• 한국임상수의학회지
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• 제33권4호
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• pp.221-224
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• 2016

An 8 month-old male Maltese (weighing 2.0 kg) was referred with loud heart murmur at routine physical exam in local animal clinic. Electrocardiogram found left ventricular hypertrophy pattern (4.5 mV R-wave). Diagnostic imaging studies revealed the elongation of left ventricle (LV) with classic triple bumps on the main pulmonary artery, aorta and left atrium on the ventrodorsal view of radiograph. Echocardiography revealed patent ductus arteriosus (PDA) duct and continuous turbulent shunt flow (maximal velocity 4.83 m/s) between the aorta and pulmonary artery with left to right direction. The PDA in this dog was successfully closed through femoral vein (transvenous approach) using a 5 mm Amplatz$^{(R)}$ Canine Duct Occluder. To the best of author's knowledge, this is the first case of PDA occlusion treated with Amplatz Canine Duct Occluder through femoral vein.

• 천문학회보
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• 제39권2호
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• pp.68.2-68.2
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• 2014

High Frequency Peakers (HFPs) are radio-loud Active Galactic Nuclei (AGN), which are regarded as being in the earliest evolutionary phase (102-103 years) of radio galaxies. They are expected to be small in size (< ~1 kpc) compared to their host galaxies (~a few 10s kpc), and have convex spectra, which are peaking at high radio frequency (> 5 GHz). Their size and spectral shape are the most obvious supporting evidence of extremely young ages. HFPs are therefore ideal targets to probe the earliest stage of radio sources. To date however, the young radio source classification has been relying mainly on the spectral shape which usually does not cover high enough frequencies where the true peak flux is located. Hence HFPs are often confused with blazars which may show a similar spectral shape and apparent compactness but are a somewhat evolved form of AGNs. Therefore, we have been challenging to identify HFPs among the sample of 19 candidates using the Korean VLBI Network (KVN) which enables us to extend the radio spectrum baseline up to 22 and 43 GHz. These are higher than the frequencies used in most previous studies of HFPs, allowing us to select genuine HFPs. By long-term monitoring of 18 epochs, we have also inspected the variability of the sample to select out blazars which are highly variable yet with a similar radio spectrum. In this work, we present the light curves and spectral properties of the HFP candidates. We discuss the results of our re-identification of HFPs.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.483-486
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• 2006

The fan is widely used to cool high heat flux generated as of the electronic communication device consoles. It, however, makes a lot of noises that interfere considerably with the operation environment. This study was conducted to obtain the cooling design technology of the consoles through being equipped with the Heat Pipe Heat Exchangers (HPHE) together with low revolution fans in place of existing fans for the cooling technology of the forced convection. Not only the sealed type consoles but the HPHE were also designed so as to cool effectively the heat generated from the inside of the console. The simulation was conducted by computational numerical analysis along with its experiments. The results of the numerical analysis and experiments were compared in order to improve the cooling technology of the consoles mounted with the HPHE. Consequently, instead of loud fan noise generated as of existing forced convection methods, the cooling technology of HPHE can remarkably improve many problems such as the operation environment, indoor dust, malfunction caused by pollution sources and so on.

• 말소리와 음성과학
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• 제5권4호
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• pp.53-61
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• 2013

Voice disorders are most common in female teachers due to work-related vocal demands; however, only a few studies tried to evaluate individual risk factors with work-related risk factors to diagnose voice disorders. This study evaluated sixty-seven female elementary teachers (36 with voice disorders and 31 without voice disorders) to compare their vocal misuse, overuse, and vocal hygiene behaviors. Total Voice Handicap Index scores and VHI subscale (P, E, F) scores were not significantly different between two groups (p>0.05) and there was no relationship between VHI and acoustic measures (p>0.05). Loud talking, talking in noisy situations, and excessive speaking were significantly more frequent in female teachers with voice disorders (p<0.05) and thereby these overuse and misuse behavioral patterns were identified as risk factors to develop voice disorders in female teachers. Also, hydration was the most common behavior for vocal hygiene when experiencing vocal fatigue; however, hydration with hot green tea or coffee and throat clearing were often misused for vocal hygiene. This study found that female teachers from both groups presented higher voice handicap regardless of voice disorders. This study suggests a multidimensional voice assessment protocol is required to reflect voice problems in teachers and a vocal education program may be important to improve vocal hygiene knowledge and behavioral changes in female teachers.

• 대한치과기공학회지
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• 제36권2호
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• pp.111-118
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• 2014

Purpose: Production of dental prosthesis by a dental technician causes a loud noise. Thus, we investigated stress of dental technicians due to a noise using a structured questionnaire. Methods: A survey was conducted on working dental technicians across the country from July 2013 to November 2013; among 200 sets of survey distributed, 166 were completed and returned, and excluding the 11 that deemed unsuitable, 155 sets were used for statistics. The program SPSS 19.0 was used to analyze the correlation among the collected data. Results: The stress of noise was found to be 2.83/5 points (2.93/5 for physical stress, 2.72/5 for emotional stress). Recognition of noise was found to be 2.71/5 points (3.39/5 for recognition of noise, 2.64/5 for accidents caused by noise, 2.29/5 for experiencing disability due to noise). For general items, the highest stress were shown for the following catogories: by gender, females (p=.008); by position, chief engineer (p=.033); by monthly pay, 2.51M-3.0M KRW (p=.023); by interior comfort, 'very unpleasant' was the highest recognized (p=.014). For the effect of time exposed to noise, its stress (p=.000) and recognition (p=.000) rose with increase of time. Conclusion: Dental technicians performs tasks in work environments exposed to extreme noise. This research attempts to re-emphasize the necessity for improving the work environment for noise and provide measures of blocking noise and precaution.

• 한국소음진동공학회논문집
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• 제14권11호
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• pp.1066-1074
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• 2004

A vibration isolation system for a large reverberation chamber (1,228 $m^3$ and 1,000 ton) has been installed and verified. The reverberation chamber generates loud noise and induces high level of vibration while performing spacecraft acoustic reliability tests. The isolation system prevents vibration transfer from the chamber to the enclosure buildings. This paper describes design process and commissioning experiments of the system. Design criteria have been derived from rigid body model of the chamber. The stiffness of neoprene pads has been selected by employing finite element analysis of the reverberant chamber and isolation system. A total of 21 neoprene pads have been installed between the chamber and supporting Pedestals. A sand bag of 800kg was dropped on the chamber floor to measure the natural frequency of the isolation system. While 136.9 dB noise is generated in the chamber, absolute transmissibility of the isolation system has been measured. The measured natural frequency of the chamber is 10.2Hz, which is 80% of the predicted value. Overall transmissibility at working frequency range (25∼10.000 Hz) is less than -12.4 dB.

• 한국소음진동공학회논문집
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• 제22권5호
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• pp.429-436
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• 2012

In concert halls and auditoriums, acoustic reflector and stage enclosure is one of the main factors on the room and stage acoustic characteristics. As a stage enclosure and acoustic reflector honey comb based light-weight reflector is widely used, because it is easy to install. However, there was not enough research on the surface density effect on room and stage acoustics. In this study, sound absorption coefficient tests on three kinds of wooden acoustic reflectors with different surface density were conducted. Surface density of acoustic reflector was changed from 11 kg/$m^2$ to 41 kg/$m^2$. For the low frequency excitation, sub-woofer was used with omnidirectional loud-speaker simultaneously. From the experiments, it was found that sound absorption coefficient below 250 Hz band was decrease by the increment of surface density. In order to check the influence of the surface density on room and stage acoustic parameters, room acoustic simulation was conducted with sound absorption coefficients, which were tested in reverberation chamber. By the increment of surface density of acoustic reflector, RT(reverberation time) and EDT(early decay time) were increased. Also, ST(stage support) was improved in low frequency bands.

• 말소리와 음성과학
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• 제9권4호
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• pp.99-106
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• 2017

Clinical data about vocal nodules have seldom been reported, even though vocal nodules are commonly diagnosed in outpatient speech and voice clinic. This study aims to investigate clinical characteristics of the patients who are diagnosed with vocal nodules. This study analyzed the data for 10 years from the 319 patients diagnosed with vocal nodules (45 males and 274 females with the mean age of 39.4 ranging from 2 to 83) in terms of gender, age, occupation, voice change initiation pattern, change with time, throat clearing, smoking history, type of voice abuse, acoustic analysis, maximum phonation time, GRBAS, and VHI. Thirteen patients (4.08%) had unilateral vocal nodule and 306 patients (95.9%) had bilateral vocal nodule, the majority of which had a pattern of asymmetry (73.9%). The glottal closure pattern was hourglass in 72.1% of patients, posterior chink in 17.9% of patients, and irregular in 7.9% of patients. The most common occupational category was professional voice users (43.4%). The voice abuse pattern included excessive talking in 96 patients (76.8%), loud voice in 78 (62.4%) patients, and excessive singing in 17 patients (21.6%). The patients showed worse scores in G, B, and S than in R and A for the GRBAS evaluation. The most recommended treatment for vocal nodules was voice therapy. The current clinical data will be helpful for treatment planning for the patients of vocal nodule.

• 한국직업건강간호학회지
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• 제29권4호
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• pp.235-246
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• 2020

Purpose: In Korea, the proportion of female workers among occupational injury is steadily increasing. The purpose of this study was to identify the workplace risk factors that threaten the safety and health of the female workers. Methods: Qualitative study was conducted, using focus group interview. Data were collected from five focus groups of eighteen female workers who were working in the manufacturing, health service, and educational service industries. Results: The seven themes of occupational safety and health risks of women workers are as follows: 1) Workplace with various risks; 2) Sliding, falling, burning, and cutting accidents; 3) Chronically lasting musculoskeletal symptoms; 4) Chemicals that may be harmful to workers; 5) Unprotected infectious disease; 6) Psychological safety accidents(Relationship conflict and emotional labor); 7) Loud, hot, stuffy, scary, and tired. Conclusion: The Occupational Safety & Health (OSH) Act should be rearranged gender sensitively and women's participation in the OSH decision-making process should be guaranteed. OSH education should be properly implemented in the field, and support should be provided for women workers in small businesses. A supportive organizational culture for marriage, pregnancy and childbirth should be established, and the working environment should be provided safely, taking into account gender differences.

• 한국연소학회지
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• 제20권1호
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• pp.32-42
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• 2015

The combustion instability was experimentally investigated in model gas turbine combustor with dual swirl burner. When such instability occurs, a strong coupling between pressure oscillation and unsteady heat release excites a self-sustained acoustic wave which results in a loud sound, and can even cause fatal damage to the combustor and entire system. In present study, to understand the combustion instability with a premixed mixture, the detailed periods of pressure and heat release data in unstable flame mode were investigated by various measurement methods at relatively rich condition and lean condition near flammable limits. Also, to prepare the utilization of synthetic natural gas (SNG) fuel in gas turbine system, an investigation was conducted using a simulated SNG including methane as a reference fuel to examine the effects of $H_2$ content on flame stability. These results provide that the instability due to flash-back behaviour like CIVB phenomenon occurred at rich condition, while the repetition of relighting and extinction caused the oscillation of lean condition near flammable limit. From the analysis of $H_2$ content effects, it is also confirmed that the instability frequency is proportional to the laminar burning velocity at both rich and lean condition.