• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.79-85
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• 2002

본 연구는 대추 수확기개발을 위한 기초연구로써 대추의 열매, 잎, 잎줄기의 물리적 역학적 특성을 조사.분석하였으며, 그 결과를 요약하면 다음과 같다. .대추 열매의 평균 장경, 경, 부피, 무게, 탈과력은 각각 32.02 mm, 23.9 mm, 10.0$\times$$10^{-6}$m$^3$, 5.2~12.8g, 5.7 N으로 나타났다. .대추무게가 증가하면 탈과력은 증가하고, F/W는 감소하는 경향을 나타났다. .대추나무가지의 평균 탄성계수는 7.01$\times$$10^{8}$ N/m$^2$였고, 가지의 굵기가 증가하면서 감소하였다. .대추나무가지의 평균 비틀림 강성은 5.2$\times$$10^{7}$ N/m$^2$으로 나타났으며, 가지의 굵기가 증가하면서 음의 지수 함수적으로 감소하는 경향을 나타냈으나, 데이터가 일정한 범위에 산재해 있어 가지의 굵기에 따른 강성계수변화 특성은 일정한 경향으로는 나타나지 않았다. .대추 잎줄기의 평균 무게, 잎수, 길이가 각각 0.7g, 6.6개, 12.2 cm로 나타났다. .대추 잎의 평균 잎면적, 무게, 탈리력은 각각 13 $cm^2$, 0.2g, 4.4 N으로 나타났다. .종말속도는 대추 열매의 무게가 증가하면서 증가하고, 대추잎의 무게, 면적이 증가할수록 감소하는 경향을 나타냈으며, 잎줄기의 종말속도는 잎줄기 무게 혹은 잎줄기에 매달린 잎의 수와는 거의 영향을 받지 않는 것으로 나타났으며, 잎줄기의 길이가 증가할수록 약간씩 증가하는 경향을 나타냈다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.143-150
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• 2007

Using a panel data of Korea for $1979{\sim}2002$, this study investigates the determinants of the service sector employment share in Korea. In order to analyze the impact of macroeconomic factors on the service sector's employment share we estimate a simple panel model which is in line with Baumol's model. The panel GMM estimation results show that: 1) The increase in the share of service-related jobs in total employment tends to rise with GDP per capita, which confirms demand-bias hypothesis proposed by Clark. 2) We find that a crucial role in this process has been played by the productivity gap. As Baumol's hypothesis or Baumolis disease, the expansion of the employment share in services relative to industry is the direct consequence of services' lower productivity performances.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.3
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• pp.107-115
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• 2004

SHACAL-2 is a 256 bit block cipher with various key sizes based on the hash function SHA-2. Recently, it was recommended as one of the NESSIE selections. UP to now, no security flaws have been found in SHACAL-2. In this paper, we discuss the security of SHACAL-2 against an impossible differential attack. We propose two types of 14 round impossible characteristics and using them we attack 30 round SHACAL-2 with 512 bit 18y. This attack requires 744 chosen plaintexs and has time complexity of 2$^{495.1}$ 30 round SHACAL-2 encryptions.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.165-170
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• 2005

A basic study for the development of a disk type oil skimmer for a tank lorry, compares via experiments to the oil recovery differences by material between the existing oil skimmer disk and several discs which oil adhesion are possible. The experiment results in this study are summarized as follows: In all the disks, the mass of recovery of bunker-A oil was greater than light oil. In light oil, there was nearly no differences in the mass of oil recovery by disk material, but in the case of bunker A oil, recovery efficiency showed big differences depending on the disk materials. For light oil, the differences in the mass of oil recovery per unit of operation time from the initial time zone were hardly shown. However, the mass of recovery of bunker-A oil linearly increased from the initial operation time in all the disks and the increase shaped a slow moving trend as time went on; therefore, the mass of oil recovery per unit of operation time showed differences depending on time. This result shows that oil viscosity has an effect on the disk recovery efficiency. When comparing the mass of pure oil recovery and the mass of water recovery in the total mass of recovery by bunker-A oil, there was no difference in the mass of oil recovery between the window-aluminum material disk and the disks consisting of other materials, but the mass of water recovery of the former was relatively very small. This shows the most ideal result in view of oil recovery efficiency that considers the mass of water recovery. In conclusion, it was found that aluminum is the most advantageous as the material for tank lorry oil skimmer disk.

• Korean Journal of Agricultural Science
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• v.16 no.1
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• pp.118-128
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• 1989

This experiment was conducted to study the relation between the equilibrium moisture contents and the hygroscopic components in the various tobacco matters such as NC-82, Br-21, R.T.S., and puffed stem. The order of the high equilibrium moisture contents was the puffed stem, R.T.S., NC-82, and Br-21. The H-1 grades of NC-82 and Br-21 contained high contents of total sugar had higher equilibrium moisture contents than others. The moisture contents in NC-82 and Br-21 were increased at higher temperature, $30^{\circ}C$ than $20^{\circ}C$. The grades with high amounts of water extracts and total sugar affected to increase the equilibrium moisture contents in NC-82 and Br-21. In conclusion, the equilibrium contents were related to the structure of tobacco matter, the grades, the temperature, and the amount of some chemical components such as water extracts and total sugar of the leaf tobacco.

• Journal of the Korean Society of Marine Environment & Safety
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• v.11 no.2 s.23
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• pp.103-108
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• 2005

For the development of a disk type oil skimmer for a tank lorry, a basic study on comparison of oil recovery performance between disk materials of oil skimmer was conducted. The experiment results are summarized as follows: In all the disks, the volume of recovery of bunker-A oil was greater than diesel oil. In light oil, there was nearly no differences in the volume of oil recovery by disk material, but in the case of bunker A oil, recovery efficiency showed big differences depending on the disk materials. For diesel oil, the differences in the volume of oil recovery per unit of operation time from the initial time zone were hardly shown. However, the volume of recovery of bunker-A oil linearly increased from the initial operation time in all the disks and the increase showed a slew moving trend as time. went on; therefore, the volume of oil recovery per unit of operation time showed differences depending on time. This result shows that oil viscosity has an effect on the disk recovery efficiency. When comparing the mass of pure oil recovery and the volume of water recovery in the total mass of recovery by bunker-A oil, there was no difference in the volume of oil recovery between the window-aluminum material disk and the disks consisting of other materials, but the volume of water recovery of the former was relatively very small This shows the most ideal result in view of oil recovery efficiency that considers the volume of water recovery. In conclusion, it was found that aluminum is the most advantageous as the material for tank lorry oil skimmer disk.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.113-119
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• 2009

This study is to investigate the fundamental and fireproof qualities of high strength concrete corresponding to changes in the curing factors and the PP fiber ratio. The results were as follows. For the fundamental characteristics of concrete, the fluidity was reduced in proportion to the increase in the PP fiber ratio. The compressive strength was somewhat reduced according to an increase in the PP fiber ratio. However, it had the high strength scope of more than 60 MPa at 7 days and of more than 90 MPa at 28 days. On the spalling mechanism followed by changes of the water content ratio, spalling was prevented in all combinations, except the specimen without PP fiber and subjected to 3.0% of moisture contents. When spalling was prevented at that time, the residual compressive strength ratio was 22%~41% and the mass reduction ratio was 5%~7%, which was relatively favorable. As the spalling mechanism corresponds to changes in the curing method, spalling was prevented in concrete with a PP fiber mixing ratio of more than 0.05% in the event of standard curing, and in concrete with a PP fiber mixing ratio of more than 0.10% in the case of steam curing and autoclave curing. In these cases, when spalling was prevented, the residual compressive strength ratio was 23~42% and the mass reduction ratio was 7~11%. In these results, the ease of spalling prevention in high strength concrete was inversely proportional to the water content ratio. Depending on the curing method, spalling was prevented in concrete with over 0.05% PP fiber with standard curing and in concrete with over 0.1% PP fiber with steam curing and autoclave curing.

• Food Science and Preservation
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• v.11 no.2
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• pp.263-268
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• 2004

Two field cooling tests were conducted to evaluate the cooling characteristic of paddy with a prototype grain cooler. The first test was carried out during summer season in a steel bin with 180.3ton of paddy at Sunchon. And the second test was carried out during harvesting season in a steel bin with 272.2ton of paddy at Ulsan. At the first test, initial paddy temperature of 23.6$^{\circ}C$ was dropped to 14$^{\circ}C$, and initial moisture content of 19.9% was dropped to 19.3% after 52.5 hours of cooling. At the second test, initial paddy temperature of 16.1$^{\circ}C$ dropped to 5.5$^{\circ}C$ after 78.0 hours of cooling. And, at the first test, the average air flow rates of chilled air leaving the grain cooler and penetrating the grain layer were 77.5 ㎥/min and 42.5 ㎥/min, respectively. To prevent leakage of chilled air from plenum chamber of steel bin, which was about 45% of the average air flow rates of chilled air leaving the grain cooler, a proper method was required. The average total power consumption at the first test during summer was 22.1 ㎾ with control of fan damper. At the second test, it was 17.4 ㎾ due to controlling the capacity of compressor with unloading solenoid valve and changing the flow rates of hot refrigerant gas flowing into evaporator and reheater from compressor, resulting in 27% reduction of energy consumption.

• Korean Journal of Agricultural Science
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• v.12 no.1
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• pp.86-100
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• 1985

In order to investigate the strength characteristics of weathered granite soils in unsaturated state, the five physically different weathered granite soils and the common soil (sandy loam) were examined. The disturbed and the undisturbed material were prepared for triaxial compression test. The following conclusions were drawn from the study; 1. Dry density of the undisturbed soil samples was lower than maximum dry density determined from the compaction test and it showed the higher value at the well graded soil. 2. The failure strength of the samples decreased with the increase of moisture content of the soil and these results were highly pronounced at the common soil sample having a good cohesive property. 3. On weathered granite soils, the cohesion was lower measured and the internal friction angle highly, the decrease rate at internal friction angle with increase of moisture content of the soil was more significant than that of cohesion 4. The modulus of deformation of the samples decreased with increase of moisture content of the soil and these phenomena were highly pronounced at the weathered granite soils than common soil. 5. The failure strength of the samples increased with in crease of confining pressure and effect of confining pressure on failure strength was highly significant at the lower moisture content of the soil.

• Journal of the Korea Society of Computer and Information
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• v.14 no.5
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• pp.183-193
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• 2009

Both On-Line Analytical Processing (OLAF) data cubes and Statistical Databases (SDBs) deal with multidimensional data sets. and both are concerned with statistical summarizations over the dimensions of the data sets. However, there is a distinction between the two that can be made. While SDBs are usually derived from other base data, OLAF data cubes often represent directly the base data. In other word, the base data of SDBs are the macro-data, whereas the core cubiod data in OLAF data cubes are the micro-data. The base table in OLAF is used to populate the data cube with values of the measure attribute, and each record in the base tables is used to populate a cell of the core cuboid. The fact that OLAF data cubes mostly represent the micro-data may make some records be absent in the base table. Some cells of the core cuboid remain empty, if corresponding records are absent in the base table. Wang and others proposed a method for securing OLAF data cubes against privacy breaches. They assert that the proposed method does not depend on specific types of aggregation functions. In this paper, however, it is found that their assertion on aggregate functions is wrong whenever any cell of the core cuboid remains empty. The objective of this study is to design an inference control process in OLAF data cubes which rectifying Wang's error.