• Korea-Australia Rheology Journal
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• v.16 no.3
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• pp.147-152
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• 2004

Ultrasound-assisted melt mixing was applied to blending polystyrene (PS) and low density polyethylene(LDPE). The influence of the ultrasonic irradiation on the morphology and mechanical properties of the blends was investigated. It was observed that the domain sizes of the blend were significantly reduced and phase stability was well sustained even after a thermal treatment. Such morphological feature was consistent with the improvements in mechanical performance of the blends. The desirable results of ultrasonic compatibilization are mainly attributed to the in-situ formation of PS-LDPE copolymers as confirmed by a proper separation experiment. An important relationship between ultrasonic irradiation time and mechanical properties is revealed and an issue on the thermal stability of the blend is discussed.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1290-1291
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• 2006

Fabrication of $Fe_3AlC$ matrix in-situ composite, reinforced by a FeAl phase, was studied by using the powder metallurgical processing route. Especially, in order to disperse the second phase more finely, we chose the mechanical alloying process. We investigated the microstructural and mechanical properties of the consolidated material. After consolidation by vacuum hot pressing, the compact showed almost full density and consisted of a $Fe_3AlC$ matrix and FeAl second phase (average particle size was less than 1m). The compact showed HV746, which was higher than that of the arc melted $Fe_3AlC$ monolithic material, HV603.

• Progress in Superconductivity
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• v.6 no.1
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• pp.13-18
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• 2004

High-.ate in-situ$ YBa_2$Cu$Cu_3$$O_{7-x}$ (YBCO) film growth was demonstrated by means of the electron beam co-evaporation. Even though our oxygen pressure is low, ∼$5 ${\times}$10^{-5}$ Torr, we can synthesize as-grown superconducting YBCO films at a deposition rate of around 10 nm/s. Relatively high temperatures of around 90$0^{\circ}C$ was necessary in this process so far, and it suggests that this temperature at a given oxygen activity allows a Ba-Cu-O liquid formation along with an YBCO epitaxy. Local critical current density shows a clear correlation with local resistivity. Homogeneous transport properties with a large critical current density ($4 ∼ 5 MA/\textrm{cm}^2$ at 77K, 0T) are observed in top faulted region while it is found that the bottom part carries little supercurrent with a large local resistivity. Therefore, it is possible that thickness dependence of critical current density is closely related with a topological variation of good superconducting paths and/or grains in the film bodies. The information derived from it may be useful in the characterization and optimization of superconducting films for electrical power and other applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1112-1115
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• 2007

Optical thickness method using double interferometer showed dynamic variations of both mechanical and optical thicknesses. Packing density measured a thickness ratio of before and after pressed single film. Lower swelled thickness of emitting layer in a device and densely packed film had shown better lifetime.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.65-71
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• 1996

A novel lateral field emitter triode has been designed and fabricated. It has self-vacuum environmets and low turn-on voltage, so that the chief problems of previous field emission devices such as additional vacuum sealing process and high turn-on voltage are settled. An in-situ vaccum encapsulation empolying recessed cavities by isotropic RIE (reactive ion etch) method and an electron beam evaporated molybdenum vacuum seals are implemented to fabricate the new field emitter triode. The device exhibits low turn-on voltage of 7V, stabel current density of 2.mu.A/tip at V$_{AC}$ = 30V, and high transconductance (g$_{m}$) of 1.7$\mu$S at V$_{AC}$ = 22V. The superb device characteristics are probably due to sub-micron dimension device structure and the pencil type lateral cathode tip employing upper and lower LOCOS oxidation.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.41-48
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• 2000

Most land development projects and large scale civil works require a great amount of sand. And sand is also the most favorable material for soft ground improvement. The demand for sand is soaring rapidly due to increased number of projects regardless of its limited supply. Therefore, it is not difficult to predict that sand may become depleted and no longer be available as ground improvement material in the near future. Against this backdrop, developing an inexpensive sand-substitution material with an efficient accessibility will be necessary and urgently called for. So quick lime could be recommended as the substitutional material for sand. Quick lime is now preferred by forward developed nations. If Korea is able to take advantage of its abundant supply, economical efficiency could be achieved through massive production as well as being able to take advantage of utilization of natural resources. In this respect the purpose of this paper was to estimate improvement effect of soft ground though in-situ construction of quick lime pile. In-situ construction was peformed in road construction site of soft clay and in this study quick lime from Dan-yang that was estimated prominently in aspect of engineering characteristics was used. Quick lime piles were installed by 1.5m, 2.0m, 3.0m spacing to confirm improvement effect according to spacing and installed piles are 0.4m in diameter, up to 5m in length and the density of quick piles installed is 1.4 t/㎥. Vibrating wire pore water pressure cell was installed to confirm consolidation characteristics in surrounding of quick lime piles and both laboratory test and field test were carried out to confirm strength increase. In conclusion, soft ground improvement by quick lime piles was confirmed.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.47-53
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• 2015

The effects of electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the in-situ intermetallics reaction and the electromigration (EM) reliability of Sn-3.0Ag-0.5Cu (SAC305) solder bump were systematically investigated. After as-bonded, $(Cu,Ni)_6Sn_5$ intermetallic compound (IMC) was formed at the interface of the ENIG surface finish at solder top side, while at the OSP surface finish at solder bottom side,$ Cu_6Sn_5$ and $Cu_3Sn$ IMCs were formed. Mean time to failure on SAC305 solder bump at $130^{\circ}C$ with a current density of $5.0{\times}10^3A/cm^2$ was 78.7 hrs. EM open failure was observed at bottom OSP surface finish by fast consumption of Cu atoms when electrons flow from bottom Cu substrate to solder. In-situ scanning electron microscope analysis showed that IMC growth rate of ENIG surface finish was much lower than that of the OSP surface finish. Therefore, EM reliability of ENIG surface finish was higher than that of OSP surface finish due to its superior barrier stability to IMC reaction.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1230-1231
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• 2008

The effect of content of $Al_2O_3+Y_2O_3$ sintering additives on the densification behavior, mechanical and electrical properties of the pressureless-sintered $SiC-ZrB_2$ electroconductive ceramic composites was investigated. The $SiC-ZrB_2$ electroconductive ceramic composites were pressureless-sintered for 2 hours at 1,700[$^{\circ}C$] temperatures with an addition of $Al_2O_3+Y_2O_3$(6:4 mixture of $Al_2O_3$ and $Y_2O_3$) as a sintering aid in the range of 8${\sim}$20[wt%]. Phase analysis of $SiC-ZrB_2$ composites by XRD revealed mostly of ${\alpha}$-SiC(6H), $ZrB_2$ and In Situ YAG($Al_5Y_3O_{12}$). The relative density, flexural strength, Young's modulus and vicker's hardness showed the highest value of 89.01[%], 81.58[Mpa], 31.437[GPa] and 1.34[GPa] for $SiC-ZrB_2$ composites added with 16[wt%] $Al_2O_3+Y_2O_3$ additives at room temperature respectively. Abnormal grain growth takes place during phase transformation from ${\beta}$-SiC into ${\alpha}$-SiC was correlated with In Situ YAG phase by reaction between $Al_2O_3$ and $Y_2O_3$ additive during sintering. Compositional design and optimization of processing parameters are key factors for controlling and improving the properties of SiC-based electroconductive ceramic composites. In this paper, it is convinced that ${\beta}$-SiC based electroconductive ceramic composites for heaters or ignitors can be manufactured by pressureless sintering.

• Clinical and Experimental Reproductive Medicine
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• v.21 no.1
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• pp.121-130
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• 1994

Expression of gonadotropin releasing hormone(GnRH) has been described in the rat ovary. It remains, however, unkown whether GnRH is synthesized as a prohormone. Therefore, this study was performed to verify the expression of pro-GnRH by in situ hybridization and further to investigate the effect of gonadotropin on GnRH or GnRH mRNA in rat ovary by immunohistochemical and in situ hybridization techniques. Adult female Sprague-Dawely rats were used and the estrous cycle was synchronized by intraperitoneal injection of pregnant mare's serum gonadotropin(PMSG). Ovaries were fixed with 4% paraformaldehyde and embedded with G.C.T. compound and cut by cryostat. For immunohistochemistry, avidin-biotin peroxidase complex(ABS) method was employed and for in situ hybridization, $^{35}S$-end labeled oligonucleotide was used and followed by autoradiography. By in situ hybridization using GnRH oligomer and GAP(GnRH associated protein) oligomer, GnRH mRNA and GAP mRNA were co-localized in the fullicular cells, luteal cells, interstitial cells and theca cells. GnRH or GnRH mRNA signals in the ovary increased by human chorionic gonadotropin(hCG) injection. At the 3 and 6 hrs after hCG injection, the number of GnRH and GnRH mRNA containing cells increased rapidly and the density of GnRH and GnRH mRHA culminated at 9 hrs after heG injection. With the follicular development, the high expression of GnRH and GnRH mRNA was also observed within the follicles. After ovulation, the density of GnRH or GnRH mRNA decreased in the follicles but increased in the corpus lutea.

• Journal of Embryo Transfer
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• v.22 no.3
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• pp.173-178
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• 2007

돼지 정자의 성 선별에는 일반적으로 유속 세포 분석기를 이용한다. 유속 세포 분석은 DNA량의 차이에 기초하여 정자를 분리하는 기술로써 X 정자와 Y 정자를 90% 정확도로 분리할 수 있다. 그러나 이러한 유속 세포분석 기술은 정자의 손상을 야기해 정자의 기능과 수정능에 영향을 미치므로, 본 연구에서는 특정한 핵산 서열을 탐지할 수 있는 Chromogenic in situ hybridization(CISH)을 그와 비교하여 평가하였다. 유속 세포 분석을 수행하기 위해 정자를 SYBR 14와 PI로 염색하였고, histogram, dotplot, density, contour를 측정하였다. Y 염색체 특이적인 primer를 이용한 PCR로 유속 세포 분석의 정확도를 검사하였다. HRP/DAB 시스템에 기초한 CISH 분석에는 X 또는 Y 염색체에 상보적으로 결합하는 probe가 사용되었다. CISH 분석은 기존의 방법들보다 빠르고 쉬우며 비용이 적게 든다는 장점이 있다. 또한, CISH는 보다 정화한 정자의 선별을 가능하게 하는 것으로 나타났다. 본 연구에 따르면 CISH가 기존의 선별 방법들을 평가하는 기술로서만이 아니라 특정한 성별을 가진 포유동물의 생산에도 사용될 수 있을 것이다.