• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.40-46
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• 2017

Shipping activities have become possible in the Arctic Ocean due to melting ice by global warming. An increasing number of vessels are passing through the Arctic Ocean consequently bringing concerns of ship-iceberg collisions. Thus, most classification societies have implemented regulations to determine requirements for ice strengthening in ship structures. This paper presents the simulation results of an ice-strengthened polar class ship after an iceberg collision. The ice-strengthened polar class ship was created in accordance with the Unified Requirements for a Polar-Ship (IACS URI). An elastic-perfect plastic ice model was adopted for this simulation with a spherical shape. A Tsai-Wu yield surface was also used for the ice model. Collision simulations were conducted under the commercial code LS-DYNA 971. Hull deformations on the ice-strengthened foreship structure and collision interaction forces have been analysed in this paper. A normal-strength ship structure in an iceberg collision was also simulated to present comparison results. Distinct differences in structural strength against ice impact forces were shown between the ice-strengthened and normal-strength ship structures in the simulation results. About 1.8 m depth of hull deformation was found on the normal ship, whereas 1.0 m depth of hull deformation was left on the ice-strengthened polar class ship.

• Journal of The Korean Association For Science Education
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• v.26 no.5
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• pp.660-673
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• 2006

There have been many attempts to determine the value and the role of school laboratory experiment, but it seems hard to find consensus among these attempts from the perspective of education. This difficulty seems mainly due to disagreement on the concept of education, which has caused an instrumental attitude considering the school laboratory only as a means of developing science or pursuing various functions of school. However, the Endogenous Theory of Education (ETE), which claims education as 'a form of life', has recently paved the way for laboratory experiment to be justified as an opportunity of 'educooperation' allowing students to experience the intrinsic values of education in the medium of science. According to this theory, it is not the detailed practicals but the whole context where the laboratory activity is situated that matters in revealing the inherent educational phenomena. Through this new perspective, I observed two biology laboratory classes in a high school and analyzed the pattern of teacher-student and student-student interactions. Some meaningful educooperation was found in students' chattering, which has been traditionally considered as merely noise in the classroom, rather than in teacher-student interactions. This study discusses the reasons for these findings in detail and culminates in suggesting ways for accentuating the educational aspect of school laboratory activity.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1251-1264
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• 2018

The systematic and effective design method of a Class-D current-source resonant inverter for use in an induction cooker with zero-ripple line current is presented. The design procedure is based on the principle of the Class-D current-source resonant inverter with a simplified load network model that is a parallel equivalent circuit. An induction load characterization is obtained from a large-signal excitation test-bench based on parallel load network, which is the key to an accurate design for the induction cooker system. Accordingly, the proposed scheme provides a systematic, precise, and feasible solution than the existing design method based on series-parallel load network under low-signal excitation. Moreover, a zero-ripple condition of utility-line input current is naturally preserved without any extra circuit or control. Meanwhile, a differential-mode input electromagnetic interference (EMI) filter can be eliminated, high power quality in utility-line can be obtained, and a standard-recovery diode of bridge-rectifier can be employed. The step-by-step design procedure explained with design example. The devices stress and power loss analysis of induction cooker with a parallel load network under large-signal excitation are described. A 2,500-W laboratory prototype was developed for $220-V_{rms}/50-Hz$ utility-line to verify the theoretical analysis. An efficiency of the prototype is 96% at full load.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.477-488
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• 2017

This study presents a discussion on the biomedical laboratory science (formally clinical laboratory science or medical laboratory science) with the identity of biomedical laboratory science, as well as the academic classification system for systematic approach. The field of biomedical laboratory science is not registered in the academic research area classification system of the National Research Foundation of Korea. Since the inception of the first department of biomedical laboratory science in 1963, about 52 departments were since established. Despite the scientific identity, biomedical laboratory science have not been acknowledged professionally in most institutions. Observing the academic research area classification, the physical therapy, occupational therapy, and dental hygiene science are systematically classified and approved the identities by the authorities. This study is freshly academic area classification system of the biomedical laboratory science. The contents of this study are summarized as follows. The medical laboratory technologist's discipline is considered within the medical and science category, clinical pathology in class, and biomedical laboratory science in division. Sections of biomedical laboratory science include hematology, transfusionology, immunology, biochemistry, microbiology, parasitology, science, molecular biology, histology, cytology, cardiopulmonary physiology, and neurophysiology.

• Molecules and Cells
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• v.19 no.2
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• pp.223-227
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• 2005

We have identified TMPRSS6, a novel type 2 transmembrane serine protease. TMPRSS6 possesses all the signature motifs of the family of transmembrane serine proteases (TMPRSSs), including a transmembrane domain, an LDL receptor class A (LDLRA) domain, a scavenger receptor cysteine-rich (SRCR) domain, and a serine protease domain. The substrate specificity of TMPRSS6 is slightly different from those of other TMPRSS family members. Combined with the finding that TMPRSS6 is expressed strongly in the thyroid and weakly in the trachea, this may indicate that TMPRSS6 has a specialized role.

• Journal of the Korean Mathematical Society
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• v.57 no.5
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• pp.1299-1322
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• 2020

We consider closed, star-shaped, admissible hypersurfaces in ℝⁿ⁺¹ expanding along the flow Ẋ = |X|^α-1 F^-β, α ≤ 1, β > 0, and prove that for the case α ≤ 1, β > 0, α + β ≤ 2, this evolution exists for all the time and the evolving hypersurfaces converge smoothly to a round sphere after rescaling. Besides, for the case α ≤ 1, α + β > 2, if furthermore the initial closed hypersurface is strictly convex, then the strict convexity is preserved during the evolution process and the flow blows up at finite time.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.878-883
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• 1990

There have been many approaches to solve the disturbance rejection problem in the control of LTI systems with state independent disturbances or possibly nonlinear state dependent disturbances. From the view point of each actuator, robot manipulators can be modeled as the second class of systems. With this model, M.Nakao et al. [1] introduced a decentralized control scheme based on interference estimation which is simple in its implementation and robust to the coupled dynamics and parameter variations. This paper systematically generalizes the control scheme to arbitrary finite dimensional LTI systems with disturbances. In doing so, we develop a disturbance observer theory for solving the disturbance rejection problem. We also present a discrete version of the theory with discussion of sampling and time-delay effects.

• Journal of Technologic Dentistry
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• v.37 no.3
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• pp.157-167
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• 2015

Purpose: This study studied and investigated the oral health behavior of students in the Department of Dental Technology at D College at D City. Methods: A self-administrated survey was conducted by students currently enrolled at the Department of Dental Laboratory Technology at D College (June 4, 2015 ~ June 12, 2015), and 320 copies that were available for statistical processing were statistically analyzed by using the SPSS 19.0 Program. Results: Among the survey respondents, 91.6% had experience of dental treatment. The highest response regarding the frequency of tooth brushing appeared to be 'twice' with 44.7%. The responses regarding the time of tooth brushing appeared to be highest for 'before sleeping' with 65.3%, which was followed by 'after breakfast' with 60.6%. To the question asking which areas are brushed during tooth brushing, the response of 'teeth, gum, and tongue' appeared to be highest with 44.4%. Among the respondents, 64.7% experienced scaling, however, the experience rate for scaling appeared to increase in proportion with the increase of class year (p< .001). Regarding the subjective feel for the importance of oral health and necessity of tooth brushing, the scores appeared to be both 4.56. However, the score appeared to be 3.27 regarding one's subjective perception of one's own oral health condition. Regarding one's subjective oral health knowledge level depending on gender, female students showed a meaningfully lower rate (3.12 points) compared to male students (3.29 points) (p< .05), and depending on class, the knowledge level appeared to be meaningfully higher along with the increase in class year (p< .001). The experience of receiving oral health education appeared to be 78.4%, and 88.8% of the respondents responded that there is need for oral health education, however, the intent to participate in an oral health education program appeared to be 56.6%. Conclusion: As a result of the study, it could be concluded that oral health management behaviors and awareness of the students at the Department of Dental Technology at D University to prevent oral diseases were rather poor.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.101-115
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• 2016

We carried out laboratory material tests on two cements (KS-1 ordinary Portland and Class G) with changing W/S (Water/Solid) and the content of fly ash in order to evaluate their physical and mechanical properties. The specimens of KS-1 ordinary Portland cement were prepared with varying W/S (Solid=cement) in weight, while those of Class G cement were prepared with changing the content of fly ash in volume but maintaining W/S (Solid=cement+fly ash). The results of the material tests show that as the W/S in KS-1 ordinary Portland cement and the content of fly ash in Class G cement increase, the properties (density, sonic wave velocity, elastic constants, compressive and tensile strengths, thermal conductivity) decrease, but porosity and specific heat increase. In addition, an increase in confining pressure and in the content of fly ash leads to plastic failure behavior of the cements. The laboratory data were then used in a stability analysis of cement sheath for which an analytical solution for computing the stress distribution induced around a cased, cemented well was employed. The analysis was carried out with varying the injection well parameters such as thickness of casing and cement, injection pressure, dip and dip direction of injection well, and depth of injection well. The analysis results show that cement sheath is stable in the cases of relatively lower injection pressures and inclined and horizontal wells. However, in the other cases, it is damaged by mainly tensile failure.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3309-3315
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• 2016

Helicobacter pylori as the second most common cause of gastric cancer in the world infects approximately half of the developed countries population and 80% of the population living in developing countries. Integrons as genetic reservoirs play major roles in dissemination of antimicrobial resistance genes. To the best of our knowledge, this is the first study to report carriage of class 1 and 2 integrons and associated gene cassettes in H. pylori isolates from Iran. This cross-sectional study was conducted in Tehran among 110 patients with H. pylori infection. Antimicrobial susceptibility testing (AST) for H. pylori strains were assessed by the micro broth dilution method. Class 1 and 2 integrons were detected using PCR. In order to determine gene cassettes, amplified fragments were subjected to DNA sequencing of both amplicon strands. The prevalence of resistance to clarithromycin, metronidazole, clarithromycin, tetracycline, amoxicillin, rifampin, and levofloxacin were 68.2% (n=75), 25.5% (n=28), 24.5% (n=27), 19.1% (n=21), 18.2% (n=20) and 16.4% (n=18), respectively. Frequency of multidrug resistance among H. pylori isolates was 12.7%. Class 2 integron was detected in 50 (45.5%) and class 1 integron in 10 (9.1%) H. pylori isolates. The most predominant gene cassette arrays in class 2 integron-bearing H. pylori were included sat-era-aadA1, dfrA1-sat2-aadA1, blaoxa2 and, aadB whereas common gene cassette arrays in class 1 integron were aadB-aadA1-cmlA6, aacA4, blaoxa2, and catB3. The high frequency of class 2 integron and multidrug resistance in the present study should be considered as a warning for clinicians that continuous surveillance is necessary to prevent the further spread of resistant isolates.