inclination angle between grinding disk and workpiece. Drastic increase of tool Wear has been also observed along the inclination angle variation. Various burr shapes have been captured and analyzed using image processing technique.

• Fisheries and Aquatic Sciences
• /
• v.2 no.2
• /
• pp.210-217
• /
• 1999

Chemical oxygen demand (COD), phytoplankton cell number and chlorophyll-a concentration (Chl-a), sediment mean grain size and ignition loss were studied to determine their temporal trends in the study area. Historical data of COD, cell number and Chl-a were gathered from the late 1960s or early 1980s to 1997, and trends in temporal domain were obtained from a simple regression. Sediments for grain size and ignition loss (as organic contents in sediments) were sampled from the Chokchon macrotidal flat bimonthly from September 1990 to November 1996, and were analyzed using the decomposition method of time series analysis. In general, the first three data showed increasing trends based on regression analysis. The trends of sediment grain size fluctuated in a neutral pathway while those of ignition loss yielded no increasing pattern. In contrast with the suggestions from Ahn and Choi (1998) who reported a coarsening variation in sediment grain size to be a cause of the directional and remarkable changes of macrofaunal communities in this area, we could not find such a corresponding variation pattern from our samples. In diagnosing eutrophication, a paradoxical phenomenon was encountered between the trends in water column (COD, cell number and Chl-a) and sediment (ignition loss) data. In this paper, we inferred the possible processes that produce the discrepancy. Some explanations and biological responses to eutrophication were predicted and discussed.