• Korean Journal of Materials Research
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• v.22 no.10
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• pp.545-551
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• 2012

In semiconductor manufacturing, the circuit integrity of packaged BGA devices is tested by measuring electrical resistance using test sockets. Test sockets have been reported to often fail earlier than the expected life-time due to high contact resistance. This has been attributed to the formation of Sn oxide films on the Au coating layer of the probe pins loaded on the socket. Similar to contact failure, and known as "fretting", this process widely occurs between two conductive surfaces due to the continual rupture and accumulation of oxide films. However, the failure mechanism at the probe pin differs from fretting. In this study, the microstructural processes and formation mechanisms of Sn oxide films developed on the probe pin surface were investigated. Failure analysis was conducted mainly by FIB-FESEM observations, along with EDX, AES, and XRD analyses. Soft and fresh Sn was found to be transferred repeatedly from the solder bump to the Au surface of the probe pins; it was then instantly oxidized to SnO. The $SnO_2$ phase is a more stable natural oxide, but SnO has been proved to grow on Sn thin film at low temperature (< $150^{\circ}C$). Further oxidation to $SnO_2$ is thought to be limited to 30%. The SnO film grew layer by layer up to 571 nm after testing of 50,500 cycles (1 nm/100 cycle). This resulted in the increase of contact resistance and thus of signal delay between the probe pin and the solder bump.

• New & Renewable Energy
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• v.8 no.3
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• pp.30-37
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• 2012

In this study, we studied solar cell and fuel cell. To estimate the technology competitiveness, we used patent analysis using patent information and delphi method. For patent analysis, PII indicating the impact of patent was used. Also to analysis PII, citations data of registered and published patent were used from 2001 through 2010 in the United States, Japan, South Korea and the European Patent Office. And the delphi method results of the 'International trend analysis on the Green Energy Technology and the establishment of international cooperation models(2009)' were cited to estimate the technology level. According to the analysis results, Korea's patent registration growth rate was fairly high, but the patent impact and technology levels were significantly lower than in the United States, Japan and Germany. Especially in the solar cell, United States's PII is 1.8, but Korea's PII is 0.2. And the technology level of United States is 7 to 8, but Korea's is 5 to 6. Therefore, to improve technology competitiveness, Korea need to enhance the core technology R&D, and set up the consumer-oriented R&D strategy for commercialization from R&D planning phase. In this study, we analysed competitiveness of renewable energy which is not actively discussed. But there are limitations of the study because we used the result of past research and patent data in the past 10 years. Therefore to accurate research the period of patent data should be extended. Finally diverse indicators for measuring the technology competitiveness should be researched and developed.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.1112-1120
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• 2017

Petroleum products are composed of various types of hydrocarbon compounds. Like other types of liquids, they presented the variation of density and volume according to temperature change. The method of measuring the density of petroleum products in a liquid phase is based on experimental data obtained mainly for each fractionally distilled petroleum product. In this study, the density and volume changes of kerosene and automotive diesel according to temperature change were measured and the property of change were analyzed. The conversion values were calculated using the density volume conversion table proposed by international standard ASTM. In addition, we analyzed the differences between the reference values and the measured values for the temperature changes specified in the domestic metering law.

• The KIPS Transactions:PartD
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• v.16D no.4
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• pp.549-560
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• 2009

The Agile movement is a phenomenon that is part of the next phase of the software engineering evolution. At the same time, globally distributed software development is another trend delivering high-quality software to global users at lower costs. In this paper, Agile Framework for Distributed Software Development (AFDSD) has been suggested, and Chameleon project of Yahoo! Inc. has been implemented based on the framework. Also, the project has been evaluated by measuring Agile adoption and improvement levels, degrees of agility and agile project success, and comparing the performance and quality with the previous version. The overall performance and satisfaction with Chameleon increased by more than 30% since Agile techniques were adopted. Our objective is to highlight successful practices and suggest a framework to support adoption and evaluation of Agile techniques in a distributed environment.

• Preventive Nutrition and Food Science
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• v.3 no.2
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• pp.143-151
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• 1998

Protein -surfactant interactions have been investigate by measuring ζ-potential of $\beta$-lactoglobulin-coated emulsion droplets and $\beta$-lactoglobulin in solution in the rpesenceof surfactant, with particular emphasis on the effect of protein heat treatment(7$0^{\circ}C$, 30min). When ionic surfactant (SDS or DATEM) is added to the protein solution, the ζ-potential of the mixture is found to increase with increasing surfactant concentration, indicating surfactant binding to the protein molecules. For heat-denatured protein,it has been observed that the ζ-potential tends to be lower than that of the native protein. The effect of surfactant on emulsions is rather complicated .With SDS, small amounts of surfactant addition induce a sharp increase in zeta potential arising from the specific interaction of surfactant with protein. With further surfacant addition, there is a gradual reductio in the ζ-potential, presumably caused by the displacement of adsorped protein (and protein-surfactant complex) from the emulsion droplet surfac by the excess of SDS molecules. At even higher surfactant concentrations, the measured zeta potential appears to increase slightly, possibly due to the formation of a surfactant measured zeta potential appears to increase slightly, possibly due to the formation of surfactant micellar structure at the oil droplet surface. This behaviour contrastswith the results of the corresponding systems containing the anionic emulsifier DATEM, in which the ζ-potential of the system is found to increase continuously with R, particularly at very low surfactant concentration. Overall, such behaviour is consisten with a combination of complexation and competitive displacement between surfactant and protein occurring at the oil-water interface. In addition, it has also been found that above the CMC, there is a time-dependent increase in the negative ζ-potential of emulsion droplets in solutions of SDS, possibly due to the solublization of oil droplets into surfactant micelles in the aqueous bulk phase.

• Journal of the Korean GEO-environmental Society
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• v.6 no.1
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• pp.23-31
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• 2005

The "Silt Pond" is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Reclamation works in the Silt Pond commenced in the mid of 1990s. A considerable amount of subsurface investigation inclusive of sampling, field vane and density logging tests were carried out prior to the reclamation of the Silt Pond. Since material in the Silt Pond is extremely soft, filling was done by spreading sand with high water content in thin and equal thickness lifts, allowing the stability of the slurry-like foundation. Despite the extreme care taken, failures occurred during the sand spreading phase. A large piece of high strength geotextile measuring $900m{\times}700m$ was placed to strengthen the slurry like soil foundation at locations where the ultra-soft soil was found to be exposed. Following the remedial works, the Silt Pond was again reclaimed by sand spreading up to +4.0m CD. The success of the reclamation was confirmed by marine CPT profiling.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.985-990
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• 2007

The method of enhancing visibility in optical fiber sensor was investigated by improving coherence length of light source. The optical feedback technique is used to enhance coherence length in fiber laser which generates laser in near infrared wavelength region and utilizes low loss characteristics of optical communication grade fiber. In this paper, the effect to coherence length by short and long optical feedback paths are investigated by using Mach-Zehnder interferometer technique. The effect to coherence length by changing optical feedback power and optical modulation are investigated. The spectral drift was calculated by measuring the degree of phase perturbation in unbalanced Mach-Zehnder interferometer having loom path difference. The short optical feedback path was effective to reduce spectral drift to 450kHz/sec and the long optical feedback path in combination with short optical feedback path was found to further reduce spectral drift to 50kHz/sec.

• Korean Journal of Remote Sensing
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• v.13 no.2
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• pp.151-163
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• 1997

In this paper, an algorithm for retrieving soil moisture from measurement of microwave reflection at the end of a coaxial canble is presented. Because the wave reflection from the boundary between air and soil layers depends on the dielectric constant of the soil layer, the dielectric constant can be obtained from measured reflection coefficient. At first, an equivalent circuit for the coaxial probe contaced on the soil surface was chosen with two unknown circuit elements. Then, the unknown circuit elements are obtained experrmentally by measuring the reflection constants of 20 soil samples, and consequently, an empirical formula for computing the dielectric constant from the reflection coefficient is obtained. The dielectric constant is mainly influenced by the soil moisture, and the soil moisture can be computed from the dielecfic constant using an existing empirical formula. HP Network Analyzer 8510C was used to measure the magnitude and the phase of the reflection coeffcient at 4.65 GHz, and the measured data set were used to obtain an empirical formula for computing the dielectric constant. The empirical formula obtained in this study was proven by other soil samples.

• Korean Journal of Remote Sensing
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• v.26 no.3
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• pp.297-304
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• 2010

Since the change in Doppler centroid according to moving targets brings alteration to the phase in azimuth differential signals of synthetic aperture radar (SAR) data, one can measure the velocity of the moving targets using this effect. In this study, we will investigate theoretically measuring the velocity of an object from azimuth differential signals by using range compressed data which is the interim outcome of treatment from the simulated SAR raw data of moving targets on the background of sea clutter. Also, it will provide evaluation for the elements that affect the estimation error of velocity from a single SAR sensor. By making RADARSAT-1 simulated image as a specific case, the research includes comparisons for the means of velocity measurement classified by the directions of movement in the four following cases. 1. A case of a single target without currents, 2. A case of a single target with tidal currents of 0.5 m/s, 1 m/s, and 3 m/s, 3. A case of two targets on a same azimuth line moving in a same direction and velocity, 4. A case of a single target contiguous to land where radar backscatter is strong. As a result, when two moving targets exist in SAR image outside the range of approximately 256 pixels, the velocity of the object can be measured with high accuracy. However, when other moving targets exist in the range of approximately 128 pixels or when the target was contiguous to the land of strong backscatter coefficient (NRCS: normalized radar cross section), the estimated velocity was in error by 10% at the maximum. This is because in the process of assuming the target's location, an error occurs due to the differential signals affected by other scatterers.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.3
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• pp.86-93
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• 2011

Recently, development and application of condition monitoring and diagnostic system for improvement of durability and reliability and reduction of operating cost is generalized in the aircraft propulsion system. Expecially, for reliable operation of the high altitude and a long time and condition monitoring system to identify faults and degradations of its propulsion system should be needed. This work proposed a GUI-based On-line condition monitoring program using LabVIEW by PT6A-67 turboprop engine. The proposed on-line condition program can monitor the real engine performance as well as the trend through precise comparison between performance results calculated by the base performance simulation program and measuring engine performance signals. In the development phase of this monitoring system, a signal generation module is proposed to evaluate the proposed on-line monitoring system.