• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.4
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• pp.169-174
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• 2007

The characteristics of nine existing condensation frictional pressure drop correlations for microfin tubes were evaluated with geometries, vapor quality, mass flux, and refrigerants. The $M\ddot{u}ller-Steinhagen$ and Heck [17] smooth tube frictional pressure drop correlation was utilized to evaluate the pressure drop penalty factor (PF). Except the Nozu et al. [2], the Kedzierski and Goncalves [3], the Choi et al. [10], and the Cavallini et al. [7], other pressure drop correlations did not consider the effect of tube geometry. The prediction values for R407C by pressure drop correlations show discrepancy with previous researcher's experimental trend. Additional efforts on the development of reliable condensation pressure drop correlation for microfin tubes are still required with the systematic investigation of various effects like geometries and working conditions.

• Hwankyungkyoyuk
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• v.13 no.1
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• pp.87-95
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• 2000

Despite the perceived significance of cross-cultural studies in environmental education, only few of this kind have been conducted in Korea because of several barriers such as additional communicative, fanancial and administrative efforts. This cross-cultural study was conducted to examine if there were any significant differences in environmental awareness and attitude toward current environmental issues. The results revealed that the American subjects appeared to be more concerned with environmental issues, have higher willingness to act, and have more internalized Locus of Control than the Korean subjects. Similar observations have been reported by Horsley's(1984) study that compared environmental attitudes among students from 10 different countries. This study, however, suggested possibility of alternative interpretations of the results from the perspective of social- and cultural pscyhology.

• Journal of Korean Foot and Ankle Society
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• v.25 no.1
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• pp.10-16
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• 2021

Evidence-based papers on the treatment of some chronic tendinopathy or ligament lesions using an injection in foot and ankle disorders have been reported, but there are few reports on the treatment of acute ankle ligament injury. On the other hand, some papers have reported a faster return to play for injection therapy that combines RICE (Rest, Icing, Compression, and Elevation) treatment and rehabilitation. Injection therapy can be used as an additional treatment for ankle ligament injury. Rather than having narrow-minded thinking about these treatments, it is important to make efforts to verify the safety and precautions of treatment and recognize them as a category of normal treatment. Continuous analysis and monitoring of these treatments can satisfy patients whose needs are changing rapidly.

• Explosives and Blasting
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• v.39 no.3
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• pp.35-43
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• 2021

Slope optimization aims to maximize the slope angle in an open pit mine, resulting in subsequent profits from additional ore extraction. The large open pit mines have adopted the advanced technologies to increase slope angle until they ensure the slope stability. This paper introduces a current stage of slope optimization efforts and best practices from the open pit mines.

• Korean Journal of Head & Neck Oncology
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• v.38 no.2
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• pp.1-5
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• 2022

Due to the low incidence and histologic diversity of salivary gland cancer, analyzing the incidence of salivary gland cancer is necessary to understand the macroscopic aspects. We intend to investigate the international trend of the reported incidence rate of salivary gland cancer. Using the Korea Central Cancer Registry data, the domestic change in the incidence rate was examined. As a result, a significant increasing trend was confirmed, consistent with the United States and Japan trends. The etiology of the change is unclear, and various factors that may influence the direction are reported. Additional research is needed to understand the pathophysiology of salivary gland cancer, and further efforts are required to understand salivary gland cancer.

• The Korean Journal of Zoology
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• v.26 no.4
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• pp.295-296
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• 1983

Further research needs in environmental carcinogenesis are much to be desired. Currently, the methodology for identification, quantitation, and assay of some environmental carcinogens is available, but there remains a pressing need for additional fundamental knowledge of the carcinogenic process at the molecular level. The best hope for the control of cancer lies in prevention and chemotherapy, and this in turn depends upon the generation of basic information not yet available. The history of medical science reveals that quantum advances in control and prevention of disease have been direct consequences of research applications derived from pools of existing knowledge. It is hoped that the major efforts on specific problems of eivironmental carcinogenesis and substantial support of research to obtain new knowledge will prove to be equally rewarding.

• Korean Journal of Plant Taxonomy
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• v.52 no.4
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• pp.214-218
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• 2022

Eleocharis R. Br. (Cyperaceae) is characterized by unbranched culms, one terminal spikelet, bisexual flowers, and bristly perianths, occurring mainly in circumboreal marshes and wetlands. There are about 250 species worldwide, and 15 taxa in Korea have been recognized. Chromosomes in Cyperaceae are known to be holocentric, missing constricted centromeres during cell division. For the first time, we report the chromosome counts of Eleocharis from Korean populations of E. attenuata f. laeviseta (Nakai) H. Hara (2n = 20); E. parvula (Roem. & Schult.) Link ex Bluff, Nees & Schauer (2n = 10); E. ussuriensis Zinserl. (2n = 16); and E. valleculosa var. setosa Ohwi (2n = 16). The populations exhibit variations in their chromosome sizes from ca.1.7 ㎛ to ca. 6 ㎛, categorized as gradient and bimodal karyotypes. The karyotypes observed are congruent with previous phylogenetic groups proposed. To clarify the traditional and phylogenetic classification of Korean Eleocharis, further taxonomic and chromosomal investigations with additional taxon sampling efforts are required.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1555-1562
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• 2023

Natural circulation phenomena have been nowadays largely revisited aiming to investigate the performances of passive safety systems in carrying-out heat removal under accidental conditions. For this purpose, assessment studies using CFD (Computational Fluid Dynamics) and also 3D thermal-hydraulic system codes are considered at different levels of the design and safety demonstration issues. However, these tools have not being extensively validated for specific natural circulation flow regimes involving flow mixing, temperature stratification, flow recirculation and instabilities. In the present study, an experimental test case based on a small-scale pool test rig experiment performed by Korea Atomic Energy Research Institute, is considered for code-to-code and code-to-experimental data comparison. The test simulation is carried out using the FLUENT and the 3D thermal-hydraulic system CATHARE-2 codes. The objective is to evaluate and compare their prediction capabilities with respect to the test conditions of the experiment. It was observed that, notwithstanding their numerical and modelling differences, similar agreement results are obtained. Nevertheless, additional investigations efforts are still needed for a better representation of the considered phenomena.

• The Journal of Economics, Marketing and Management
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• v.5 no.4
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• pp.1-9
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• 2017

This current study aims to investigate the reason for the low birth rate and increasing aging populations. It aims to offer potential countermeasures and possible solutions that might alleviate the decreasing birth rate and exponentially increasing aging populations. The present research has sought out to uncover the origin of the low birth rates and increasing aging populations by compiling various past studies and statistics in South Korea. It includes additional support from the government for working career women in easing their burden for raising a child and allocating the appropriate funds for the increasing elderly populations. The decreasing birth rate can be contributed as a side effect of the past policies passed in South Korea and in turn created an increase in the aging populations. Policies to tackle this current issue needs to be further investigated and employed for the future of the economic and sociological stability of the society. Consistent efforts need to be made to dispel the continuing decrease for birth rates and alarmingly increasing aging populations. Policies and redistribution of government funds are some of the many things that need to be revised.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.4
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• pp.451-456
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• 2024

Organic photovoltaic (OPV) devices have attracted attention due to their high efficiency and simple manufacturing process. Applying an overlayer to OPV devices is one way to improve their performance because it can improve charge extraction and suppress vertical phase separation. In addition, dichloromethane (DCM) was used as an orthogonal solvent to minimize the effect on other layers. However, an coating problems due to the use of DCM were found, which affects surface morphology as rough or peeling. Additional research efforts are needed to solve these problems, and optimal results are expected to be obtained by utilizing various buffer layers or selective organic solvents.