• Geomechanics and Engineering
• /
• v.27 no.6
• /
• pp.561-571
• /
• 2021

Cofferdams made of teel sheet piles are commonly utilized as support structures for excavation of sea-crossing bridge foundations. As cofferdams are often subject to tide variation, it is imperative to consider potential effects of tide on stability and serviceability of sheet piles, particularly, ultralong steel sheet piles (USSPs). In this study, a real USSP cofferdam constructed using new construction technology in Nanxi River was reported. The design of key parts of USSP cofferdam in the presence of tidal action was first introduced followed by the description of entire construction technology and associated monitoring results. Subsequently, a three-dimensional finite-element model corresponding to all construction steps was established to back-analyze measured deflection of USSPs. Finally, a series of parametric studies was carried out to investigate effects of tide level, soil parameters, support stiffness and construction sequence on lateral deflection of USSPs. Monitoring results indicate that the maximum deflection during construction occurred near the riverbed. In addition, measured stress of USSPs showed that stability of USSP cofferdam strengthened as construction stages proceeded. Moreover, the numerical back-analysis demonstrated that the USSP cofferdam fulfilled the safety requirements for construction under tidal action. The maximum deflection of USSPs subject to high tide was only 13.57 mm at a depth of -4 m. Sensitivity analyses results showed that the design of USSP cofferdam system must be further improved for construction in cohesionless soils. Furthermore, the 5th strut level before concreting played an indispensable role in controlling lateral deflection of USSPs. It was also observed that pumping out water before concreting base slab could greatly simplify and benefit construction program. On the other hand, the simplification in construction procedures could induce seepage inside the cofferdam, which additionally increased the deflection of USSPs by 10 mm on average.

• Journal of the Korean Institute of Educational Facilities
• /
• v.8 no.3
• /
• pp.25-35
• /
• 2001

This study investigated technology education, laboratory management and facilities in middle schools with the goal of finding problems. Ninety-six randomly selected schools and questionnaire was done to the teachers of 84 schools which have laboratory. Five of these schools received on-site inspections. The results of study are as follows : 1) 12.5% of schools have no laboratory. The average laboratory has less than 50% of the necessary equipment for total operations. laboratories are used an average of once or twice per two time frame. 2) 80%of the laboratories are located at the end of a row of regular class rooms. The most common laboratory style is classroom plus hallway($90m^2$) style. 77% of laboratories have a single entrance. 3) 69% of teachers reported the worktable arrangement to be inconvenience. 68% of the schools have 9 worktables per laboratory. 38% say the worktables are not wide enough and 36% said they were appropriate. Table dimensions range from $95{\sim}110cm$ in width and from $210{\sim}225cm$ in length. 65% of the teachers say table height is low with a range from $76{\sim}82cm$. 86% of the teachers say that the height of chair is low and the range of its measurement is from $37{\sim}47cm$. 84% of the teachers points out that laboratory is poorly lighted.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.6
• /
• pp.1379-1397
• /
• 2013

We consider a system where a licensed radio spectrum is shared by multiple primary users(PUs) and secondary users(SUs). As the spectrum of interest is licensed to primary network, power and channel allocation must be carried out within the cognitive radio network so that no excessive interference is caused to PUs. For this system, we study the joint beamforming and power allocation problem via game theory in this paper. The problem is formulated as a non-cooperative beamforming and power allocation game, subject to the interference constraints of PUs as well as the peak transmission power constraints of SUs. We design a joint beamforming and power allocation algorithm for maximizing the total throughput of SUs, which is implemented by alternating iteration of minimum mean square error based decision feedback beamforming and a best response based iterative power allocation algorithm. Simulation results show that the algorithm has better performance than an existing algorithm and can converge to a locally optimal sum utility.

• Journal of Mechanical Science and Technology
• /
• v.20 no.10
• /
• pp.1702-1715
• /
• 2006

The increasing use of nano-positioners in a wide variety of laboratory and industrial applications has created a need for nano-mechatronics education in all engineering disciplines. The subject of nano-mechatronics is broad and interdisciplinary. This article focuses on the way nano-mechatronics is taught in department of mechanical engineering at Korea Advanced Institute of Science and Technology (KAIST). As one model of nano-positioning systems, design and experimental methodology is presented in this article. For design phase, the stiffness and resonant frequencies are found analytically and verified by using a commercial finite element analysis program. Next, for experimental phase, various tests are performed to access the performances of the designed nano-positioner, for example, sine-tracking, multi-step response and travel-range check etc. Finally, the definition of 'separation frequency' is described and some comments are discussed.

• Korean Journal of Clinical Laboratory Science
• /
• v.50 no.2
• /
• pp.164-169
• /
• 2018

The development of teaching models to strengthen practical education and actively participate in the classes of students is now required in recent education situations. This study examined the participation and satisfaction level of students' classes after applying a teaching model-integrated hospital and school laboratory (named L2L). A total of 33 students who took the subject of a clinical microbiology experiments were involved in this study. Each group representative participating in a pre-class field exercise in the hospital microbiology laboratory was asked to conduct the experiment. After applying the L2L teaching models, the academic self-efficacy ($2.87{\pm}0.58{\rightarrow}3.38{\pm}0.55$), class participation ($2.60{\pm}0.92{\rightarrow}3.62{\pm}0.78$), and class satisfaction ($2.48{\pm}1.01{\rightarrow}3.85{\pm}0.87$) increased significantly (P<0.05). This means that pre-class field exercises created interest in the student's class and boosted self-confidence, leading to increased participation and satisfaction for the class. In conclusion, the L2L teaching model is an effective teaching method to enhance the practical training for preliminary clinical laboratory technologists.

• Nuclear Engineering and Technology
• /
• v.53 no.11
• /
• pp.3685-3693
• /
• 2021

This paper presents a disturbance observer-based robust backstepping load-following control (DO-RBLFC) scheme for modular high-temperature gas-cooled reactors (MHTGRs) in the presence of actuator saturation and disturbances. Based on reactor kinetics and temperature reactivity feedback, the mathematical model of the MHTGR is first established. After that, a DO is constructed to estimate the unknown compound disturbances including model uncertainties, external disturbances, and unmeasured states. Besides, the actuator saturation is compensated by employing an auxiliary function in this paper. With the help of the DO, a robust load-following controller is developed via the backstepping technique to improve the load-following performance of the MHTGR subject to disturbances. At last, simulation and comparison results verify that the proposed DO-RBLFC scheme offers higher load-following accuracy, better disturbances rejection capability, and lower control rod speed than a PID controller, a conventional backstepping controller, and a disturbance observer-based adaptive sliding mode controller.

• Journal of Korean Home Economics Education Association
• /
• v.32 no.4
• /
• pp.53-65
• /
• 2020

This study aimed to suggest measures expand career-related elective subjects in the high schools through a case of establishing and utilizing a learning space for hands-on home economics classroom activities. Upon the trend reviews of elective subjects in the high school and literature reviews on the educational outcomes from home economics classrooms, a case of career-related elective subject by establishment of learning space related to home economics was proposed in two high schools in Seoul. The results are as follows: First, the trend in 2020 showed that selecting a home economics course as a career-related subject depends on school situations. The results of the survey at schools show that the utilization rate of hands-on learning space for home economics was high with high preference among students, but schools implicitly guided students to select courses that are related to preparation for university entrance. Second, reductions of class hours and decreased likelihood to offer courses in home economics in general high schools would influence the recruitment of teachers, which may ultimately result in a threat to the subject. However, through career-related activities, students may develop positive perception of the subject of home economics and consequently select the subject. Therefore, it is necessary to open and promote multiple elective courses related to home economics for the survival of subject of home economics.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.10
• /
• pp.3230-3255
• /
• 2022

Causality mining in NLP is a significant area of interest, which benefits in many daily life applications, including decision making, business risk management, question answering, future event prediction, scenario generation, and information retrieval. Mining those causalities was a challenging and open problem for the prior non-statistical and statistical techniques using web sources that required hand-crafted linguistics patterns for feature engineering, which were subject to domain knowledge and required much human effort. Those studies overlooked implicit, ambiguous, and heterogeneous causality and focused on explicit causality mining. In contrast to statistical and non-statistical approaches, we present Bidirectional Encoder Representations from Transformers (BERT) integrated with Multi-level Feature Networks (MFN) for causality recognition, called BERT+MFN for causality recognition in noisy and informal web datasets without human-designed features. In our model, MFN consists of a three-column knowledge-oriented network (TC-KN), bi-LSTM, and Relation Network (RN) that mine causality information at the segment level. BERT captures semantic features at the word level. We perform experiments on Alternative Lexicalization (AltLexes) datasets. The experimental outcomes show that our model outperforms baseline causality and text mining techniques.

• Journal of Technologic Dentistry
• /
• v.25 no.1
• /
• pp.203-218
• /
• 2003

The 3 year graduate school course of the dental technician, which has been enforced since 1994 till the present date, differs from the currently existing 2 year graduate course because of an 8 weeks clinical field training course being newly executed and an imposed curriculum about manufacturing specialized prosthetics like all-ceramic, double prosthetic technology, attachment, and implant. Even though nearly 10 years have passed, the education program of the 18 colleges have still not been standardized and the subjects differing a little, while some are still not following the 3 years graduate course. The goal of this research is to emphasize the qualities of the 3 years graduate program and enable the dental technician to handle clinical models in the dental technical clinic right after graduation by adding clinical field training in the dental technician education program of the 18 colleges. Also in accordance to a national and international increase in esthetical prosthetics, credits, weekly study hours, education practice time of specialized prosthetic dental technology can be analyzed as follows. 1. In the year 2003, currently colleges start clinical practice education starting from the 1st semester of the 2nd year junior year, to the 2nd semester of 3rd year the varying in time with adequate class time, and credits. The average credit is 9.56, and weekly average class time is 18.00 hours. later clinical trainee education will be adjusted to the 3 year graduate school course to 10 credits and 20 hours and the adequate education period should be the 2nd semester of 3rd grade when most basic clinical education has been covered. 2. Currently in the year 2003, all-ceramic education has an average credit of 8.01 in 17 colleges with an exception of Ma-san college. The weekly average theoretical education is 4.94 hours, weekly clinical education of 7.88 hours and currently in 14 colleges porcelain technical class usually starts in the 1st semester of the 2nd year. All-ceramic education is thought to have adequate credits, timing, and weekly study hours. 3. Currently in 2003 implant education is enforced in 11 colleges including Bu-san Catholic university and the education period is usually in the 3rd year. Out of the 11 colleges, only Bu-san Catholic univ., Ma-san and Shinheung college have practice training classes. We knew that Shingu, Dongu, Mokpo science colleges have practice training as a curriculum, namely specific prosthetics laboratory. Out of the 9 colleges enforcing implant education the average credits taken are 2.56, and the average hours of weekly theory education is 2.14, but with the exception of Shinheung college which has an implant practice training course theory and practice classes are not divided. Therefore implant education is thought to start in the 3rd year as a 3 credit course with 3 hours of theory and practice each. 4. Currently in 2003, theoretical attachment education is given in 15 colleges and including practical training it is given in 10 colleges. The education starts 1st semester of the 2nd year till the 2nd semester of the 3rd year. The average credit of attachment theory education in the 15 colleges was 3.64, the average weekly theoretical education was 2.64, and the average weekly practice training out of the schools teaching it was 3.20. Later attachment education is thought to start the 1st semester of the 3rd year as a 3 credit course with 2 hours of theory class and 3 hours of practice training. 5. Double prosthetic technology is currently carried out in Dae-jon Health Science college(2nd year 2nd semester, 2 credits, theory 2hours), Gimcheon college (1 credit, 2 hours of practical training), Bu-san Catholic university (4th year 2nd semester, 4 hours of theory. practice). When the 3 year course is enforced, education will start 1st semester of the 3rd year with 2hours of theory and practice each. 6. The newly installed programs of the 3 year education is clinical field training, and specialized prosthetic manufacturing practice like all-ceramic, double prosthetic technology, attachment, and implant. If such education is to be effectively managed, a primary precursor as systemic basic clinical education is thought to be important. 7. Nationally in the 18 colleges of dental technology the currently executed curriculum course had varying subjects, class time according to the subject, and credits by each college. The curriculum difference between the colleges must be settled.

• Journal of Technologic Dentistry
• /
• v.12 no.1
• /
• pp.73-93
• /
• 1990

The study objected to the 120 persons out of 360 persons who have registered under the association of the dental technicians in Pusan to grasp contents about improvement of life long education of the present day of November, 1987, and its results, which we have acquired by this study were as follows : 1. A sense of satisfaction toward the system of life long education appeared as unsatisfaction and its unsatisfaction decreased from the rate of member's attendance or exam. marks, the contents of education, and place of education. 2. The problem of the exam. mark which derived by the presence by the substitute appeared which 46.7 percent(56 persons), lack of opportunity for the recompletion at branch association appeared which 19.2%(23 persons), given 4. exam. marks at the over all scientific contest was appeared 14.2 percent(17 persons), relation which legal treatment when ones didn't completed exam. mark was appeared 10.8 percent(13 persons) and lastly, appeared 8.3 percent (10 persons) with time of delivery of the exam mark card. 3. The frequency of the opening for the life long education which related with the rate of members attendance was fixed as nowadays two times per annually, but they perferred the opening per academic blanch once out of the firest half year and the latter half of the year and, they liked the openings at the first week or second week and preferred the holding on saturdays and sundays. 4. The subject of the life long education have appeared the opinion that the thesis was lop-sided toward the allocation of time schedule of lecture appeared the opinion of which they perferred the rate of an hour of cultural subject and two hours of major studies, and invitation for an instructor they preferred one dentist, one member, one dean for the cultural subject, and there are lots of opinions which they wished display of materials. 5. A sence of satisfaction about the place they perferred was decreased such as ; an auditorium concerned of the colleges was 46.7 Percent(56 Persons), hotels 26.7 Percent(32 Persons), an auditorium of the general hospital 20 percent(24 persons) 6. And lastly, there are lots of opinions who have required the necessities to constitute for the academic branch.