• Geomechanics and Engineering
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• 제2권3호
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• pp.177-190
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• 2010

This paper presents the details of indigenous development of the piezovibrocone and calibration chamber. The developed cone has a cylindrical friction sleeve of $150cm^2$ surface area, capped with a $60^{\circ}$ apex angle conical tip of $15cm^2$ cross sectional area. It has a hydraulic shaker, coupled to the cone penetrometer with a linear displacement unit. The hydraulic shaker can produce cyclic load in different types of wave forms (sine, Hover sine, triangular, rectangular and external wave) at a range of frequency 1-10 Hz with maximum amplitude of 10 cm. The piezovibrocone can be driven at the standard rate of 2 cm/sec using a loading unit of 10 ton capacity. The calibration chamber is of size $2m{\times}2m{\times}2m$. The sides of the chamber and the top as well as the bottom portions are rigid. It has a provision to apply confining pressure (to a maximum value of $4kg/cm^2$) through the flexible rubber membrane inlined with the side walls of the calibration chamber. The preliminary static as well as dynamic cone penetration tests have been done sand in the calibration chamber. From the experimental results, an attempt has been made to classify the soil based on friction ratio ($f_R$) and the cone tip resistance ($q_c$).

• 산업기술연구
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• 제3권
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• pp.87-94
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• 1983

Heating characteristics of red pepper paste packed in report pouches of various thicknesses and their storage stability were investigated to determine the adequate processing conditions that good bacteriological safty and minimal quality changes could be obtained, when sterilized by using a steam-air system retort. A heat penetration into pouch-packed red pepper paste was carried out through by a conductive heat transfer, indicating a simple logarithmic heating curve, and the smaller thickness revealed the higher heat penetration rate, suggesting the possibility of high temperature-short time sterilization of red pepper paste. The processing conditions with Fo-value of 4.5 or higher were sufficient for keeping up bacterial safty, but based on C-value, better quality retention was obtained at pouch thickness of 15mm under the processing temperature of $120^{\circ}C$. Subsequent storage study revealed that the red pepper paste packed in 15mm and processed at $120^{\circ}C$ with Fo=4.5 could be held without any spoilage and overall acceptance change, when stored for 6 months at room temperature under the relative humidity of 70%. After 3 months storage in $38^{\circ}C$ under saturation humidity, overall acceptance of red pepper paste were judged not to be maintainable on the acceptable level, but it may be suggested that above the results could be kept up a desirable quality without any remarkable deterioration.

• 설비공학논문집
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• 제27권8호
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• pp.409-417
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• 2015

A simplified rotary heat-exchanger model was developed with an assumption of a linear temperature distribution along the flow direction. Based on the model, the exact fluid solution and solid temperature variations were obtained and verified from a comparison with previous numerical studies. The heat transfer in the rotary heat exchanger was investigated using the theoretical solutions. The heat exchanger's effectiveness was shown to be saturated, with a rotational-speed increase that is higher than a critical value that is solely dependent on the thermal capacity of the solid matrix but independent of the fluid flow rate; the saturated value of the effectiveness was determined only by the NTU of the heat exchanger. Where the thermal diffusivity of the solid matrix is so slight that the thermal penetration depth becomes smaller than the matrix thickness, the effective thermal capacity of the solid matrix decreased according to the penetration depth.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.312-333
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• 2006

This paper presents the results of an analysis of the excess porewater pressure distribution due to piezocone penetration in overconsolidated clays. From piezocone test results for moderately and heavily overconsolidated clays, it was observed that the excess porewater pressure increases monotonically from the piezocone surface to the outer boundary of the shear zone and then decreases logarithmically to the outer boundary of the plastic zone. It was also found that the size of the shear zone decreases from approximately 2.2 to 1.5 times the cone radius with increasing OCR, while the plastic radius is about 11 times the piezocone radius, regardless of the OCR. The equation developed in this study based on the modified Cam clay model and the cylindrical cavity expansion theory, which take into consideration the effects of the strain rate and stress anisotropy, provide a good prediction of the initial porewater pressure at the piezocone location. The method of predicting the spatial distribution of excess porewater pressure proposed in this study is based on a linearly increasing ${\Delta}u_{shear}$. In the shear zone and a logarithmically decreasing ${\Delta}u_{oct}$, and is verified by comparing with the excess porewater pressure measured in overconsolidated specimens at the calibration chamber.

• 한국수정란이식학회지
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• 제15권1호
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• pp.95-102
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• 2000

Techniques for manipulation of spermatozoa and oocytes have been widely used for in vitro production(IVP) of Hanwoo. This study was conducted to examine the effects of theophylline and heparin on frozen-thawed Hanwoo sperm for enhancing the efficiency of IVP technique. Oocytes were inseminated with forzen bull semen treated with either theophylline or heparin for examining the effect of each substance on fertilization and subsequent development. More (P<0.05) oocytes formed pronucleus and develop to the morula and blastocyst stages after inseminated with sperm treated with heparin than after inseminated with sperm treated with theophylline. The pregnancy rate after embryo transfer was higher after heparin treatment than after theophylline treatment, but did not differ significantly. There was no significant difference of offspring delivery between two groups. In conculsion, theophylline and heparin can be used for enhancing the efficiency of IVP system for Hanwoo. Considering characteristics of these substance, theophylline may be useful in the artificial insemination system, which requires vigorous sperm motility. While, heparin supporting sperm viability in vitro can be effectively used for improving in vitro-fertilization system.

• Journal of Biosystems Engineering
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• 제12권3호
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• pp.1-6
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• 1987

The objective of this study is to develop a soil hardness tester which can estimate tillage resistance with tae travelling cone-penetrometer. For the study, a series of tests was performed using the cone penetrating in the horizontal direction. Based on the tests above, soil hardness was represented by travelling cone-index vs depth of cone penetration, travelling speed and moisture contents of the soil Resistance characteristics obtained from the experiments were compared with those by a vertical cone-penetrometer and the Yamanaka's soil hardness tester. Following conclusions were made from the study. 1. 8 to 9 peaks per one meter were detected in the resistance curve of cone penetration regardless of the travelling speed of cone-penetrometer when it penetrated the soil in the horizontal direction. This phenomenon seemed to be a similar one noticed in shearing pitch of plowing. 2. Cone index increased as travelling speed increased from 0.08m/sec to 0.5m/sec. 3. Linear relationship was found between the cone indices measured by the travelling coe-penetrometer and Yamanaka's hardness tester. 4. Increasing rate of the cone indices measured by vertical cone-penetrometer decreased as the depth of soil increased while the cone indices by the travelling cone-pentrometer increased linearly.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.3596-3601
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• 2015

진동해머에 의해 시공되는 말뚝의 거동을 분석할 목적으로 개발된 기존의 프로그램을 개선하고자 하였다. 진동해머-말뚝-지반으로 구성되는 진동시스템의 기존 지배방정식에 지반저항의 댐핑효과와 클러치마찰력을 추가하였다. 또한, 개발된 해석기법의 하중전이곡선을 모사하는 수정 Ramberg-Osgood 모델의 매개변수를 재산정하여 해석기법을 개선하고자 하였다. 수정된 프로그램에 의한 해석결과를 현장시험결과와 비교해 볼 때 시간에 따른 말뚝의 변위 및 하중전이거동이 현장시험결과에 좀 더 유사하였다. 개발된 프로그램에 의한 말뚝 관입깊이별 관입속도를 상용 프로그램에 의한 결과 및 현장시험결과와 비교해 볼 때 상용프로그램보다 훨씬 더 현장시험결과에 가까웠다.

• Clinical and Experimental Reproductive Medicine
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• 제47권3호
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• pp.186-193
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• 2020

Objective: The effectiveness of Staphylococcus protein A (SPA) in improving the penetration ability of sperm and reducing antisperm antibody (ASA) titers in immunologically infertile males was evaluated. Methods: Seminal fluid samples were obtained from 15 infertile men, and ASA titers were assessed with the latex agglutination test. Identification of immunoglobulin (Ig) classes and characterization of the antigens involved in the immune response were performed using indirect immunofluorescence. Local ASAs typically present as a mixture of IgG and IgA classes. The capillary tube penetration method was used to assess the capability of spermatozoa to penetrate the cervical mucus (CM). Results: ASAs associated with the neck region of sperm showed a significantly lower migration distance in the CM of infertile females than ASAs associated with the head or tail segments. ASA-positive seminal fluid exhibited significant increases in the mean migration distance (2.6 ± 1.4 cm vs. 1.54 ± 1.1 cm, respectively; p< 0.001) and sperm concentration (174 ± 121.0 × 10³/mL vs. 101 ± 93.7 × 10³/mL, respectively; p= 0.033) after treatment with SPA compared to pre-treated samples. A significant reduction (p< 0.01) in the recorded ASA titer was detected. Conclusion: These results indicate that SPA can be used as a sorting regimen for insemination programs. However, further studies are warranted to assess its influence on pregnancy rate.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.13-14
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• 2005

Multi-dimensional combustion analysis and experiment has been carried out to investigate the effects of the injector nozzle hole diameter and number on the NOx formation and fuel consumption in HYUNDAI HiMSEN engine. The behavior of spray and combustion phenomena in diesel engine was examined by FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation. Wallfilm model suggested by Mundo, et al. and auto-ignition model suggested by Theobald and Cheng were adopted to investigate the spray-wall interaction characteristics and ignition delay. The information of spray angle and spray tip penetration length was extracted from fuel spray visualization experiment and the fuel injection rate profile was extracted from fuel injection system experiment as an input and verification data for the combustion analysis. Next, the nine different nozzle configurations were simulated to evaluate the effect of injector hole diameter and number on the NOx formation and fuel consumption.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1154-1159
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• 2004

Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional arc welding processes, leading to a rather small weld zone. Experiments are performed for Inconel 600 plates changing several process parameter such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between plate and plate, etc. The follow conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/ aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power . Welding characteristics of austienite Inconel 600 using a continuous wave Nd:YAG laser are experimentally investigated. This paper describes the weld ability of inconel 600 for machine structural use by Nd:YAG laser.