• 한국농공학회지
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• 제13권3호
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• pp.2342-2348
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• 1971

In concrete, the mater over aggregate is ever demanding each year in paralled with rapid development of Construction works from a couple of years ago. Want of most of them which is river gravel among aggregate has made us uneasy to get good gravel in quality. So far, we have counted on gravel, however, the time to turn the use of normal concrete into that of crushed concrete is closing at hand, I think. According to the results of study by Kaplan, Zeitman, Murdock, Hanada, Yamamodo, the shape of aggregate particle have a great effect on workability of concrete, as we know, is well known to the world. Crushed stone, particularly, is inconvenient to handle on account of jagged, angled particle form and rugged surface structure, give rise to inpediments in works, its unit water stands at about $15-20kg/m^3$, and w/c shows the increasing rate of approximately 5-10%, but it is unsuitable to use in terms of regidity. In order to research all of these, I have experimentalized and reviewed the physical character of aggregate and the regidity of concrete, in addition, its relative ratio of the elastic disposition as to gravel and crushed stone.

• 미생물학회지
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• 제20권1호
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• pp.27-40
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• 1982

The effects of heavy metals on the growth rate and phosphate metabolism of Chlorella elliposidea cells were investigated. Chlorella cells were cultured in the media treated with Hg(0.3, 0.7, 0.9 ppm), Cd(1, 5, 15ppm), and Zn(1, 5, 50ppm) for 6days. Aliquots cells were taken out at the inoculation and at intervals during the culture, and measured packed cell vlolume and optical density. The inhibitions of heavy metals on the growth rate and chlorophyll contents were traced. Also after 6 days culture, the amounts of inorganic phosphate and organic compounds of various fractions in Chlorella cells were observed. The turbid effects of heavy metals on the growth rate and chlorphyll contents of Chlorella cells were in order of Hg>Cd>Zn. Because heavy metals depressed the biosynthesis of inorganic polyphosphates and nucleic acids and turn over of inorganic phosphates, the amounts of various phosphate compounds were decreased. The inhibitory effect of photosynthesis by heavy metals resulted in lower contents of carbohydrate. Due to the turbidity of biosynthesis of amino acids by heavy metals, contents of protein were reduced in comparison with those of control. It is suggested conciusively that the minimum concentrations affected by heavy metals on the growth rate and phosphate metabolism of Chlorella cells were 0.7 ppm Hg, 15ppm Cd, 50ppm Zn.

• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.474-483
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• 2011

Solid-state fault current limiters (SSFCL) in power systems are alternative devices to limit prospective short circuit currents from reaching lower levels. Fault current limiters (FCL) can be classified into two categories: R-type (resistive) FCLs and L-type (inductive) FCLs. L-type FCL uses an inductor to limit fault level and is more efficient in suppressing voltage drop during a fault. In contrast, R-type FCL is constructed with a resistance and is more effective in consuming the acceleration energy of generators during a fault. Both functions enhance the transient stability of the power system. In the present paper, a novel SSFCL is proposed to enhance power system transient stability and power quality. The proposed SSFCL uses both functions of an L-type and R-type FCL. SSFCL consists of four diodes, one self-turn-off IGCT, a current-limiting by-pass inductor (L), and a variable resistance parallel with an inductor for improvement of power system stability and prevention of over-voltage across SSFCL. The main advantages of the proposed SSFCL are the simplicity of its structure and control, low steady-state impedance, fast response, and the existence of R-type and Ltype impedances during the fault, all of which improve power system stability and power quality. Simulations are accomplished in PSCAD/EMTDC.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.792-801
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• 2005

This paper discusses a dc motor equipped electric power steering (EPS) system and demonstrates its advantages over a typical hydraulic power steering (HPS) system. The tire-road interaction torque at the steering tires is calculated using the 2 d.o.f. bicycle model, in other words by using a single-track model, which was verified with the J-turn test of a real vehicle. Because the detail parameters of a steering system are not easily acquired, a simple system is modeled here. In previous EPS systems, the assisting torque for the measured driving torque is developed as a boost curve similar to that of the HPS system. To improve steering stiffness and return-ability of the steering system, a third-order polynomial as a torque map is introduced and modified within the preferred driving torques researched by Bertollini. Using the torque map modification sufficiently improves the EPS system.

• ALGAE
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• 제26권1호
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• pp.51-60
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• 2011

Similar to other species of Gigartinaceae Chondrus crispus has an alternation of perennial, isomorphic gametophytic and sporophytic generations. As these two generations co-exist independently within populations and obtain their resources in a similar manner, intraspecific competition is expected. In populations within the southern Gulf of St. Lawrence, fronds of both generations of C. crispus occur in similar numbers. This equivalency can be related to substratum instability, where the population is dynamic with a high turn-over rate of genets. These observations support a stochastic hypothesis to account for distribution of gametophytes and sporophytes in this area. Along the Atlantic coast of Nova Scotia, where the substratum is stable, gametophytes are overwhelmingly predominant. Gametophytic predominance is greatest in the lower littoral zone where C. crispus is abundant and space is limited. Under the fucoid canopy where "free-space" exists, the gametophyte to sporophyte ratio is lower. Gametophytic and sporophytic fronds are distributed equally among different size-classes and size-distribution is not considered a competitive factor. Previous studies have shown that sporophytic fronds of C. crispus are more susceptible to infections by endophytic algae and other pathogens, and are more heavily grazed by herbivores than are gametophytic fronds. Thus, mechanistic factors are strongly implied in the selection of gametophytes in the Atlantic population.

• 대한의용생체공학회:의공학회지
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• 제37권5호
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• pp.178-185
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• 2016

Tear is a promising biological fluid for non-invasive health monitoring. It has been studied in the past to be a possible candidate for the diagnosis of certain systemic diseases, such as breast cancer, multiple sclerosis, prostate cancer, and diabetes. However, currently existing methods for collecting and extracting tear from the human eye causes inconsistencies in the biomolecule concentrations of the tear sample due to the irritating nature of the process. In response, we designed and fabricated a microfluidic system embedded soft contact-lens for the purpose of tear sampling. The lens was then tested with artificial tear for its tear sampling capability, and found to be able to find concentration equilibrium within 50 minutes. Additionally, simulation was carried out to further optimize the design so that tear sampling rate matched the natural tear turn-over rate of 1 microliter per minute.

• 패션비즈니스
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• 제17권3호
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• pp.99-108
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• 2013

The purpose of this study is to do a detailed analysis of the layouts and components of the main pages of the SOHO malls, which serve as its display window, and in turn, find a successful strategy for SOHO malls in the over saturated Internet shopping mall market. To analyze the components and layout of the main page of the SOHO Internet apparel shopping malls, top 50 Internet apparel shopping malls for woman and top 50 Internet apparel shopping malls for man, ranked within Internet shopping mall were selected. Data were collected from the coding sheets surveyed on the Internet apparel shopping malls for one month (September 2012). The result showed different patterns in various aspects between women's and men's malls. 1) The men's malls used product pictures more frequently in their main pages than the women's malls 2) The sections for jewelry and beauties were usually included in men's apparel shopping malls. 3) Men's malls usually had a rather crowded layout with numerous banners in order to expose their promotional items to the fullest. 4) men's malls provided a more detailed promotional and product information regarding the display items on its main pages. 5) Women's malls had a wider range of price distribution and generally higher prices.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.938-945
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• 2005

For elucidating excessive growth of biofilm that subsequently leads to the clogging problem in a small town's sewer lines of Wisconsin, the FISH method was employed. At the beginning of the simulated experiments, ${\beta}$-subclass proteobacteria prevailed in runs fed with industrial wastewater, while ${\gamma}$-subclass proteobacteria dominated in runs with domestic wastewater. However, the bacterial community structure changed significantly over six weeks; Cytophaga-Flavobacterium (CF)­group bacteria dominated in most runs fed with the small town's wastewater regardless of their source, while CF-group decreased strongly in run fed with domestic sewage from another city (Madison). It was also microscopically confirmed that most of those clogging materials was toilet tissue, which in turn may lead to vigorous growth of cellulose-degrading CF-group bacteria. This dominant presence of CF-group bacteria in the small town's sewer indicates that the main constituent of biofilm, toilet tissue (cellulose) in sewage, might have induced the unique pattern of their microbial community structure. Therefore, it suggests that molecular technique is useful for monitoring the clogging problems in sewer lines.

• Structural Engineering and Mechanics
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• 제21권1호
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• pp.67-82
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• 2005

This study analyzes stress intensity factors for a number of periodic edge cracks in a semiinfinite medium subjected to a far field uniform applied load along with a distribution of eigenstrain. The eigenstrain is considered to be distributed arbitrarily over a region of finite depth extending from the free surface. The cracks are represented by a continuous distribution of edge dislocations. Using the complex potential functions of the edge dislocations, a simple as well as effective method is developed to calculate the stress intensity factor for the edge cracks. The method is employed to obtain the numerical results of the stress intensity factor for different distributions of eigenstrain. Moreover, the effect of crack spacing and the intensity of the normalized eigenstress on the stress intensity factor are investigated in details. The results of the present study reveal that the stress intensity factor of the periodic edge cracks is significantly influenced by the magnitude as well as distribution of the eigenstrain within the finite depth. The eigenstrains that induce compressive stresses at and near the free surface of the semi-infinite medium reduce the stress intensity factor that, in turn, contributes to the toughening of the material.

• Journal of Nutrition and Health
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• 제34권7호
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• pp.770-777
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• 2001

This study investigated nutritional status and eating behaviors among 59 nephritic patients with mild kidney malfunction in Korea. Nutritional status was measured by blood analysis and 1-3 day dietary recall and records, and eating behaviors were assessed by a questionnaire. Mean Body Mass Index(BMI) was within the normal range, while 21% and 14% of the patients were underweight and overweight, respectively. They received nutrition information mainly from doctors, nurses and mass media, but rarely from nutrition professionals. A quarter of patients skipped breakfast at least 3 times per 12% of the patients, respectively. Energy intake of 83% of the patients was less than the recommended level. Protein intakes of 56% of them were either under or over the recommended levels. Patients had low vitamin B$_2$ and calcium(<75% of the RDA) and excessive phosphorus(138% RDA) and vitamin C(170% RDA). Major food sources to absolute nutrient intakes were similar to those for the average Koreas, except for milk. Milk intake was low in our patients. Dietary quantity and quality were associated positively with BMI, albumin, and HDL-cholesterol and negatively with triglycerides and BUN. Results of this study indicate low nutritional status of the patients and, in turn a need for conducting nutritional education or counselling at regular at regular basis for the nephritic patients with mild kidney malfunction.