• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.5
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• pp.436-442
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• 2020

ESS(energy storage system) has recently become an important power source in various areas due to increased renewable energy resources. The more ESS is used, the less the effective capacity of the ESS. Therefore, it is important to manage the remaining useful lifetime(RUL). RUL can be checked regularly by inspectors, but it is common to be monitored and estimated by an automated monitoring system. The accurate state estimation is important to ESS operator for economical and efficient operation. RUL estimation model usually requires complex mathematical calculations consisting of cycle aging and calendar aging that are caused by the operation frequency and over time, respectively. A lightweight RUL estimation model is required to be embedded in low-performance processors that are installed on ESS. In this paper, a lightweight ESS RUL estimation model is proposed to operate on low-performance micro-processors. The simulation results show less than 1% errors compared to the original RUL model case. In addition, a performance analysis is conducted based on ATmega 328. The results show 76.8 to 78.3 % of computational time reduction.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.21-31
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• 2010

This paper presents a design of PLL and SSCG for reducing the EMI effect at the electronic machinery and tools for DisplayPort application. This system is composed of the essential element of PLL and Charge-Pump2 and Reference Clock Divider to implement the SSCG operation. In this paper, 270MHz/162MHz dual-mode PLL that can provide 10-phase and 1.35GHz/810MHz PLL that can reduce the jitter are designed for 2.7Gbps/162Gbps DisplayPort application. The jitter can be reduced drastically by combining 270MHz/162MHz PLL with 2-stage 5 to 1 serializer and 1.35GHz PLL with 2 to 1 serializer. This paper propose the frequency divider topology which can share the divider between modes and guarantee the 50% duty ratio. And, the output current mismatch can be reduced by using the proposed charge-pump topology. It is implemented using 0.13 um CMOS process and die areas of 270MHz/162MHz PLL and 1.35GHz/810MHz PLL are $650um\;{\times}\;500um$ and $600um\;{\times}\;500um$, respectively. The VCO tuning range of 270 MHz/162 MHz PLL is 330 MHz and the phase noise is -114 dBc/Hz at 1 MHz offset. The measured SSCG down spread amplitude is 0.5% and modulation frequency is 31kHz. The total power consumption is 48mW.

• Korea and Global Affairs
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• v.1 no.2
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• pp.171-208
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• 2017

This paper is to analyze the type characteristics and prospects of the North Korean nuclear strategy. To this end, the paper is composed of 5 chapters titled introduction; the concept and type of nuclear strategy; the nuclear capabilities of North Korea and the declarative nuclear strategy; the operational characteristics and prospects of the North Korean nuclear strategy; and conclusion. Recently, the deployment of nuclear weapons and the enhancement of nuclear capabilities in North Korea have raised serious problems in our security and military preparedness. Nuclear strategy means military strategy related to the organization, deployment and operation of nuclear weapons. The study of North Korea's nuclear strategy begins with a very realistic assumption that the nuclear arsenal of North Korea has been substantiated. It is a measure based on North Korea's nuclear arsenal that our defense authorities present the concepts of preemptive attack, missile defense, and mass retaliation as countermeasures against the North Korean nuclear issue and are in the process of introducing and deploying them. The declared nuclear declaration strategy of the DPRK is summarized as: (1)Nuclear deterrence and retaliation strategy under the (North Korea's) Nuclear Weapons Act, (2)Nuclear preemptive aggression, (3)The principle of 'no first use' of nuclear weapons in the 7th Congress. And the intentions and operational characteristics of the North Korean nuclear strategy are as follows: (1)Avoiding blame through imitation of existing nuclear state practices, (2)Favoring of nuclear strategy through declarative nuclear strategy, (3)Non-settlement of nuclear strategy due to gap between nuclear capability and nuclear posture. North Korea has declared itself a nuclear-weapon state through the revised Constitution(2012.7), the Line of 'Construction of the Nuclear Armed Forces and the Economy'(2013.3), and the Nuclear Weapons Act(2013.4). However, the status of "nuclear nations" can only be granted by the NPT, which is already a closed system. Realistically, a robust ROK-US alliance and close US-ROK cooperation are crucial to curbing and overcoming the North Korean nuclear threat we face. On this basis, it is essential not only to deter North Korea's nuclear attacks, but also to establish and implement our own short-term, middle-term and long-term political and military countermeasures for North Korea's denuclearization and disarmament.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.459-467
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• 2016

Due to the limited areal space for installation, borehole heat exchangers (BHEs) at depths deeper than 300 m are considered for geothermal heating and cooling in the urban area. The deep vertical closed-loop BHEs are unconventional due to the depth and the range of the typical installation depth is between 100 and 200 m in Korea. The BHE in the study consists of 50A (outer diameter 50 mm, SDR 11) PE U-tube pipe in a 150 mm diameter borehole with the depth of 300 m. In order to compensate the buoyancy caused by the low density of PE pipe ($0.94{\sim}0.96g/cm^3$) in the borehole filled with ground water, 10 weight band sets (4.6 kg/set) were attached to the bottom of U-tube. A thermal response test (TRT) and fundamental basic surveys on the thermophysical characteristics of the ground were conducted. Ground temperature measures around $15^{\circ}C$ from the surface to 100 m, and the geothermal gradient represents $1.9^{\circ}C/100m$ below 100 m. The TRT was conducted for 48 hours with 17.5 kW heat injection, 28.65 l/min at a circulation fluid flow rate indicates an average temperature difference $8.9^{\circ}C$ between inlet and outlet circulation fluid. The estimated thermophysical parameters are 3.0 W/mk of ground thermal conductivity and 0.104 mk/W of borehole thermal resistance. In the stepwise evaluation of TRT, the ground thermal conductivity was calculated at the standard deviation of 0.16 after the initial 13 hours. The sensitivity analysis on the borehole thermal resistance was also conducted with respect to the PE pipe diameter and the thermal conductivity of backfill material. The borehole thermal resistivity slightly decreased with the increase of the two parameters.