• Bulletin of the Korean Chemical Society
• /
• v.8 no.3
• /
• pp.168-170
• /
• 1987

The reaction between 1-benzyl-3-carbamoyl-1,4-dihydropyridine (BNAH) 1 and various 1-arylpyridinium salts 2, and the reaction between 1-(4-methylphenyl)-1,4-dihydropyridine 4b and 1-aryl-3-carbamoylpyridinium (1-arylnicotinamide) salts 5 were carried out. The extents of reaction in equilibrium were estimated by nmr integration data. The equilibrium constants for the reactions, K, and the standard Gibbs free energy changes for the reduction of the pyridinium salts to the corresponding 1,4-dihydropyridines ${\Delta}G^{\circ}'$ were evaluated. The Hammett plot of log K for the reaction between 1 and 2, and ${\Delta}G^{\circ}'$ against ${\sigma}_p$ of the substituents in 1-aryl moiety shows linear correlation with the reaction constant ${\rho}$ of 9.4 (for log K vs ${\sigma}_p$) and -54.5 KJ/mole (for ${\Delta}G^{\circ}'$ vs ${\sigma}_p$). It was found that 1-aryl-1,4-dihydropyridines have much higher reducing power than the corresponding 1-aryl-1,4-dihydronicotinamides, and the power is affected greatly by the electron-withdrawing ability of the substituents in aryl group. The reactions were utilized for preparation of 1,4-dihydropyridines bearing highly electron-withdrawing groups such as 4-nitrophenyl and 2,4-dinitrophenyl, which could not be obtained by conventional dithionite reduction of the corresponding pyridinium salts due to the base-labile nature of the salts.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.79.3-80
• /
• 2017

Molecular clouds are the sites of stellar birth. Turbulence is a natural phenomenon in molecular clouds, which largely determines the density and velocity fields. Additionally turbulent energy dissipation can affect the gas kinetic temperature via shocks. Turbulence thus controls the mode and tempo of star formation. However, despite its important role in star formation, the properties of turbulence remain poorly understood. As part of the Taeduk Radio Astronomy Observatory (TRAO) Key Science Program (KSP), "Mapping turbulent properties of star-forming molecular clouds down to the sonic scale (PI: Jeong-Eun Lee)", we have been mapping two star-forming clouds, the Orion A and the ${\rho}$ Ophiuchus molecular clouds in 3 sets of lines (13CO 1-0/C18O 1-0, HCN 1-0/HCO+ 1-0, and CS 2-1/N2H+ 1-0) using the TRAO 14-m telescope. We apply a Principal Component Analysis (PCA), which is an useful tool to represent turbulent power spectrum. We will present the preliminary results of our TRAO KSP toward two regions: OMC 1-4 in the Orion A cloud, and L1688 in the ${\rho}$ Ophiuchus cloud.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.7
• /
• pp.824-832
• /
• 2018

According to the government's policy to demonstrate and expand the renewable energy sources, distributed generators such as PV and WP are installed and operated in distribution systems. However, there are many issues related to power quality problems including over voltage and under voltage of customers. In order to overcome these problems, the electric power company have installed a step voltage regulator (SVR) in primary feeders interconnected with distributed generators, and also have established the technical guidelines for the distributed generators to stabilize the customer voltages in distribution systems. However, it is difficult to maintain the customer voltages within allowable limit. Therefore, this paper reviews the problems of voltage control by SVR in a distribution systems interconnected with a large amount of PV systems, and proposes characteristics of operating range and voltage control limit of the small hydropower generators. Also, with the estimation of the influence to the power system voltages from the voltage control mode of generators, this paper proposes the optimal voltage control algorithm of the small hydropower generators. By programming the proposed algorithm into control simulator of exciter, it is confirmed that the proposed algorithm can contribute the voltage stabilization in distribution systems interconnected with large scaled PV systems.

• Proceedings of the KAIS Fall Conference
• /
• 2012.05b
• /
• pp.512-516
• /
• 2012

Recently the Korean government's green energy growth policy has been taken at the national level due to the sufficient supply of renewable energy. Some specific technique should be taken in consideration for the operation of the grid voltage and power quality management. In this case, there may have some chance of operational problems. Typical problems arise when grid-connected solar power produced by Pacific sunshine. The power flow in the reverse direction can create overvoltage on the distribution line and gives value of malfunction on the system. Line voltage and overvoltage adjustment practice can stop these symptoms occurred. Under these circumstances, this paper presents an interconnection test devices for photovoltaic(PV) systems composed of distribution system simulator, PV system simulator and control and monitoring systems using the LabVIEW S/W, and simulates the customer voltage characteristics considering the 3 parameters on the introduction capacity for PV systems, system configuration and Power factor. This paper also proposes a new calculation algorithm for voltage profile to make comparison between calculation values and test device values. The results show that the simulation results for the normal operation characteristics of PV systems which are very practical and effective.

• Journal of Korean Physical Therapy Science
• /
• v.7 no.2
• /
• pp.559-565
• /
• 2000

This studies were to investigate the effects of low power Helium-Neon Infra-Red (He-Ne IR) laser on the healing of the peripheral neuropathy in diabetic rats. The twenty one Spraque-Dewley adult male rats were assigned to the 3 groups: the control group (7), the diabetic group (7) and the laser group (7). The diabetic group was induced with a single intravenous injection of 50mg/kg body weight streptozotocin dissolved to 0.01mol/L citrate buffer, pH 4.5. The experimental laser group was irradiated low power He-Ne IR laser for 5 minutes every day during 21 days to the diabetic group. The results were as follows: For on and two weeks with laser treatment, there were significantly increased the terminal latencies of the laser treatment group than those of diabetic group, but that was significantly decreased to be similar to the control group on the laser treatment group for three weeks. The change of the amplitude on the laser treatment groups for three weeks was significantly increased to be similar to normal group than that of the diabetic group. As the result, we thank that there were activately effected of lower power He-Ne IR laser on the heeling of the peripheral neurophathy in diabetic rats.

• The Journal of Korean Physical Therapy
• /
• v.12 no.2
• /
• pp.1-6
• /
• 2000

This studies were to investigate the effects of low power wavelengths Helium-Neon Infra-Red(He-Ne 1R) laser on the changes of the serum mineral components in burn rats. The thirty Spraque-Dawley adult male rats were assigned to the 5 groups: the experimental groups(3), the bum control group (1) and the control group(1). There was made three degree bum by the 250mW IR on the back of each rats. from 3 days after being burned. the experimental laser groups were irradiated low power wavelengths(292 Hz. 1168Hz, 4672Hz) He-He IR laser far 5 minutes every day during the 7 days. The results were as tallows: 1. There were significantly not changes of the levels of serum sodium between all experimental groups. 2. The concentration of potassium in serum on the treated with 292Hz wavelengths group during 5 minutes were significantly increased ,but with 1168Hz wavelenghths group were decreased to the those of burn group. 3. The concentrations of serum calcium in serum 1168Hz wavelengths laser group on the treated with 5 minutes laser were significantly higher to normal level than those of bum groups. As above results. the changes of the 2 essentials mineral(calcium and potassium) in serum levels on the healing process have meaningful effected with the low power wavelengths role on the treated with He-Ne IR laser.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1227-1234
• /
• 2011

Korea is a mountainous country, with as much as 70% of the area is covered by hills and mountains. This geography places constraints on the minimum radius of curvature for the rail network. It was expected that the speed of trains could be enhanced on the existing railway network without a huge investment in infrastructure by using tilting trains. The development of tilting trains in Korea started in 2001 as research & development project. A 6-car prototype test tilting train, called the Tilting Train eXpress (TTX), was built in December 2006 and experimental trials began in 2007. TTX has distributed power, is designed to run at 200 km/h, and has a planned service speed of 180 km/h. In this paper, we first describe the performance of tilting train, and then present the estimated running times, and the time saving compared with today's conventional trains and non-tilting trains, based on the Jungang line. So the time saving could be separated into two effects by higher track top-speed and tilting devices.

• Proceedings of the KIEE Conference
• /
• 1991.11a
• /
• pp.63-66
• /
• 1991

With the diversity of life patterns and the improvement of level in life which have been resulted from the economic development, people have showed the tendency to pursue the comfortable life as well as the home automation or intelligent house. Furthermore, the clean energy supply and management system have been introduced for the solution of environmental problem on earth and the effective utilization of energy. This study is to describe the battery energy storage device, which is one of the clean energy supply and management systems that are economically efficient in both sides of supply and demand. and able to solve the problem of energy crisis.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11a
• /
• pp.142-146
• /
• 2010

기존의 전압강하 해석방법은 4상한의 전압강하분만 고려하여 계산을 수행하여 분산전원의 연계에 따른 역조류의 영향을 전혀 고려할 수 없어서, 분산전원이 투입하게 되면 전압강하 크기인 스칼라에 방향만 반대로 표시함으로써 전압강하 계산에 큰 오차를 발생시킬 수 있는 문제점을 안고 있다. 따라서 본 논문에서는 분산전원의 투입에 따라 변하게 되는 역률(Cos${\theta}$)을 고려하여 분산전원 연계에 따른 역조류의 영향을 수학적인 삼각함수의 좌표평면 해석방법에 기반하여 분산전원의 출력량을 고려한 분산전원 대응형 전압강하계산 알고리즘을 제안하였다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.8
• /
• pp.1485-1491
• /
• 2011

This paper deals with the technical problems for the protection devices, by simulating test facilities of protection coordination for Photovoltaic systems. In order to analyze the operation characteristics for the protection devices in the case that the Photovoltaic systems with bi-directional power supply are located in the feeder, this paper proposes the test facilities composed of model distribution system, protection device and model Photovoltaic systems. By performing the simulation for operation characteristics for the protection devices based on the test facilities, this paper presents the malfunction mechanism for the protection devices. The test results show that this paper is practical and effective for the technical guideline for the Photovoltaic systems.