• 한국전기화학회:학술대회논문집
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• 1998.12a
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• pp.7-27
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• 1998

In order to design capacity of lithium ion battery, some calculations were carried out based on the characteristics of materials by the given battery shape and dimension. The principle of design was built by the interpretation of the correlation of material, electrochemical and battery factors. Parameters of materials are fundamental physical properties of constituent such as cathode. separator, anode, current collectors and electrolyte. Electrochemical factor includes potential pattern as a function of specific capacity, specific discharge capacity(or initial irreversible specific capacity or Ah efficiency) as a function of specific charge capacity and material balancing. Parameters of battery are dimension, construction hardware and performance. Battery capacity was simulated for a lithium cobalt dioxide as cathode and a hard carbon as anode to achieve 1100 mAh for the charge limit voltage of 4.2V, the weight ratio(+/-) of 2.4 and ICR18650. A fabricated test cell (ICR18650) which have weight ratio(+/-) of 2.4 discharged to 1093 mAh for the charge limit voltage of 4.2V. The sequential discharge capacity show good correspondence with designed capacity.

• Proceedings of the Safety Management and Science Conference
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• 2003.11a
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• pp.343-350
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• 2003

The best Ppy weight ratio was 7 wt% and the optimal electrode composition ratio was 78 : 17 : 5 wt.% of (MSP-20 : BP-20 =1 : 1), (Super P : Ppy =10 : 7) and P(VdF-co-HFP). Implantation of Ppy as the conducting agents have led to superior electrochemical characteristics because of the low of internal resistance and faradaic capacitance. The result of unit cell with Ppy 7 wt% were as follows: 28.02 Fig of specific capacitance, 1.34 Ω of DC-ESR and 0.36 Ω of AC-ESR. Unit cell showed a good stability up to 200 charge-discharge cycles, retaining 82% of their original capacity at 200 cycles. From the analysis of impedance, the electrodes with Ppy 7 wt% showed low ESR, low charge transfer resistance and quick reaction rate. It was inferred that quick charge-discharge was possible. As compared with the specific capacitance (rectangular shape) of CV, it was also concluded that the specific capacitance originated from thecompound phenomena of the faradaic capacitance by oxidation and reduction of Ppy and the non-faradaic capacitance by adsorption-desorption of activated carbon.

• Explosives and Blasting
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• v.23 no.1
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• pp.19-30
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• 2005

In this study, the standard particle velocity equations and the equation for calculating specific charge weight with application of rock fracture method using the finecker plus are suggested and the existing equation of fragmentation was transformed into one applicable to finecker plus. Standard rock fracture pattern was designed. Square root scaled equation is $V=345.39(D/\sqrt{W})^{-1.4484$. computable equation to specific charge wei인t is $W_f=(2.3\~2.5)\;f_agdV$, charge weight per hole is 0.54kg, and proportion of diameter 30cm fragmentation is about $48.7\%$. This rock fracture method nay him out to be more excellent than the other methods.

• Tunnel and Underground Space
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• v.11 no.3
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• pp.248-256
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• 2001

The cylindrical cut is most frequently used in tunnel blast regardless of their dimensions. In this study the new parallel cut is proposed to raise advance per round, which is considered to be an elevation of the traditional cylinder cuts. The general geometric pattern of a new cut with parallel blast holes is proposed. The detailed burden and spacing between the central blasthole and those of the four section are also given. The blast results between new cut and traditional cylinder cut are given. The main results of this study are as follows. 1) The average advances per rounds in new cuts can reach 99.5% of drilling length. That of traditional cylinder cuts are known approximately 90∼95% 2) Specific charge weight of new cut compare to that of cylinder cut is approximately reduced 5% from 1.363 to 1.297 kg/㎥ 3) Specific drilling rate is also reduced 8% from 2.393 to 2.130 m/㎥ 4) Vibrations, fly rock, and fragmentation produced by the new blast are to be proved superior to those of the traditional cylinder cuts.

• Explosives and Blasting
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• v.27 no.2
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• pp.33-41
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• 2009

Specific charge, also called powder factor, is defined as the total explosive mass in a blast divided with the total volume or weight of rock to be fragmented. It is a well-known fact that change in explosive consumption per ton or per cubic meter of rock is always a good indication of changed rock conditions. In mining, it is common to use explosive consumption per ton of ore as a measure of the blastability for rock. On the contrary, in civil engineering, it is common to use explosive consumption per cubic meter of rock. In this paper, we adopt the definition of the civil engineering because we are mainly concerned with tunnel blasting. Up to now, although various methods for tunnel blast design have been proposed, there are so many cases in which the proposed methods do not work well. These may be caused by the differences in rock conditions between countries or regions, and can give a serious technical difficulty to a contractor. But if we know the specific charge for a given rock, then the blast design can become much more easier. In this respect, we suggest an algorithm for tunnel blast design that can exactly produce the predetermined specific charge as a result of the design. The algorithm is based on the concept of assigning different fixation factors to various parts of tunnel section, and may be used in combination with the known methods of tunnel blast design.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.123-129
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• 1999

Initial electrochemical characteristics of $LiCoO_2$ electrode for lithium ion battery with various content of super s black as conductive material were evaluated through the charge/discharge with the potential range of 4.3V to 2.0V versus $Li^+/Li^+$. The rate of C/4 and C/2 by the 3 electrode test cell composed with an electrolytic solution of 1 mol/l $LiPF_6/EC+DEC(1:3\;by\; weight)$. Lithium was used as reference electrode. High impedance charge behavior was observed at early stage of charge. In the case of $3\%w/w$ of super s black as conductive material, the specific resistance of the high impedance releasing was $3.82\;{\Omega}\;{\cdot}\;g-LiCoCo_2$ at the current density of $0.5 mA/cm^2$, which corresponds 7 times of the specific resistance of electrode $(0.728 g-LiCoO_2)$. At second charge, the specific resistance of the high impedance releasing was 63 mn · g-Lico02, which corresponds 12eio of the specific resistance of electrode and only $1.7\%$ of that of the first charge. The first charge and discharge specific capacities at C/4 rate were 160-161 and $153\~155mAh/g-LiCoO_2$, respectively, to lead $95.4\~96.4\%$ of coulombic efficiencies and ca. $6 mAh/g-LiCoO_2$ of initial irreversible specific capacity. Specific resistance at the end of charge and rest showed low value at content of super s black between 2 and $7\%w/w$, which agreed with characteristics of irreversible specific capacity. Capacity densities were reduced by the increasing the content of conductive material. They were 447 and 431mAh/ml when 2 and $2.9\%w/w$ of super s black were used, respectively, at the rate of C/4.

• Journal of Power Electronics
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• v.11 no.2
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• pp.237-243
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• 2011

Lithium batteries are widely used in mobile electronic devices due to their higher voltage and energy density, lighter weight and longer life cycle when compared to other secondary batteries. In particular, a high demand for lithium batteries is expected for electric cars. In the case of the lithium batteries used in electric cars, driving distance must be calculated accurately and discharging should not be done below a level that makes it impossible to crank. Therefore, accurate information on the state-of-charge (SOC) becomes an essential element for reliable driving. In this paper, a novel method for estimating the SOC of lithium polymer batteries using AC impedance is proposed. In the proposed method, the parameters are extracted by fitting the measured impedance spectrum on an equivalent impedance model and the variation in the parameter values at each SOC is used to estimate the SOC. Also to shorten the long length of time required for the measurement of the impedance spectrum, a novel method is proposed that can extract the equivalent impedance model parameters of lithium polymer batteries with the impedance measured at only two specific frequencies. Experiments are conducted on lithium polymer batteries, with similar capacities, made by different manufacturers to prove the validity of the proposed method.

• Land and Housing Review
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• v.2 no.1
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• pp.35-46
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• 2011

This paper aims at examining the indices and their weights for the evaluation of local government to allocate reconstruction charge and reviewing the availability of them simulating local governments' evaluation. There has been no specific evaluation criteria existed, while central government has to allocate the reconstruction charge to local governments by the provision 3 of Restitution of Housing Reconstruction Gains Act. The results as follows : According to a survey on evaluation indices weight and AHP analysis, the weight of 'the housing welfare improve effort' is the highest with 25.1% among 5 upper-classification indices. Following this, each weight of 'housing welfare conditions(22.7%)', 'housing SOC establishment(22.5%)', 'the achievement and planning on reconstruction charge use(15.8%)', and 'housing sector achievement such as Bogeumjari(13.9%)' are ranked. Meanwhile, Among 16 lower-classification indices, 'the rate of minimum housing standard households(11.5%)', 'public rental housing supply(8.9%)', 'reconstruction charge use achievement(8.3%)', 'reconstruction charge use planning submit(7.5%)', and 'rate of water and sewage(6.3%)' hold high rank. The analysis results show the weight of 'housing sector achievement such as Bogeumjari' on the existing provisions should be decreased(30%${\rightarrow}$13.9%) as others' weight has to be slightly increased. According to the result of the simulation, Jeonbuk, Gyeongbuk, Jeonnam, Jeju, Gyeonggi received higher scores in the comprehensive evaluation, while Daejeon, Seoul, Incheon, Daegu and Gwangju, where the housing conditions are relatively good, received lower scores. These results of the analysis correspond with the direction of reconstruction charges allocation and indicate that the evaluation criteria used in this simulation is acceptable.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.819-828
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• 2022

Sensitivity of aircraft sizing depending on battery performance was studied for a generic quad tilt rotor type electric vertical takeoff and landing vehicle. The mission requirements proposed by Uber Elevate and NASA were used for initial sizing, and the calculated gross weight is ranged between 5,000lb and 11,000lb for battery specific energy range of 200-400Wh/kg in pack level and continuous discharge rate range of 4-5C. For the assumed gross weight of 7,000lb, the required battery performance was calculated with two different criteria: available power and energy, and the effects of battery specific energy and discharge rate are analyzed. The maximum discharge rate is also recommended considering failure cases such as one battery pack inoperative and one prop rotor inoperative.

• Korean Journal of Community Nutrition
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• v.7 no.1
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• pp.86-91
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• 2002

An analysis for a period of 15 months (from September 2000 to November 2001), of the nutrition counseling internet site, “Dietnet” served by the Korean Society of Community Nutrition, showed the following results. Nutrition counseling was conducted without charge by 50 professionals, including professors in the food and nutritional areas, medical doctors, and dietitians. Counselees consisted of mostly females under 30 years of age. Although two thirds of the users of this site asked questions anonymously, they were very sincere. They asked questions mostly related to their own concerns, but there were quite a few inquiries about their parents or grandparents. There were significant differences in the counseling contents depending on the ages of the counselees. Teenagers showed the highest interest in height growth and weight control, whereas people in their twenties were mostly interested in diseases, foods, and weight control. Those over the thirty made inquiries mostly about diseases. The most frequent questions were relevant to gastrointestinal, circulatory and hepatic diseases. As indicated above, counseling questions included of a variety of both comprehensive and specific questions. There were also quite a few questions related to decisions on the correct usage of specific foods. Therefore, we recommend that more professionals, such as food science majors, medical doctors who practice western and oriental medicine, and other professionals who specialize in psychological behaviors related to weight control and infant food habits be recruited to serve the site more effectively and intensively. In light of the further need for internet sites with nutrition counseling and delivery of nutritional information to the public, nutritionists capable of managing websites are also required.