• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.398-404
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• 1999

The EGR is needed for one of various strategies to reduce NOx emission. But to get the proper EGR rate the intake and exhaust system become complicated. That is a reason why we consider using the built0in EGR system. The built-in EGR is a system which reduces Nox by controling the residual gas fraction in cylinder by changing valve timing and valve lift of intake and exhaust. In this paper characteristics of volumetric efficiency and residual gas fraction in cylinder were investigated for various engine speeds by changing valve timing and valve lift of intake and exhaust. In this paper characteristics of volumetric efficiency and residual gas fraction in cylinder were investigated for various engine speeds by changing valve timing and valve lift of intake and exhaust in the 4 stroke-cycle diesel engine. Volumetric efficiency and residual gas fraction were calculated by the method of characteristics. As the results the possibility of suing the built-in EGR system was confirmed.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.9-15
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• 1999

A digital CDI(Capacitive Discharge Ignition) system on small two stroke motorcycle engine was developed in this paper, This CDI system with microprocessor as its main part has more flexible spark timing than the conventional CDI system because of its programmable characteristics. The principle of this digital CDI system and the design methods of hardware and software were presented in this paper, Two stroke small engine was tested to investigate the performance of digital CDI system And also this system was investigated to optimize the engine performance. Also comparison between conventional CDI can provide better spark timing variation than the conventional system. The part and full load test results show that the engine power was increased about 10-20% and fuel consumption was decreased about 10-20% simultaneously. Furthermore, this digital CDI system has simple structure, low cost and very little modification are required. It is a promising technology to substitute for the widely used conventional CDI system.

• 음성과학
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• 제8권1호
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• pp.77-91
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• 2001

This paper investigates the timing of Korean spoken in a news-reading speech style in order to improve the naturalness of durations used in Korean speech synthesis. Each segment in a corpus of 671 read sentences was annotated with 69 segmental and prosodic features so that the measured duration could be correlated with the context in which it occurred. A CART model based on the features showed a correlation coefficient of 0.79 with an RMSE (root mean squared prediction error) of 23 ms between actual and predicted durations in reserved test data. These results are comparable with recent published results in Korean and similar to results found in other languages. An analysis of the classification tree shows that phrasal structure has the greatest effect on the segment duration, followed by syllable structure and the manner features of surrounding segments. The place features of surrounding segments only have small effects. The model has application in Korean speech synthesis systems.

• Journal of Positioning, Navigation, and Timing
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• 제8권1호
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• pp.1-12
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• 2019

In this paper, we implement a navigation software of a Global Navigation Satellite System (GNSS) receiver based on a commercial purpose GNSS software receiver platform and verify its performance by performing experimental tests for various GNSS signals available in Korea region. The SX3, employed in this paper, is composed of an application program and a Radio Frequency (RF) frontend, and can capture and process multi-constellation and multi-frequency GNSS signals. All the signal processing procedure of SX3 is accessible by the receiver software designer. In particular for an easy research and development, the Application Programing Interface (API) of the SX3 has a flexible architecture to upgrade or change the existing software program, equipped with a real-time monitoring function to monitor all the API executions. Users can easily apply and experiment with the developed algorithms using a form of Dynamic Link Library (DLL) files. Thus, by utilizing this flexible architecture, the cost and effort to develop a GNSS receiver can be greatly reduced.

• 한국생산제조학회지
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• 제8권2호
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• pp.94-94
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• 1999

Natural gas is considered to be on e of the most promising candidates for a clean substitute fuel and a great amount of research on the compressed natural gas(CNG) fueled vehicle has been performed. In this s tudy, we try to understand the property of CNG fuel with using CNG engine experiment. In order to present the direction and application of CNG, we experiment with various operating conditions that is, spark timing, A/F ratio, air quantity and fuel quantity, etc. 11,967 cc engine was used in the experiment and the engine fuel ratio was determined in the way that the performance of dedicated CNG engine is corresponded to that of existing diesel engine. The performance and dedicated CNG engine were measured by changing the fuel injection timing. The dedicated CNG engine was proved to be good in describing the experimental results and according to the actual road test, acceleration and constant speed driving for dedicated CNG engine was better than existing diesel engine.

• 한국지형학회지
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• 제26권4호
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• pp.21-31
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• 2019

Timing of terrace formation is a key information for understanding the evolution of fluvial systems. In particular, dating strath terrace (i.e. timing of terrace abandonment) is more difficult than depositional terrace that is conventionally constrained by radiocarbon, OSL and other dating methods targeting samples within terrace deposit. Surface exposure dating utilizing cosmogenic ¹⁰Be provides more reliability because it can be applied directly to the surface of a fluvial terrace. Thus, this method has been increasingly used for alluvial deposits. As well as other geomorphic surfaces over the last decades. Some inherent conditions, however, such as post-depositional ¹⁰Be concentration (i.e. inheritance), surface erosion rate, and density change challenge the application of cosmogenic ¹⁰Be to depositional terrace surface against simple bedrock surface. Here we present the first application of ¹⁰Be depth profile dating to a thin-gravel covered strath terrace in Korea. Monte Carlo simulation (MCS) helped us in better constraining the timing of abandonment of the strath terrace, since which its surface stochastically denuded with time, causing unexpected change of ¹⁰Be production with depth. The age of the strath terrace estimated by MCS was 109 ka, ~4% older than the one (104 ka) calculated by simple depth profile dating, which yielded the best-fit surface erosion rate of 2.1 mm/ka. Our study demonstrates that the application of ¹⁰Be depth profile dating of strath terrace using MCS is more robust and reliable because it considers post-depositional change of initial conditions such as erosion rate.

• 대한전자공학회논문지
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• 제24권4호
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• pp.652-657
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• 1987

This paper describes an application of CMOS Gate Array Integrated Cricuits to the implementation of three functional units: A Multiplexer, Time Switch, and Demultiplexer in the Switching Network and Digital Line Concentrator of TDX-1 system, which is a fully digital time division electronic switching system in Korea. The application of CMOS Gate Array Integrated Circuits significantly improves the overall system performance in terms of power consumption, cost, size, reliability, and timing margin, etc.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1472-1479
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• 2002

Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the emission characteristics of 4 stroke marine diesel engines in E3 cycle (propulsion application) and D2 cycle (generation application). Also the effects of important operating parameters in terms of intake air pressure and temperature, and maximum combustion pressure on the specific emissions are described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that NOx emission level in E3 cycle is higher than that in D2 cycle due to lower engine speed at low load and the maximum combustion pressure by fuel injection timing control and intake air temperature has strong influence on NOx emission production. And CO, HC emissions are not affected by maximum combustion pressure and intake air pressure and temperature.

• 한국잡초학회지
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• 제32권3호
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• pp.240-255
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• 2012

본 연구의 목적은 설포닐우레아계 제초제에 대한 저항성 잡초종 방제에 효과적인 HPPD(4-hydroxy phenylpyruvate dioxygenase) 저해 제초제, mestrione, benzobicyclone 및 tefuryltrion에 대한 벼 품종 간의 약해정도를 구명하기 위하여 수행하였다. 총 26 벼 품종(통일형 8품종 그리고 일본형 18품종)은 육묘상자에서 25일 동안 생육시킨 후 이앙하였고, 이앙 후 5, 10, 그리고 15일에 각각의 제초제를 표준량 그리고 배량을 처리하였다. 비록 mestrione, benzobicyclone 및 tefuryltrion 제초제가 동일한 HPPD 저해 제초제들이지만 이들 제초제의 처리 시기나 약량에 따라 벼 품종별 약해정도와 증상은 서로 상이하였다. 시험약제 모두에서 통일형 품종이 일본형 품종보다 약해가 심하게 발생하였다. Mesotrione은 약량이 증가할수록, benzobicyclon은 처리시기가 빠르고 약량이 증가할수록 약해가 심하였다. 반면에 tefuryltrion은 처리시기와 약량에 따라 품종간의 약해변이는 크지 않았다. Mesotrione과 benzobicyclon에 대한 통일형 품종인 한강찰벼 1호와 향미벼 1호, 초다수성 품종인 남천벼, 다산벼, 아름벼, 그리고 한아름벼 품종들의 약해는 처리시기 및 약량에 관계없이 백화, 잎과 줄기의 갈변, 잎 꺾임, 괴사를 동반한 5~8 정도의 약해 증상을 보인 반면에 tefuryltrion은 단지 1~3 정도의 황화 및 백화, 갈변 증상만을 보였다. 일본형 품종에 대한 약해는 제초제의 처리시 기와 약량에 따라 1~2 정도의 가벼운 약해 증상을 보였지만 제초제 종류에 따라 품종간에 유의적인 차이를 나타냈다. 13개의 일본형 품종들은 benzobicyclone에 대해 민감하였으며, 일본형 4품종과 7품종들은 각각의 mestrione과 tefuryltrion에 대해 황화 및 백화를 동반한 증상이 나타났다. 그러므로 mestrione과 benzobicyclone, 그리고 tefuryltrion 성분이 함유된 혼합제는 처리시기 및 처리약량에 관계없이 벼 생태형 간에 심각한 약해 증상을 나타내므로 식용(기능성용 및 가공용 벼) 또는 사료용을 위한 벼 재배 포장에서의 사용을 지양해야 할 것으로 사료된다.

• 농업과학연구
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• 제41권1호
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• pp.17-22
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• 2014

This study was conducted to evaluate the efficacy of formulations and application timings of imazosulfuron+fentrazamide in rice field. Weeding efficacy of imazosulfuron+fentrazamide SC (75+300 g a.i./ha) was more than 95% except Bidens tripartita. The efficacy of this formulation was not related to its formulations but was highly related to application timing. Herbicide application before 5 days after transplanting was best timing to get a maximum weed control. Systemic application before and after transplanting was much higher than single application for weed control. Second leaf stage of Echinochloa spp. and sulfonylurea resistant Monochoria vaginalis was controled over 90% in the imazosulfuron+fentrazamide SC (75+300 g a.i./ha). Based on these data, imazosulfuron+fentrazamide can be applied to provide effective weed control especially in the field infested with herbicide resistant M. vaginalis.