• Journal of Power Electronics
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• 제15권5호
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• pp.1295-1304
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• 2015

In this paper, an approach to extend the life of lead-acid batteries through the elimination of sulfation with "rest time" using the pulse current of a conventional DPV (Differential Pulse Voltammetry) method is discussed. A new rest time without "0" current in "saw-tooth" pattern pulses is proposed to overcome the "0" current (blackout period), which is a shortcoming of DPV. This will enable the proposed method to be used in the loaded state. In the proposed approach, ESSs (Energy Storage Systems) were discharged for 5 h twice per day for 6 months on weekdays. To observe the changes in the lifespan of the systems, for the same period, the changes in the impedances of lead-acid batteries which were being charged e without charging and discharging were measure and compared. This study is focused on determining the effectiveness of lead-acid batteries as ESSs.

• 대한산업공학회지
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• 제8권1호
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• pp.3-12
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• 1982

Three types of repair-ordering polices for the production facility with r-out-of-n configuration are considered. Policies are characterized by states of the system and two types of lead times ; regular lead time and expedited lead time. Optimum repair-ordering policy is determined by minimizing the cost rate for the system. Optimum policy consists of the type of policies and repair-ordering time. Variations of the optimum policies are observed with respect to variations of lead times and associated ordering costs and downtime cost, respectively.

• Journal of Korea Trade
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• 제27권1호
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• pp.101-118
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• 2023

Purpose - Korea became a trillion-dollar trading country in 2011. With the exponential increase in Korea's trade volume over the past decades, trade-related administrative burdens per capita for Korea Customs became enormous, for which the government established the Single Window, a trade-facilitating system, in 2004 to enhance the efficiency of customs-clearing procedures for traders. This paper focuses on finding whether the Korean Single Window system affects the country's trade facilitation positively through an empirical methodology. Design/methodology - To find empirical evidence that Single Window affects trade facilitation for the customs-clearing procedure, this study assumes that a time-efficient environment enables the handling of the increase in trade volume, under which four independent variables related to import customs-clearing procedures and two dependent variables to import were adopted for empirical analysis. The import customs procedures are classified into four steps from port entry to declaration acceptance. To understand the relationship between variables, scattered plots and correlation coefficients were calculated. Eight hypotheses were set and underwent simple linear regression. The data for analysis were collected by Korea Customs, and were about the lead time of import, the volume of imports in million USD, and the number of import declarations reported to customs offices on a monthly basis from 2005 to 2013. Findings - Six of the eight hypotheses showed the statistically significant result that lead time in the import customs-clearing procedure positively affects the number of import declaration reports and import volume. Specifically, Hypothesis 1, Hypothesis 2, and Hypothesis 3 strongly support the assumption lead time in import customs declaration has an inverse relationship with the number of import declarations, which means that the shorter the import lead time, the more import declaration increases. Research Limitations/Implications - With limited data accessibility to the government's custom-sclearing procedures, only the import lead time for customs clearance were adopted as independent variables. This paper, however, successfully found that the Single Window system contributed to trade facilitation. Originality/value - This study found that the time-saving Single Window system of Korea Customs enables itself to manage an exponentially-increasing trade volume by creating a trade-facilitating environment for customs personnel and traders, which may be a unique implication found through quantitative methodology.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권8호
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• pp.432-441
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• 2000

It is difficult to analyze the charging characteristics of the lead-acid battery, because of the influences by various non-linear and time-variant parameters. In this study, the charging characteristics of high capacity industrial lead-acid battery 630 Ah was investigated through experiments with respect to the variations of temperature and the aged state of battery during the charging process. The database of those characteristics is established from the results of experiments, and the fuzzy logic charging algorithm is suggested using them. The results of experiment shows that the industrial lead-acid batteries can be always fully charged within the saved charging time by the proposed charging control algorithm adapting to the variations of charging condition. This new charging concept will be useful for developing the advanced battery charger improving the efficiency of storing electricity.

• 대한안전경영과학회지
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• 제18권3호
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• pp.147-154
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• 2016

This paper suggests a specific model that could efficiently improve the interaction and the interface between MES(Manufacturing Execution System) server and PDA terminal through RFID(Radio Frequency Identification) system and bar-code system in automative transmission shipment place of the finished assembly parts. The proposed model shows that the new method by RF-Tag system can more efficiently perform to reduce processing time and loading time for shipment, compared with the current approach by bar-code system. It is noted in case of the method by RF-Tag that the effects of proposed model are as follows; (a) While the shipping lead time per truck for carrying by the current method was 35 minutes, the shipping lead time by the new method was 15 minutes. (b) While the accuracy for carrying by the current method was 50%, the accuracy by the new method was 99%.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.196-201
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• 2010

The influence of red lead($Pb_3O_4$) to curing and formation reaction properties when it was added in positive material of lead acid battery for vehicle use has been investigated. At the results, it was confirmed that the addition of red lead led 4BS crystal size to be smaller and increased the rates of 4BS formation and Pb consumption. Consequently the curing time was shortened to half compared with that of red lead-free one. In addition to this, the lead acid battery prepared by adding red lead showed 14% higher efficiency at the life cycle test than that without red lead.

• Toxicological Research
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• 제29권4호
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• pp.293-298
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• 2013

A method of detecting lead was developed using square wave anodic stripping voltammetry (SWASV) with DNA-carbon nanotube paste electrode (CNTPE). The results indicated a sensitive oxidation peak current of lead on the DNA-CNTPE. The curves were obtained within a concentration range of 50 $ngL^{-1}-20mgL^{-1}$ with preconcentration time of 100, 200, and 400 sec at the concentration of $mgL^{-1}$, ${\mu}gL^{-1}$, and $ngL^{-1}$, respectively. The observed relative standard deviation was 0.101% (n = 12) in the lead concentration of 30.0 ${\mu}gL^{-1}$ under optimum conditions. The low detection limit (S/N) was pegged at 8 $ngL^{-1}$ ($2.6{\times}10^{-8}M$). Results showed that the developed method can be used in real-time assay in vivo without requiring any pretreatment and pharmaceutical samples, and food samples, as well as other materials requiring water source contamination analyses.

• 대한산업공학회지
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• 제7권1호
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• pp.13-20
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• 1981

본 연구에서는 세가지 형태의 검사주문정책이 제시되었다. 부품 주문시 원래부품의 상태가 가동상태, 퇴화상태, 고장상태인가에 따라 보통주문, 특별주문, 긴급주문으로 분류되고, 각 주문형태는 각기 다른 인도기간으로 특정지워진다. 정책 I은 대체부품이 도착되면 원래부품이 가동중이라도 대체시키는 경우이고 정책 II는 도착된 대체부품을 원래부품의 고장발생때까지 재고시켜 두는 것이다. 정책 III은 대체부품이 도착되면 가동중인 원래부품에 검사를 한번 더 시행하여, 이것이 가동상태에 있으면 퇴화가 발생되는 평균시간까지 더 사용하고 난뒤 대체시키고, 퇴화상태에 있으면 대체부품과 즉시 대체시키는 것이다. 이와 같은 세가지 정책하에서 비용유효성 함수가 제시되고, 퇴화밀도함수와 고장밀도함수가 각각 Weibull과 지수분포를 따르는 경우 적정검사주문 시간을 구하고, 고장비용에 대한 부품가격과 고장비용에 대한 검사 비용의 변화에 따른 정책 변화가 분석되었다.

• 한국산업보건학회지
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• 제15권2호
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• pp.144-152
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• 2005

To evaluate the effect of lead biomarkers including bone lead on neurobehavioral test in lead workers, 652 lead workers without any occupational exposure to organic solvent, mercury and arsenic were agreed to participate this study. For the control subjects 102 non-occupationally lead exposed blue collar workers in general manufacturing industries were also joined this study. All study subjects joined this study with written informed consent. The study variables of lead exposure were blood and patella lead. For the general characteristics of study subjects, standardized questionnaire regarding age, sex, past disease history, job duration, body mass index (BMI), drinking and smoking habit were provided. For the past history of neurotoxicity related diseases, all study subjects were interviewed by qualified occupational health physician. The results obtained were as follows: 1. Compared with controls without occupational lead exposure, lead exposed subjects had worse performance on all tests(p<0.05). 2. After adjustment for covariates (age, sex, job duration, education level, BMI, smoking and drinking status), the signs of the regression coefficients for blood lead were negative for 13 of the 14 tests. Blood lead was a significant predictor of poorer scores on 8 tests (simple reaction time(ms & root MSD), Trail-Making Test B, Digit Symbol Substitution, Purdue Pegboard assembly, Digit Span Test, Benton Visual Retention, and Purdue pegboard both hand). 3. After adjustment for covariates (age, sex, job duration, education level, BMI, smoking and drinking status), the signs of the regression coefficients for patella lead were negative for 12 of the 14 tests. Patella lead was a significant predictor of poorer scores on 8 tests (simple reaction time(ms). Purdue Pegboard assembly, Digit Span Test, Benton Visual Retention. Pursuit Aiming rest (no. of correct & no. of incorrect), Purdue pegboard non-dominant hand and both hand). With above results, blood lead and patella lead were associated with poorer performance of neurobehavioral tests. In addition, patella lead was confirmed to be better predictor of manual dexterity test in neurobehavioral test battery in lead workers

• 한국환경보건학회지
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• 제27권1호
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• pp.83-87
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• 2001

In this study, the characteristics of lead removal by PVA and alginate bead which used widely as immobilizing agents were investigated, and the difference of removal amounts between pure PVA/alginate bead and Sargassum thunbergii immobilized bead was studied. All PVA beads, pure and S. thunbergii immobilized, reached an equilibrium state in about 1 hour, and S. thunbergii immobilized bead adsorbed more lead than pure one. But in the case of alginate beads, they needed much time, about 5 hours, to reach an equilibrium state, and adsorbed lead four times higher than PVA beads. Therefore, it was considered that alginate beads had more mass transfer resistance and function groups which adsorb lead such as hydroxyl, carboxyl and etc. than PVA bead. To examine the continuous usage of alginate beads, the process of adsorption/desorption of lead was conducted repeatedly. As the process proceeded, the amounts of lead adsorption decrease, so it was indicated that the non-desorbed lead from alginate bead at first adsorption/desorption process remained constantly.