• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.52-56
• /
• 2001

Experiments of 2 type on insulating compounds accomplished to change PVC using in URD(Underground) power cable jacketing. one was DB(Dielectric Breakdown) test on the pure base resins and the others were WVT(Water Vapor Transmission) test on the compounds which contained C/B(Carbon Black), anti-oxidant to base resin. a kind of specimens made by pressing to resin of pellet or lump form was HDPE(High Density Polyethylene), MDPE(Medium Density Polyehylene), LDPE(Low Density Polyethylene), LLDPE(Linear Low Density Polyethylene), PVC(Polyvinyl Chloride). As a results of AC DB and WVT test, we saw that strength of Insulation was HDPE> LLDPE = MDP E> LDPE and WVT ratio was HDPE

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

• KIEE International Transactions on Electrophysics and Applications
• /
• v.4C no.3
• /
• pp.101-105
• /
• 2004

The efficient power MOSFET inverter applied for a simple and low cost power supply is proposed for driving the dielectric barrier discharge (DBD) lamp load. For decades, the DBD phenomenon has been used for ozone gas production in industry. In this research, the ultraviolet and visible light sources utilizing the DBD lamp is considered as the load for solid-state high frequency power supply. It is found that the simple voltage-source single-ended quasi-resonant ZVS inverter with only one active power switch could effectively drive this load with the output power up to 700 W. The pulse density modulation based control scheme for the single-ended quasi-resonant ZVS inverter using a low voltage and high current power MOSFET switching device is proposed to provide a linear power regulation characteristic in the wide range 0-100％ of the full power as compared with the conventional control based Royer type parallel resonant inverter type power supplies.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.21 no.5
• /
• pp.381-387
• /
• 2016

Many efforts have focused on the improvement of power density and efficiency by downsizing the motor and inverter. Recently, Toyota, Honda, and GM realized that the compact-sized motor uses the hairpin structure with increased space factor. Reducing the maximum torque from high-speed technique also makes it possible to design the high-power density model. Toyota and Honda used the newly developed power semiconductor IGBT to decrease conduction loss for high-efficiency inverter. In particular, Toyota used the boost converter to increase the DC link voltage for high efficiency in low-torque high-speed region. Toyota and GM also used the double-sided cooling structure for miniaturization of inverter for high-power density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.143-146
• /
• 1994

In older to investigate the properties of electric conduction in low density polyethylene(LDPE) for power cable, the thickness of specimen was the 30, 100($\mu\textrm{m}$) of LDPE. The experimental condition for conductive properties was measured until the breakdown occurs at temperature ranges from 30 to 110[$^{\circ}C$] and in the electric field of 1 to 5 ${\times}$10$^2$[Mv/m]. As for increase of temperature, the current density of LDPE was increased with constant ratio in low field, but changes with exponential function in high field. The tunnel current of pre-breakdown region is shifted toward low field as much as thermal excitation energy.

• Proceedings of the IEEK Conference
• /
• 2000.11b
• /
• pp.91-94
• /
• 2000

This paper introduces the design of low-power, fast-locking delay locked-loop using complementary pass transistor logic(CPL). Low-power design has become one of the most important in the modem VLSI application. CPL has the advantage of fast speed, high density, and low power with signal buffering between stages. Based on this analysis, we concluded that the I/O performance can be beyond 500㎒, 2-poly, 2-metal 0.65$\mu\textrm{m}$, 3.3V supply.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.43 no.11 s.353
• /
• pp.98-104
• /
• 2006

The conventional burst-mode APC(Automatic Power Control) circuit had an effective structure that was suitable for a low power consumption and a monolithic chip. However, as data rate was increased, it caused errors due to the effect of the zero density. In this paper, we invented a new structured peak-comparator which could compensate the unbalance of the injected currents using double gated MOS and MOS diode. And we proposed a new burst-mode APC adopting it. The new peak-comparator in the proposed APC was very robust to zero density variations maintaining the correct decision point of the current comparison at high data rate. It was also suitable for a low power consumption and a monolithic chip due to lack of large capacitors.

• Journal of the Korean Society for Heat Treatment
• /
• v.8 no.3
• /
• pp.169-181
• /
• 1995

This study has been performed to investigate some effects of the power density and traverse speed of laser beam on the optical microstructure, hardness and fatigue resistance of gray cast iron treated by laser surface hardening technique. Optical micrograph has shown that the dissolution of graphite flakes and the coarsening of lath martensite tend to increase with a small amount of retained austenite as the power density increases under the condition of a given traverse speed. Hardness measurements have revealed that as the power density increases, hardness values of outermost surface layer increases from Hv=620 to Hv=647 in case of traverse speed of 2.0m/min at gray cast iron. Fatigue test has exhibited that the fatigue strength of laser surface hardened specimen is superier compared to that of untreated specimen, showing that values for the fatigue strength at $N_f=10^7$ of gray cast iron laser-surface-hardened at a low power density of $4076w/cm^2$ and a high power density of $8153w/cm^2$ under the condition of a given traverse speed of 2.0m/min are $15kg_f/mm^2$ and $20kg_f/mm^2$, respectively, whereas the fatigue strength of untreated specimen is $11kg_f/mm^2$. Under high stress-low cycle condition a noraml brittleness fracture appears, whereas a ductile fracture with beach mark is observed in the specimen tested under low stress-high cycle condition.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.5
• /
• pp.553-559
• /
• 2016

There has been increasing global interest in the environmental pollution problems produced by fossil fuel consumption and greenhouse gas emissions. In order to tackle these issues, new renewable energy such as solar, wind, bio gas, fuel cell and pressure retarded osmosis(PRO) have been developed extensively. Among these energy sources, PRO is one of the salinity gradient power generation methods. In PRO, energy is obtained by the osmotic pressure generated from the concentration difference between high and low concentration solutions separated by a semipermeable membrane. The development for high power density PRO membranes is imperative with the purpose of commercialization. This study investigates development of thin film composite PRO membrane and spiral wound module for high power density. Also, the influence of membrane backing layer on power density was identified, and the characteristic factors of PRO membranes was determined. Different backing layers were used to improve power density. As expected, the PRO membrane with more porous backing layer showed higher power density.

• Journal of information and communication convergence engineering
• /
• v.16 no.2
• /
• pp.84-92
• /
• 2018

For large wireless sensor networks running on battery power, the time synchronization of all sensor nodes is becoming a crucial task for waking up sensor nodes with exact timing and controlling transmission and reception timing. However, as network size increases, this synchronization process tends to require long processing time consume significant power. Furthermore, a naïve synchronization scheduler may leave some nodes unsynchronized. This paper proposes a power-efficient scheduling algorithm for time synchronization utilizing the notion of density, which is defined by the number of neighboring nodes within wireless range. The proposed scheduling algorithm elects a sequence of minimal reference nodes that can complete the synchronization with the smallest possible number of hops and lowest possible power consumption. Additionally, it ensures coverage of all sensor nodes utilizing a two-pass synchronization scheduling process. We implemented the proposed synchronization algorithm in a network simulator. Extensive simulation results demonstrate that the proposed algorithm can reduce the power consumption required for the periodic synchronization process by up to 40% for large sensor networks compared to a simplistic multi-hop synchronization method.