• Current Photovoltaic Research
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• v.6 no.3
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• pp.69-73
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• 2018

PV system is consisted with PV module, inverter and BOS(balance of system). To have robustic operation more than 20 years, the expected and guaranteed durability and reliability of products should be met. Almost components of PV system are qualified through IEC standards at test laboratory. But the qualification certificate of product does not ensure long-term nondefective operation. PV module's expected life time is nowadays more than 20 years and annual maximum power degradation ratio would be less than -1%. But the power degradation ratio is basically based on real data more than several years' record. Developing test method for ensuring annual maximum power degradation ratio is very need because there are many new products every month with new materials. In this paper, we have suggested new test method under continuous artificial light irradiation test condition for analyze expected maximum power drop ratio.

• Journal of the Korean GEO-environmental Society
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• v.20 no.9
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• pp.13-19
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• 2019

Dynamic earth pressure is considered an important parameter in the design of embedded structures. In current engineering design simplified methods developed either for yielding or non-yielding structures are utilized to predict resultant dynamic pressure. The applicability of these equations to embedded structures have not yet been reported. In this study we perform a suite of equivalent linear time history analysis for a range of embedded structure configurations. Numerically calculated dynamic pressure is shown to depend on the flexibility ratio (F), aspect ratio (L/H) of the embedded structure, and ground motion. Increase in L/H and intensity increases the magnitude of dynamic pressure. An increase in F decreases the dynamic pressure. Overall, the trends highlight the need for development of new method that accounts for F and L/H to calculate the dynamic pressure for the performance-based design of embedded structures.

• School Mathematics
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• v.4 no.4
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• pp.633-642
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• 2002

This paper focuses on the concepts of a value of ratio and a rate in elementary school mathematics. Although the concept of a value of ratio can be distinguished meaningfully from that of a rate by phenomenological analyses, this distinction is impossible at the elementary school level. Two concepts tend to be treated as identical, therefore they need to be classified by the other methods. By analyzing the series of mathematics textbooks from the first curriculum to the present 7th curriculum, this paper investigated how two concepts have been transposed into the products of school mathematics. In addition, we discussed how the difference of two concepts in the changing process of definitions have been presented clearly to the students. As a result, this paper concluded that the difference of two concepts has not been developed clearly for elementary students in general, except the textbook by the 7th curriculum. The definitions of two concepts were described obscurely so that the students may confuse the concept of a value of ratio with that of a rate. The role of a value of ratio needs to be reconsidered when it is applied to set proportional expressions. Therefore, this paper suggests not adhering to the terminology ‘value of ratio’ to present the ratio as a quotient or the rate as a fractional representation in school mathematics.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.3
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• pp.105-119
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• 2020

The purpose of this study is to analyze the hydrologic cycle environment of Gyeongui Line Forest Park, a linear city park, in order to improve hydrologic cycle systems in urban areas. The method of the study is the Biotope Area Ratio and the Permeable ratio survey. The study subject is the Gyeongui Line Forest Park, created in 2016 as a linear park in Seoul. The results showed that the Biotope Area Ratio improved by 31.2% (31,927㎡) from 35.7% (36,480㎡) in 2000 to 66.9% (68,407㎡) in 2019 on a site area of 102,117㎡. Next, the Permeable ratio improved by 43.8% from 29.0% to 72.8%, and the impermeable ratio decreased by 43.8% from 71.0% to 27.2%. The Biotope Area Ratio exceeded the target ratio of 60% by 6.9%, set by the Ministry of Environment. The ratio of green space exceeded the target ratio of 60%, by 4.0%. And so they contributed to the improvement of the hydrologic cycle by the creation of the Gyeongui Line Forest Park. Urban parks need to exceed the Biotope Area Ratio and the green area ratio of the legal standards, especially when creating large parks of over 100,000 square meters, in the era of climate change. It is necessary to continuously plant trees in the space where trees can be planted, and to contribute to the improvement of the hydrologic cycle system and urban heat island effect by conducting three-dimensional.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.154-162
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• 2020

We studies show that ratio of corpse among cremated bodies in public cremation facilities in metropolitan cities using E-Haneul funeral information system is average 90.1%, which is high, in bigger metropolitan cities with over 2 million of population (Incheon, Busan, and Daegu), but is average 81.4%, which is relatively low, in smaller metropolitan cities with less than 2 million of population(Daejeon, Gwangju, and Ulsan). In addition, the cremated bodies ratio of opening remains is average 17.4% in smaller metropolitan cities with less than 2 million of population, but is average 8.9% in those with over 2 million of population, which is relatively low. Finally, the cremated bodies ratio of dead fetuses is average 1.2% in smaller metropolitan cities with less than 2 million of population, and average 1.0% in those with over 2 million of population, which is low. Based on the above result, we are the following suggestions to improve the effectiveness of funeral facility use by the increase of demand for public cremation facilities in metropolitan cities. First, Busan and Daegu, where the shortage of supply is expected due to the increase of demand for cremation of corpse, need to implement supply expansion policy of public cremation facilities to build or expand cremation furnaces. Second, Daejeon, Gwangju, and Ulsan, where the cremated bodies ratio of corpse is low, need to expand supply through expanded operation from existing 4~8 cremation numbers of public cremation facilities to 11 cremation numbers, which is the level of Seoul Metropolitan City. Third, there should be cremation furnaces exclusively for opening remains to prepare the increase of demand for opening remains in the years with leap month.

• Journal of Pharmaceutical Investigation
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• v.6 no.3
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• pp.48-57
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• 1976

An enhancement in the dissolution rate of the drug should facilitate its GI absorption if the absorption process is dissolution rate limited. One of the need for the techniques that can potentially enhance the dissolution rate and extent of absorption of hydrophobic drugs is the formation of coprecipitates with pharmacologically inert, polymeric materials. The physicochemical modification offers the advantage of possibly enabling one to administer the drug orally in a form from which it is most available for GI absorption. Several $investigation^{1-15)}$ demonstrated that the formation of solid dispersions or coprecipitates of relatively water-insoluble drugs with various pharmacologically inert carriers can increase singnificantly their in vitro dissolution rates. However, little information is available in the literature related to the dissolution rate patterns of furosemide, a water-insoluble diurectices, with respect to the sort of copolymer and the ratio of coprecipitates as a function of time, respectively. The purpose of the present investigation was to ascertain, the general applicability of the copolymers to use fore more fast, enhanced dissolution techniques of furosemide. To accomplish the need for enhancement in the dissolution rate of furosemide, varying ratio coprecipitates with different water-soluble polymers, such as polyvinylpyrrolidone (PVP), polyethylene glycol 4000(PEG 4000), and polyethylene glycol 6000 (PEG 6000), were quantitatively studied by comparing their dissolution characteristics of furosemide. The dissolution patterns of pure furosemide, varying ratio furosemide-PVP coprecipitates, (1:2, 1:5, and 1:9(w/w)), furosemide-PEG 4000 coprecipitates (1:4, 1:9, and 1:19(w/w), furosemide-PEG 6000 coprecipitates(1:4, 1:9, and 1:19(w/w)), and the same ratio physical mixtures, respectively, were compared by the amount dissolved as a function of time.

• KIEAE Journal
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• v.10 no.6
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• pp.91-96
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• 2010

The problem of urban climate change and destruction of wildlife habitats space which is becoming more serious day by day, has to do with the impervious area(surface area) in urban space. The destruction of natural ground and indiscreet soil covering due to compact development is causing urban desertification in urban residential areas. With biotops area ratio being variously used and extended as a pre planning index, this study aims to analyze the elements of biotop area ratio that need to be supplemented in order to emerge as a realistic planning index for post evaluation measure and not act only as a examining tool in the planning stage. In particular, this study aims to examine the possibility of biotops area ratio to be used as a system to evaluate the outer space of apartment housings, in which biotops area ratio is most actively used, as a tool to secure ecological soundness of the development area after construction is finished.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.657-668
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• 2021

In this study, a relationship between the resonance frequency ratio and Poisson's ratio was proposed that can be used to directly determine the elastic constants. Using this relationship, the frequency ratio between the 1st bending mode and 2nd bending mode for any rectangular Timoshenko beam can be directly estimated and used to determine the elastic constants efficiently. The exact solution of the Timoshenko beam vibration frequency equation under free-free boundary conditions was determined with an accurate shear shape factor. The highest percent difference for the frequency ratio between the theoretical values and the estimated values for all the beam dimensions studied was less than 0.02%. The proposed equations were used to obtain the elastic constants of beams with different material properties and dimensions using the first two measured transverse bending frequencies. Results show that using the equations proposed in this study, the Young's modulus and Poisson's ratio of rectangular Timoshenko beams can be determined more efficiently and accurately than those obtained from industry standards such as ASTM E1876-15 without the need to test the torsional vibration.

• Journal of Chest Surgery
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• v.31 no.5
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• pp.494-501
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• 1998

From May 1, 1993 to May 31 1995, the authers studied retrospectively 211 patients who underwent cardiovascular operation with cardiopulmonary bypass(CPB). Because we were interested in new development of ARF(prevalence, mortality rate, and main risk factors), we performed a multivariate statistical analysis about data of patients with preoperative serum creatinine values of less than 1.5 mg/dL. Normal renal function before operation(serum creatinine level less than 1.5 mg/dL) was registered in 198(74%) patients. Of these, 27(14%) patients showed postoperative renal complication, including 20(10%) patients classified as renal dysfunction(serum creatinine level between 1.5 and 2.5 mg/dL) and 7(4%) patients as acute renal failure(serum creatinine level higher than 2.5 mg/dL). The mortality rate was 5.8% in normal patients, 5% in patients with renal dysfunction, and 43% when acute renal failure developed(p=0.036). Indeed, the renal impairment proved to be an independent predictor of mortality(odd ratio 2.52∼11.25), along with cardiovascular(odd ratio 4.20) and respiratory(odd ratio 2.18) complications. Multivariate analysis identified the following variables as independent risk factors for postoperative renal impairment : advanced age(odd ratio 1), need for emergency operation(odd ratio 3.78), low-output syndrome(odd ratio 3.66), respiratory complication(odd ratio 1.30), need for deep hypothermic circulatory arrest(odd ratio 1.4). The 13 patients(7%) with preoperative renal failure showed a significantly higher morbidity and mortality rate than those without renal complications before operation. We concluded that the likelihood of severe renal complications is resonably low in the patients undergoing cardiac operation without preexisting renal dysfunction, but associated mortality remains high. A prominant role of hemodynamic factor in the development of postoperative acute renal failure must be recognized during preoperative, intraoperative, and postoperative periods.

• Journal of Korean Academy of Nursing
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• v.39 no.1
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• pp.95-106
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• 2009

Purpose: The purposes of this study were to explore the functional status of elderly residents and to analyze time use, and finally identify factors to predict nursing care needs in relation to functional status and health related variables. Methods: In this study a descriptive-correlational design was used. Functional status of participants was obtained through interviews, and nursing care time was examined using a 1 min time-motion study with a standardized instrument developed by Korea Long-Term Care Planning Committee (2005). Results: The mean total functional score was 65 (range 28-125) and mean total nursing care time was 144.15 min per day. There were significant positive relationships between total nursing care time, marital status, back pain, dementia, and vision impairment. Multiple regression analyses showed that a liner combination of number of illnesses, types of primary disease, ADL, IADL, cognitive function, nursing demand, and rehabilitation demand explained 42.8% of variance of total nursing time. ADL (${\beta}$=-.533) was the most significant predictor of nursing service need. Conclusion: Identifying factors that result in variations of service need has implications for adequate nursing service, estimation of optimum nurse to patient ratio, quality of care and patient safety.