• The Journal of the Acoustical Society of Korea
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• v.23 no.6
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• pp.446-453
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• 2004

In this paper, a new adaptive perceptual filter using variable threshold to enhance audio signals degraded by additively nonstationary noise is proposed. The adaptive perceptual filter updates variable threshold each time according to the power of signal and the effect of noise variation. So the noisy audio signal is enhanced by the method which controls a residual noise effectively. The proposed algorithm uses the perceptual filter which transforms a time domain signal into frequency domain and calculates an intensity energy and an excitation energy in bark domain. In this method. the stage updated the response of filter is decided by threshold. The proposed algorithm using vairable threshold effectively controls a residual noise using the energy difference of audio signals degraded by the additive nonstationary noise. The proposed method is tested with the noisy audio signals degraded by nonstationary noise at various signal -to-noise ratios (SNR). We carry out NMR and MOS test when the input SNR is 15dB. 20dB. 25dB and 30dB. An approximate improvement of 17.4dB. 15.3dB, 12.8dB. 9.8dB in NMR and enhancement of 2.9, 2.5, 2.3, 1.7 in MOS test is achieved with the input signals. respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.8
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• pp.759-769
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• 2013

Electronic equipment has been applied to virtually every area associated with commercial, industrial, and military applications. Specifically, electronics have been incorporated into avionics components installed in aircraft. This equipment is exposed to dynamic loads such as vibration, shock, and acceleration. Especially, avionics components installed in a helicopter are subjected to simultaneous sine and random base excitations. These are denoted as sine on random vibrations according to MIL-STD-810F, Method 514.5. In the past, isolators have been applied to avionics components to reduce vibration and shock. However, an isolator applied to an avionics component installed in a helicopter can amplify the vibration magnitude, and damage the chassis, circuit card assembly, and the isolator itself via resonance at low-frequency sinusoidal vibrations. The objective of this study is to investigate the dynamic characteristics of an avionics component installed in a helicopter and the structural dynamic modification of its tray plate without an isolator using both a finite element analysis and experiments. The structure is optimized by dynamic loads that are selected by comparing the vibration, shock, and acceleration loads using vibration and shock response spectra. A finite element model(FEM) was constructed using a simplified geometry and valid element types that reflect the dynamic characteristics. The FEM was verified by an experimental modal analysis. Design parameters were extracted and selected to modify the structural dynamics using topology optimization, and design of experiments(DOE). A prototype of a modified model was constructed and its feasibility was evaluated using an FEM and a performance test.

• Journal of Korean Public Health Nursing
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• v.3 no.2
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• pp.77-108
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• 1989

The purpose of this study was to find out the present condition of clinical practice and to develop a scheme on the efficiency of clinical practice for nursing education in junior college of nursing in korea. This study was conducted by 2 sections. Ist section was to find out the present condition of clinical practice to 42 directors of nursing collegd and data were collected July 8 to September 30, 1988. 2nd section wat to develop a scheme on the efficiency of clinical practice for nursing education and subjects were nursing professors 258: and clinical nurses 223 in 42 junior nursing colleges their clinical settings in korea. So total subjects were 481. Data were collected july 8, 1988 to June 30, 1988 and were analysed to get the mean, standand deviation, frequency, percentage, t-test, x-test used by SPSS - pc. Major findings were as follows: 1. The present condition of clinical education in junior college of nursing in Korea. 1) 32 colleges (76.2%) were managed by a-yeas system. 2) 25 colleges (59.5%) were performed by individual practice for each subject. 3) 4 weeks interval between class education and clinical education was a major type among total colleges(36.6%, J5 colleges) 4) 30 colleges (71.4%) provided clinical education for all subjects that should be practiced. Nursing administration wes not practiced in 5 colleges (41.9%) among the remainder(12 colleges). The main cause that all practice subjects were not practiced was the lack or absence of suitable clinical settings(8 colleges. 66.7%) 5) 18 colleges (42.9%) responded that a clinical educator was, subject-charged professor. 6) 12 colleges (29.3%) responded that a clinical instructor was in charge of 6~10 students. 7) The evaluation ration ratio(professor to head nurse) by each evaluator was mostly 50% to 50 % and 60% to 40%, respectively 11 colleges(27.5%) The most common evaluation methods were evaluation by head nures, report, presence, conference (11 colleges, 27.5%) 8) The field carrier of professor was mostly 2 years (79 persons, 20.7%) and mean was 3.2 years. The education carrier of a professor was mostly over than 6 years (261 persons, 66.4%) and mean was 9.2 years. The charge hours per-week of a professor were mostly 16-18 hours (16 persons, 131.8%) 9) 34 colleges (82.9%) approved that clinical practice hour was class hour and 18 colleges (43.9 %) counted that 2 hours of clinical education equaled 1 hour of class education. 2. A study 'on the efficiency of clinical practice for nursing education. L) general characteristics of subjects were as follows: kung-sang province (145 persons, 30.5%), 30-34 years (190 persons, 39.8%), graduated degree (245 persons, 51.5%), 6-10 years of carrier (199 persons, 41.4%) were the majority. 2) suitable clinical setting was responded the systematic ward with responsible clinical educator by 210 persons(43.8%) The response by working field of subjects showed a significant difference (p< 0.01) 3) 259 subjects (54.0%) responded that the desirable qualfication of clinical instructor was 3-5 years of clinical experience with master degree or higher. 4) The mean score of desirable quality degree of clinical instructor was 3.43 professors, score (3.54) was significantly higher than clinical nurses' (3.28) (p<0.01) 412 subjects (86.0%) responded that the insufficient guality of instructor was improved by continuing to seek more new information in reference. 5) 196 subjects (41.4%) responded that desirable qualification of head nurse was more than 2 years of head position among 5 years of clinical experience. The response by working' field of subjects showed a significant difference (p<0.05) 6) The mean score of desirable quality degree of head nurse was 3.18 Clinical nurses' score(3.38) was significantly higher than professors' (3.01) (p<0.01) 419 subjects (87.8%) responded that the insufficient of head nurse was improved by continuing relationship with instructor and being responsible from planing of clinical education. 7) The mean score of performance level of the desirable clinical education guide incollege was 2.91 Professors' score (2.96) was significantly higher than clinical nurses' (2.84) (p<0.01) 340 subjects (71.1%) responded that the possible resolution for poor performance was the more specified syllabus of clinical education and the satisfiable orientation for students. 8) The mean score of performance level of the desirable clinical education guide in hospital was 3.03 9) 141 subjects (29.6%) responded that the desirable clinical evaluator was the group of professor, head nurse, staff nurse. Response by working field of subjects was a significant difference (p< 0.05) 10) The mean score of performance level of the evaluation content needed in clinical education was 3.50 Clinical nurses' score (3.56) was significantly higher than professors' (3.45) (p<0.01) 11) 433 subjects (90.2%) responded that6 desirable evaluation method for clinical education was the presence. 12) The mean score of performance level about how personal difference among clinical educators was minimized was 2.89 and response by working field of subjects was not significant. The cause of poor performance was too much workload at clinical settings and too many students st colleges by 386 subjects (81.1%).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.196-213
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• 2001

A split beam ultrasonic transducer operating at a frequency of 70 kHz to use in the fish sizing echo sounder was developed and the acoustic radiation characteristics were experimentally analyzed. The amplitude shading method utilizing the properties of the Chebyshev polynomials was used to obtain side lobe levels below -20 dB and to optimize the relationship between main beam width and side lobe level of the transducer, and the amplitude shading coefficient to each of the elements was achieved by changing the amplitude contribution of elements with 4 weighting transformers embodied in the planar array transducer assembly. The planar array split beam transducer assembly was composed of 36 piezoelectric ceramics (NEPEC N-21, Tokin) of rod type of 10 mm in diameter and 18.7 mm in length of 70 kHz arranged in the rectangular configuration, and the 4 electrical inputs were supplied to the beamformer. A series of impedance measurements were conducted to check the uniformity of the individual quadrants, and also in the configurations of reception and transmission, resonant frequency, and the transmitting and receiving characteristics were measured in the water tank and analyzed, respectively. The results obtained are summarized as follows : 1. Average resonant and antiresonant frequencies of electrical impedance for four quadrants of the split beam transducer in water were 69.8 kHz and 83.0 kHz, respectively. Average electrical impedance for each individual transducer quadrant was 49.2$\Omega$ at resonant frequency and 704.7$\Omega$ at antiresonant frequency. 2. The resonance peak in the transmitting voltage response (TVR) for four quadrants of the split beam transducer was observed all at 70.0 kHz and the value of TVR was all about 165.5 dB re 1 $\mu$Pa/V at 1 m at 70.0 kHz with bandwidth of 10.0 kHz between -3 dB down points. The resonance peak in the receiving sensitivity (SRT) for four combined quadrants (quad LU+LL, quad RU+RL, quad LU+RU, quad LL+RL) of the split beam transducer was observed all at 75.0 kHz and the value of SRT was all about -177.7 dB re 1 V/$\mu$Pa at 75.0 kHz with bandwidth of 10.0 kHz between -3 dB down points. The sum beam transmitting voltage response and receiving senstivity was 175.0 dB re 1$\mu$Pa/V at 1 m at 75.0 kHz with bandwidth of 10.0 kHz, respectively. 3. The sum beam of split beam transducer was approximately circular with a half beam angle of $9.0^\circ$ at -3 dB points all in both axis of the horizontal plane and the vertical plane. The first measured side lobe levels for the sum beam of split beam transducer were -19.7 dB at $22^\circ$ and -19.4 dB at $-26^\circ$ in the horizontal plane, respectively and -20.1 dB at $22^\circ$ and -22.0 dB at $-26^\circ$ in the vertical plane, respectively. 4. The developed split beam transducer was tested to estimate the angular position of the target in the beam through split beam phase measurements, and the beam pattern loss for target strength corrections was measured and analyzed.

• The Journal of Korean Society for School & Community Health Education
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• v.9 no.1
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• pp.85-97
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• 2008

Objectives: This study was designed to understand the oral health knowledge & conduct of middle-school students, search for the learning objective and the educational method in line with the subjects and of utilizing as the basic data for an effective oral health-care program. Methods: The samples to achieve the purpose of this research are composed of 139 students in middle-school, OO county. Chungcheongbuk-do, the number of male students 64, and female students 75. Data were statistically analyzed by frequency analysis, $x^2$-test or Fisher's exact test by using SPSS WIN Ver. 12.0. Results: Among items on oral-health knowledge in middle-school students. the awareness ratio on a cause and preventive method for oral disease was surveyed to be lower than the awareness ratio on symptoms of oral disease. As a result of examining by comparing knowledge and behavior on the time of tooth brush. both awareness and behavior were the level of 50% or less than it. In particular, 46.2% perceived after lunch. but practice just accounted for 33.0%. The frequency of tooth brush a day was the largest in a case(47.5%) of doing twice a day. However. there was also the response (5.8%) with saying of brushing once or not brushing even once. Thus, the practice of tooth brush was surveyed to be very low even if being a minority of students. The frequency of taking a light meal was 68.8% in less than twice a day. However, even students of taking more than five times were surveyed to be 9.8%. Out of the whole-body health in over 50%-59.9%. the oral health was surveyed to be perceived to be very important. Compared to the awareness level on importance of a tooth, the ratio of visiting a dentistry was analyzed to be very low. Conclusions: The study results suggest that the school oral-health project was examined to have the necessity of being expanded and carried out even in middle-and-high schools, by which the specific oral-health promotion program including oral-health education in this period is developed.

• Journal of Korean Library and Information Science Society
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• v.9
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• pp.241-266
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• 1982

This paper gives a summary and overview of a survey conducted at the catalogues of five universities in Daegu during November 1982. The major objective of this study was to secure information about user needs in order to improve the catalogue in Korean university libraries. Data was collected by a combined method of questionnaire and interview. A total of 379 respondents were taken on a randomly selected sample of catalogue users. Results of the survey can be summarized as follows: 1. Eighty-eight percent of the students answered that they had used the library more than twice a month. Nevertheless the number of students consulting the catalogue with the same frequency was only 220, or a n.0, pproximately 58 percent. Those who used the library most tended to use the catalogue more than those who rarely came to the library. 2. Those who had been shown how to use their own catalogue were only 32.5percent of which the students found the instruction sufficient for them to be able to use the catalogue were only 37.5 percent. In particular, they stated that instructions by printed materials and/or library orientation were so poor that they didn't give much help in using the catalogue. This problem makes many libraries to review their own method of instruction in order to encourage patrons to use the catalogue more effectively. 3. Most of the students consulted the catalogue in order to locate library materials. Known-item searches and subject searches were 84 and 16 percent respectively. While 70.5 percent of the students used the author-title catalogue without any difficulties, only 35.5 percent of those stated that using the classed catalogue was easy. 4. It was surprising that the number of students using title access in the search was far greater than that of students using author access. In contrast with this, other studies conducted by many earlier overseas investigators revealed that the great majority of patrons tended to use the latter first. Therefore, we should put more emphasis on the title entries in the catalogue itself as well as cataloging rules. 5. Most useful bibliographic elements in the entry were author, title, call number, date and publisher whereas edition, series statement and the location of publisher were rarely used compared with the other elements. Content note was the most desirable element in the entry to be involved, for many catalogers were used not to describe it on the note area. 6. The chief reason given for not using the catalogue was "I can manage without it" with "It's difficult to understand contents of the card entry." The other one was "It's useless to search materials by the catalogue because I've failed so many times to obtain them out of the stock." In response to this, circulation and acquisition system should be improved not to make such complaints any more.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.2
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• pp.293-303
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• 2002

Recently, the use of the high strength materials and development of construction techniques have resulted in more flexible and longer spanning in the stadium systems. So the natural frequency of stadium structures are became low. Stadium stand could be led to significant dynamic response as like resonance due to spectator rhythmical activities. The accurate analysis of dynamic behavior of stadium systems and the precise investigation of the dynamic loads on stadium structures are demanded for effective design. It is desirable to apply measured dynamic loads created by spectator activities because these dynamic loads are not easy to express numerical formula. As the floor mesh of stadium stand is refined, the number of divided elements increases in numerical analysis. the rise of the number of elements makes the numbers of nodal points increased and numerous computer memory required. So it is difficult to analysis refine full model of stadium structures by using the commercial programs. In this study, the various dynamic loads induced by spectator movements are measured and analyzed. And a new modeling method that reduce the nodal points are introduced. Vibration analysis of stadium stands is executed to inspect accuracy and efficiency of proposed method in this paper.

• Journal of the Korean Society of Food Culture
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• v.5 no.3
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• pp.331-347
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• 1990

This study was designed under the purpose to analyze the Korean Traditional Folk Remedies on food, to submit the basic statistical data, and to utilize them by examining how much they know about the Korean Traditional Folk Remedies and also by examining how frequently they used them. The sample was consisted of 312 housewives living in Daegu, Kyungsan city and Kyungsan-eup, the survey was made by use of questionaires from July 15 to August 1 1989. The results are as follows 1. Analysis of Folk Remedical Contents 1) The method of the Folk Remedies used in this area was mainly food, which can be easily found around their house and easy to use, it was possible to apply scientific principles in some cases. 2) The major popular method was shown to feed boiled barley or brown rice which are known as the Folk Remedy for Diabetes. 3) The ANOVA of variable shows the significant influence on each object which age, religion, the level of education, job, monthly income, and the area except family formation. 2. The Frequency of Folk Remedies and additional analysis 1) The most frequently used Folk Remedy was Arterio-sclerosis(1.44), which is followed by the loss of Eyesight(1.40), Hang over(1.28), Couth(1.27), Cold(1.26) etc. 2) In the analysis of Pearson Correlation between frequencies of Folk Remedies used, and demographic variables such as age(p<.05), the monthly income(p<.01), in that area, total number of response items showed a positive correlation. 3. The source to learn about Folk Remedy. 1) It is acknoledged that they are mostly instructed by their forefathers, friends, neighbors, professional textbooks, mass communications, herb doctors, other medical sources or education at school etc. 2) The ANOVA of Variables shows the big differences between each group by age. Based on the above findings, the following suggestions are made ; Most of Korean Traditional Folk Remedies are recognized scientific and reasonable which are based on the scientific research and herb medicine therefore it should be made good use of for our life in good health additionally. I hereby insist that the importance of our Folk Remedies should be reviewed and focused for maintenance our health.

• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.69-86
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• 2022

The railway is widely used to transport passengers and freight due to its punctuality and large transport capacity. The recent remarkable development in construction technology enables various subsea railway tunnels for continent-continent or continent-island connectivity. In Korea, design and construction experience is primarily based on the successful completion of the Boryeong subsea tunnel (2021) and the Gadeok subsea tunnel (2010). However, frequent earthquakes with diverse magnitudes, globally induced and continuously increased the awareness of seismic risks and the frequency of domestic earthquakes. The effect of an earthquake on the subsea tunnel is very complicated. However, ground conditions and seismic waves are considered the main factors. This study simulated four ground types of 3-dimensional numerical models, such as soil, rock, composite, and fractured zone, to analyze the effect of ground type and seismic wave. A virtual subsea railway shield tunnel considering external water pressure was modeled. Further, three different seismic waves with long-term, short-term, and both periods were studied. The dynamic analyses by finite difference method were performed to investigate the displacement and stress characteristics. Consequently, the long-term period wave exhibited a predominant lateral displacement response in soil and the short-term period wave in rock. The artificial wave, which had both periodic characteristics, demonstrated predominant in the fractured zone. The effect of an earthquake is more noticeable in the stress of the tunnel segment than in displacement because of confining effect of ground and structural elements in the shield tunnel. 

• Journal of The Korean Dental Society of Anesthesiology
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• v.14 no.1
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• pp.17-27
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• 2014

Background: Various medical emergency situations can occur during dental practices. Cardiac arrest is known to comprise approximately 1% of emergency situation. Thus, it is necessary for dentists to be able to perform cardiopulmonary resuscitation (CPR) to increase the chance of saving patient's life in emergency situation. In this paper, we conducted a survey study to evaluate to what extent dentists actually understood CPR practice and if they had experience in handling emergency situations in practice. Method: The survey was done for members of the Korean Dental Society of Anesthesiology (KDSA), who had great interest in CPR and for whom survey-by-mail was convenient. We had selected 472 members of the KDSA with a dental license and whose office address and contact information were appropriate, and sent them a survey questionnaire by mail asking about the degree of their CPR understanding and if they had experience of handling emergency questions before. Statistical analyses -frequency analysis, chi-square test, ANOVA, and so on- were performed by use of IBM SPSS Statistics 19 for each question. Result: Among 472 people, 181 responded (38.4% response rate). Among the respondents were 134 male and 47 female dentists. Their average age was $40.4{\pm}8.4$. In terms of practice type, there were 123 private practitioners (68.0%), 20 professors (11.0%), 16 dentists-in-service (8.8%), 13 residents (specialist training) (7.2%) and 9 military doctors (5%). There were 125 dentists (69.1%) who were specialists or receiving training to be specialist, most of whom were oral surgeon (57, 31.5%) and pediatric dentists (56, 30.9%). There were 153 people (85.0%) who received CPR training before, and 65 of them (35.9%) were receiving regular training. When asked about the ratio of chest pressure vs mouth-to-mouth respiration when conducting CPR, 107 people (59.1%) answered 30:2. However, only 27.1% of them answered correctly for a question regarding CPR stages, C(Circulation)- A(Airway)- B(Breathing)- D(Defibrillation), which was defined in revised 2010 CPR practice guideline. Dentists who had experience of handling emergency situations in their practice were 119 (65.6%). The kinds of emergency situations they experienced were syncope (68, 37.6%), allergic reactions to local anesthetic (44, 24.3%), hyperventilation (43, 23.8%), seizure (25, 13.8%), hypoglycemia (15, 8.3%), breathing difficulty (14, 7.8%), cardiac arrest (11, 6.1%), airway obstruction (6, 3.3%), intake of foreign material and angina pectoris (4, 2.2%), in order of frequency. Most respondents answered that they handled the situation appropriately under the given emergency situation. In terms of emergency equipment they had blood pressure device (70.2%), pulse oximetry (69.6%), Bag-Valve-Mask (56.9%), emergency medicine (41.4%), intubation kit (29.8%), automated external defibrillator (23.2%), suction kit (19.3%) and 12 people (6.6%) did not have any equipment. In terms of confidence in handling emergency situation, with 1-10 point scale, their response was $4.86{\pm}2.41$ points. The average point of those who received regular training was $5.92{\pm}2.20$, while those who did not was $4.29{\pm}2.29$ points (P<0.001) Conclusion: The result showed they had good knowledge of CPR but the information they had was not up-to-date. Also, they were frequently exposed to the risk of emergency situation during their dental practice but the level of confidence in handling the emergency situation was intermediate. Therefore, regular training of CPR to prepare them for handling emergency situation is deemed necessary.