• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.505-508
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• 2006

Self-leveling mortar is walkable bottom mortar which can maintain the horizontality of self fluid and have the the quick-setting quality, the low-human-effort practicable material of high-quality bottom in construction. In accordance with more adhesive strength with bottom side and absorption control, Primer is used for purpose to prevent pin-hole occurrence by self leveling mortar application prior to construction. This study is composed measurement of absorption, adhesive strength. Used material is NP-40 as nonionic emulsifying agent, uses SA-210L as negative ion emulsifying agent, uses APS, SBS as ridical initiator. A result of test, in accordance with image of Primer, as low temperature and application frequency, indicates low absorption rate and adhesive strength, as solid powder and dryness time is increse, absorption rate and adhesive strength lowly shows figure.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.719-722
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• 2002

기저부하조성 및 부하율 향상을 위한 심야전력요금제도의 정착으로 최근 심야전력축열기기의 보급이 활성화되고 있다. 그러나 모든 심야전력축열기기들이 심야요금개시시간대인 2f시경에 동시에 가동됨에 따라 23시경에 심야전력 부하가 최대에 이르러 전력피크가 발생하여 한전의 수요관리에 큰 어려움을 주고 있다 따라서 이 피크 부하를 심야전력 공급시간대의 저 부하시간대로 분산시킬 수 있는 심야전력기기 공급시간을 제어하는 통전제어장치가 필요하게 되었으며, 이미 축열식전기보일러와 축열식전기온수기에는 개발 보급되고 있는 실정이다. 이 논문에서는 다른 심야전력축열기기와는 달리 자연방열의 바닥축열난방방식인 축열식전기온돌의 통전제어장치 알고리즘을 실증실험을 통해서 검증하였다.

• Solar Energy
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• v.19 no.4
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• pp.63-69
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• 1999

The conventional grid connected PV(Photovoltaic) system has a unstable output pattern due to its dependence on the weather condition, although solar-cell array averagely has a regular output characteristics to have a peak output nearly at noon. Therefore assuming the high density grid connection in the future, this unstable output pattern can be one of the main reasons to generate power disturbance such as voltage variation, frequency variation and harmonic voltage generation in low voltage distribution line. However general grid connected solar-cell system do not have functions to cope with these disturbances. Therefore this study proposed a advanced type grid connected PV system with functions to suppress output power fluctuation due to solar-cell array output variation and showed the levelling effect of fluctuation due to instantaneous array output variation.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.128-130
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• 2001

심야전력요금제도의 정착으로 최근 심야전력축열기기의 보급이 활성화되고 있다. 그러나 모든 심야 전력축열기기들이 심야요금개시시간대인 22:00경에 동시에 가동됨에 따라 23:00에 심야전력 부하가 최대에 이르러 전력피크가 발생하여 한전의 수요관리에 큰 어려움을 주고 있다. 따라서 이 피크 부하를 심야전력 공급시간대의 저부하시간대로 분산시킬 수 있는 심야 전력축열기기 통전시간제어가 필요하게 되었다.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.180-183
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• 2000

The Battery Energy Storage System(BESS) has lots of advantages such as load levelling, quick response emergency power(spinning reserve), frequency and voltage control, improvement of reliability, and deferred generation and transmission construction. The economic feasibility requires justification from the customer side of meter to promoting the dissemination of BESS nationally. In this paper, we proposed the economic assessment model of customer owned Battery Energy Storage System(BESS) which is complemented and improved the existing model. The proposed model is applied to the typical customer type(light-industrial commercial, and residential) which are taken from the statistical analysis on the load profile survey of Korea Electric Power COmpany (KEPCO). The economic assessment performed for each customer type to justifying their economic feasibility of BESS installation from the economic measures such as payback period, overall benefits, ROI, and ROR. The results of this paper are useful to the customer investment decision making and the national energy policy & strategy.

• Journal of Biosystems Engineering
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• v.15 no.1
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• pp.52-60
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• 1990

The main purpose of this report is to analyse the utilization results of farm machinery, farm mechanization rate and influences on the farm household economy. These results are summarized as follows : 1) The annual working days of major farm machinery are from 34.3 to 68.8 days for power tillers and tractors ; 7.9 to 8.5 days for rice transplanters ; 3.6 to 6.9 days for binders ; and, from 18.6 to 20.6 days for combines. Also income and expenditures of the farm management reveals al surplus in major farm machinery except for binders. 2) The popularization rate of major farm machinery is currently low, reaching the level of the early 1970's in Japan and the level of the early 1980's in Taiwan for rice transplanters and harvesters respectively. 3) The farm mechanization rate is 81.7% in plowing & levelling, 66.3% in rice transplanting, 87.5% in pest and disease control, 62.1% in harvesting and 12.5% in drying. However the farm mechanization rate of rice transplanting, harvesting and drying still remains at a low level. 4) The composition rates of farm machinery and implements are 10.2% in farm management expenditures (23.6% in Japan) and 13.2% in fixed capitals (29.4% in Japan) which still reflect a low level, and below that of the 1970's in Japan. From these analysis results, farm mechanization contributes to the improvement of farm management. Nevertheless, the popularization status and mechanization rate are still at a low level in korea. Therefore, it is deemed desirable to furthure promote effective utilization methods and guide farmers in higher safety utilization and management technology.

• Journal of Sericultural and Entomological Science
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• v.37 no.2
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• pp.154-160
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• 1995

Dyeing behavior of Silk/Cationic dyeable polyester(CDP) mixed filament was investigated by using a cationic dye. The effect of pH, temperature and additives such as carrier, levelling agent and salt were examined for each silk and CDP component of mixed filament in order to find out the optimum dyeing condition. Based on these results, the dyeing behavior was investigated for Silk/CDP mixed filaments concering various dyeing parameters. The dye adsorption was significantly changed on the dyeing temperature, carrier addition and pH of the dyebath. Specially, the dye migration phynomena were observed for a mixed filament, showing that the dyes initially observed on the surface of silk fiber migrate to the CDP component during a dyeing process. The dyeing of Silk/CDP mixed filaments accompanied by dye migration and as a result, dye adsorption can be developed only for a CDP component. Therefore, the control of dyeing temperature is most important for a Silk/CDP mixed filament, in order that both silk and CDP component are able to be dyed by a cationic dye simultaneously in one bath/one dye system.

• Journal of the Korean Electrochemical Society
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• v.4 no.3
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• pp.132-137
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• 2001

Recently, the demand for notebook PC with lithium ion batteries has steadily increased and consumers require them to adopt a SBP(smart battery pack) able to predict the remaining capacity and the run time of batteries precisely. The SBP is composed of a protection If, by which safety of lithium ion batteries is maintained against overcharge, overdischarge and overcurrent, and a smart IC, which calculates the remaining capacity and the remaining run time. The protection IC shut abmormal current down by using overcharge/overdischarge FET. A SBS(smart battery system) is composed of a system host, a smart battery and a smart battery charger. The smart ICs for SBP will be required to provide a low cost, low current consumption and small size. There will need to develop a microcomputer control type IC and an optimum algorism which is able to predict the residual capacity and the residual run time precisely. SBS will apply to many kinds of industry fields such as an electric bicycle, an electric vehicle, a load levelling and a military.

• Journal of Preventive Medicine and Public Health
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• v.17 no.1
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• pp.251-257
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• 1984

Low birth weight baby, defined as the baby born with less than or equal to 2,500g of body weight by WHO has been a great concern in the fold of maternal and child health since the low birth weight is a major cause of high perinatal mortality. Any measure to prevent the low birth weight baby is most desirable not only for saving the life of a baby but also for levelling up the health of the whole society. The authors attempted to figure out how some known maternal risk factors are related to the low birth weight and to measure their strengh of associations in terms of relative risk using hospital birth records. For this study, hospital birth records of 66 low birth weight cases and sex-parity matched 198 normal controls were chosen from Kangnam St. Mary's Hospital, Catholic Medical Center, and the data were analyzed in regards to several maternal factors. The risk factors studied were mother's age, mother's ABO blood type, previous histories of abortion, low birth weight baby, fetal wastage, and maternal diseases represented by anemia, hypertension, proteinuria, and glucosuria. The results obtained in this study were as follows: 1. The mean body weight of the cases and controls were 1,955g and 3,251g, respectively, and the heights were 41cm for cases and 50cm for controls. Mean gestation periods of cases and controls were 34 weeks and 39 weeks, respectively. 2. Young mother(less than or equal to 20 years of age) or old mother(more than or equal to 30 years of age) experienced more frequently the delivery of low birth weight babies than mothers in between 21 and 29 years of age. But the difference was not statistically significant. 3. Mothers whose blood type was O tended to have slighty higher frequency of low birth weight babies while B mothers have lower frequency. But the difference was not statistically significant too. 4. Those mothers who had experienced low birth weight baby in the past tended to give more births of low birth weight babies. This factor is even statistically significant and the relative risk of the prior experience of low birth weight was 6.7. 5. Mothers with experience of fetal losses and mothers of more than two pregnancies had higher frequency of low birth weight than the mothers with no fatal losses and of first pregnancy, but the difference was not statistically significant. 6. Statistically significant higher frequency of low birth weight were found in mothers with hypertension(odds ratio=4.07), anemia(odds ratio=22,33), and proteinuria(odds ratio=2.79). In summary, these study results strongly suggest that in order to prevent the low birth weight, special care should be made when the mother is too young or too old, and when the mother has experienced deliveries of low birth weight and fetal deaths. Medical control for the maternal diseases such as anemia and hypertension is also needed before or during the pregnency.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.2
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• pp.78-90
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• 2021

In order to construct a precision geoid, it has been diversified into land, sea, aviation, and satellite gravity measurement methods, and measurement technology has developed, making it possible to secure high-resolution, high-precision gravity data. The construction of precision geoids can be fast and conveniently decided through GNSS surveys without separate leveling, and since 2014, the National Geographic Information Institute has been developing a hybrid geoid model to improve the accuracy of height surveying based on GNSS. In this study, the results of the GNSS height measurement were compared and analyzed choosing existing public reference points to verify the GNSS height measurement of public surveys. Experiments are conducted with GNSS height measurements and analyzed precision for public reference points on coastal, border, and mountainous terrain presented as low-precision areas or expected-to-be low-precision in research reports. To verify the GNSS height measurement, the GNSS ellipsoid height of the surrounding integrated datum to be used as a base point for the GNSS height measurement at the public datum. Based on the checked integrated datum, the GNSS ellipsoid of the public datum was calculated, and the elevation was calculated using the KNGeoid18 model and compared with the results of the direct level measurement elevation. The analysis showed that the results of GNSS height measurement at public reference points in the coastal, border, and mountainous areas were satisfied with the accuracy of public level measurement in grades 3 and 4. Through this study, GNSS level measurement can be used more efficiently than existing direct level measurements depending on the height accuracy required by users, and KNGeoids 18 can also be used in various fields such as autonomous vehicles and unmanned aerial vehicles.