• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.4
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• pp.387-393
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• 2020

Objective: This study aimed to investigate the differences in temporary threshold shift (TTS) and recovery patterns according to different types of sound and volume. Methods: TTS and recovery patterns were assessed for eight students after 30-minute exposure to both 70.0 dB and 90.0 dB of factory noise (noise) as well as music. TTS was measured before exposure and two minutes post exposure, and recovery patterns were evaluated every 10 minutes for one hour. The subjects performed activities of daily life and sleeping times as usual but taking drugs or drinking alcohol were prohibited. The experiment was repeated three times with an interval of at least 16 hours. ANOVA and T-test were carried out using SPSS 19.0 for Windows. Results: The hearing threshold of all subjects before exposure was less than 30 dB at all frequencies. Mean TTSs of 70 dB noise and 90 dB noise exposure were 0.14 and 4.48 dB (p<0.001). Meanwhile, the difference in music was insignificant (-0.63 dB and 0.55 dB, p=0.063). A significance in the difference was also found between the mean TTS of music and noise exposure, more obviously at 90.0 dB (p<0.001) than at 70 dB (p=0.232). The TTS differences were found frequency-wise in terms of sound type. Mean TTS by frequency was higher at 4,000 and 6,000 Hz than at other frequencies, and higher in noise than music at the same sound pressure. The TTS difference in each frequency between both sound types was significant at 90 dB (p<0.001). Subjects mostly recovered from TTS in one hour after exposure, but not with 90 dB-noise exposure. Conclusion: TTS and recovery patterns were different depending on the sound type. When exposed to factory noise, TTS was greater and recovery time was longer compared to music at the same sound pressure. These results suggested that the difference in cognitive processes and psychological factors according to the type of sound causes a change in TTS and recovery.

• Journal of radiological science and technology
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• v.45 no.2
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• pp.135-143
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• 2022

In SPECT image, scatter count is the cause of quantitative count error and image quality degradation. This study is to evaluate the accuracy of CT based SC(CTSC) and energy window based SC(EWSC) as the comparison with existing Non SC. SPECT/CT images were obtained after filling air in order to acquire a reference image without the influence of scatter count inside the Triple line insert phantom setting hot rod(^99mTc 74.0 MBq) in the middle and each SPECT/CT image was obtained each separately after filling water instead of air in order to derive the influence of scatter count under the same conditions. For EWSC, 9 sub-energy windows were set additionally in addition to main energy window(140 keV, 20%) and then, images were acquired at the same time and five types of EWSC including DPW(dual photo-peak window)10%, DEW(dual energy window)20%, TEW(triple energy window)10%, TEW5.0%, TEW2.5% were used. Under the condition without fluctuations in primary count, total count was measured by drawing volume of interest (VOI) in the images of the two conditions and then, the ratio of scatter count of total counts was calculated as percent scatter fraction(%SF) and the count error with image filled with water was evaluated with percent normalized mean-square error(%NMSE) based on the image filled with air. Based on the image filled with air, %SF of images filled with water to which each SC method was applied is non scatter correction(NSC) 37.44, DPW 27.41, DEW 21.84, TEW10% 19.60, TEW5% 17.02, TEW2.5% 14.68, CTSC 5.57 and the scatter counts were removed the most in CTSC and %NMSE is NSC 35.80, DPW 14.28, DEW 7.81, TEW10% 5.94, TEW5% 4.21, TEW2.5% 2.96, CTSC 0.35 and the error in CTSC was found to be the lowest. In SPECT/CT images, the application of each scatter correction method used in the experiment could improve the quantitative count error caused by the influence of scatter count. In particular, CTSC showed the lowest %NMSE(=0.35) compared to existing EWSC methods, enabling relatively accurate scatter correction.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.12-18
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• 2023

The effective evacuation strategy according to the accident scenario is crucial to minimize human casualties in the event of toxic gas leak accidents. In this study, the effect of the direction of a building and the location of an industrial complex on the increase in indoor concentration and outdoor diffusion was examined under the same leakage conditions, and effective evacuation criteria were established. In addition, the guidelines for building directions were suggested when constructing buildings that would mitigate human damage caused by chemical accidents. Three scenarios where buildings faced the front, side, and rear of the leakage direction were investigated through CFD simulations. The results revealed that when the building faced the industrial complex, both indoor and outdoor average gas concentrations increased significantly, reaching up to 120 times higher than the other two orientations. Moreover, the indoor space was filled with toxic gas substances more than twice in the same time due to the rapid increase of indoor concentration rate. In cases where the building's windows were positioned at the front, toxic gas stagnation occurred around the building due to pressure differences and reduced flow velocities. Based on our findings, the implementation of these guidelines will contribute to safeguarding residents by minimizing exposure to toxic gas during chemical accidents.

• Journal of Korean Dental Hygiene Science
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• v.1 no.2
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• pp.41-52
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• 2018

The purpose of this study was to examine the state of oral prophylaxis practice among dental hygiene students and their awareness of musculoskeletal diseases in an effort to provide some information on how to strengthen education on treatment posture to manage musculoskeletal diseases and how to raise awareness of musculoskeletal diseases. From November 2 to 13, 2016, a self-administered survey was conducted on 653 sophomores, juniors and seniors with an experience of oral prophylaxis practice. SPSS version 20.0 for Windows was employed to analyze the collected data. The findings of the study were as follows: 1. The largest group that accounted for 37.4% responded that the total number of students undergoing oral prophylaxis practice during a semester was four to six. The biggest group that represented 65.4% answered that the required practice time per student was one to fewer than three hours. 76.0% continued to be in the repeated same posture. 2. As for the posture of patients, supine position was most common for the maxillary sinus, which accounted for 82.2%. And semi-upright position was most common for the mandibular sinus, which represented 49.6%. 3. In regard to the burden of oral prophylaxis practice, 33.9% considered the required for the practice appropriate. 42.3% took the repeated long-lasting posture, and 53.5% were under physical pressure. 55.4% suffered from mental pressure and stress. 4. The most dominant musculoskeletal area that they experienced pain after oral prophylaxis practice was neck with 52.5%; waist with 48.2, shoulders/wrists/hands with 45.5, back with 10.3, buttocks with 4.1, elbows with 2.3, legs with 2.1, ankles/feet with 0.8 and knees with 0.6%. 5. Concerning the maintenance of repeated treatment postures and pain experience, the students who continued to be in the repeated same position underwent more pain than the others who didn't on the shoulders(2.92±1.05), in the waist(3.02±1.01), buttocks(1.75±0.92), elbows(1.55±0.79) and ankles/foot(2.52±1.25). The differences were statistically significant(p<.05, p<.01). 6. As to educational experience on treatment posture and musculoskeletal diseases, 88.8% received education on treatment posture; 87.9%, on what position should be taken in times of cooperation; 46.9%, on musculoskeletal diseases; 51.9%, on carpal tunnel syndrome; 42.3%, on varicose vein. The students who replied education on occupational diseases was necessary accounted for 89.6%. 7. The students who experienced treatment posture education were better aware of the causes of musculoskeletal diseases(3.23±3.00), ways for preventing the diseases(3.33±.834) and how to stretch the body(3.63±.858). The differences were statistically significant(p<.05, p<.001). 8. The students who experienced education on occupational diseases heard more about musculoskeletal diseases(3.27±.965), were better cognizant of the causes of the diseases(3.45±.847), were better aware of how to prevent them(3.55±.805) and found themselves to know how to stretch to prevent the diseases (3.73±.826). The differences were statistically significant(p<.001).

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.51-56
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• 2009

Purpose: Recently, most hospitals are introducing the PACS system and use of the system continues to expand. But small-scaled PACS called MicroPACS has already been in use through open source programs. The aim of this study is to prove utility of operating a MicroPACS, as a substitute back-up device for conventional storage media like CDs and DVDs, in addition to the full-PACS already in use. This study contains the way of setting up a MicroPACS with open source programs and assessment of its storage capability, stability, compatibility and performance of operations such as "retrieve", "query". Materials and Methods: 1. To start with, we searched open source software to correspond with the following standards to establish MicroPACS, (1) It must be available in Windows Operating System. (2) It must be free ware. (3) It must be compatible with PET/CT scanner. (4) It must be easy to use. (5) It must not be limited of storage capacity. (6) It must have DICOM supporting. 2. (1) To evaluate availability of data storage, we compared the time spent to back up data in the open source software with the optical discs (CDs and DVD-RAMs), and we also compared the time needed to retrieve data with the system and with optical discs respectively. (2) To estimate work efficiency, we measured the time spent to find data in CDs, DVD-RAMs and MicroPACS. 7 technologists participated in this study. 3. In order to evaluate stability of the software, we examined whether there is a data loss during the system is maintained for a year. Comparison object; How many errors occurred in randomly selected data of 500 CDs. Result: 1. We chose the Conquest DICOM Server among 11 open source software used MySQL as a database management system. 2. (1) Comparison of back up and retrieval time (min) showed the result of the following: DVD-RAM (5.13,2.26)/Conquest DICOM Server (1.49,1.19) by GE DSTE (p<0.001), CD (6.12,3.61)/Conquest (0.82,2.23) by GE DLS (p<0.001), CD (5.88,3.25)/Conquest (1.05,2.06) by SIEMENS. (2) The wasted time (sec) to find some data is as follows: CD ($156{\pm}46$), DVD-RAM ($115{\pm}21$) and Conquest DICOM Server ($13{\pm}6$). 3. There was no data loss (0%) for a year and it was stored 12741 PET/CT studies in 1.81 TB memory. In case of CDs, On the other hand, 14 errors among 500 CDs (2.8%) is generated. Conclusions: We found that MicroPACS could be set up with the open source software and its performance was excellent. The system built with open source proved more efficient and more robust than back-up process using CDs or DVD-RAMs. We believe that the operation of the MicroPACS would be effective data storage device as long as its operators develop and systematize it.

• Journal of Intelligence and Information Systems
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• v.26 no.4
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• pp.127-148
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• 2020

The data center is a physical environment facility for accommodating computer systems and related components, and is an essential foundation technology for next-generation core industries such as big data, smart factories, wearables, and smart homes. In particular, with the growth of cloud computing, the proportional expansion of the data center infrastructure is inevitable. Monitoring the health of these data center facilities is a way to maintain and manage the system and prevent failure. If a failure occurs in some elements of the facility, it may affect not only the relevant equipment but also other connected equipment, and may cause enormous damage. In particular, IT facilities are irregular due to interdependence and it is difficult to know the cause. In the previous study predicting failure in data center, failure was predicted by looking at a single server as a single state without assuming that the devices were mixed. Therefore, in this study, data center failures were classified into failures occurring inside the server (Outage A) and failures occurring outside the server (Outage B), and focused on analyzing complex failures occurring within the server. Server external failures include power, cooling, user errors, etc. Since such failures can be prevented in the early stages of data center facility construction, various solutions are being developed. On the other hand, the cause of the failure occurring in the server is difficult to determine, and adequate prevention has not yet been achieved. In particular, this is the reason why server failures do not occur singularly, cause other server failures, or receive something that causes failures from other servers. In other words, while the existing studies assumed that it was a single server that did not affect the servers and analyzed the failure, in this study, the failure occurred on the assumption that it had an effect between servers. In order to define the complex failure situation in the data center, failure history data for each equipment existing in the data center was used. There are four major failures considered in this study: Network Node Down, Server Down, Windows Activation Services Down, and Database Management System Service Down. The failures that occur for each device are sorted in chronological order, and when a failure occurs in a specific equipment, if a failure occurs in a specific equipment within 5 minutes from the time of occurrence, it is defined that the failure occurs simultaneously. After configuring the sequence for the devices that have failed at the same time, 5 devices that frequently occur simultaneously within the configured sequence were selected, and the case where the selected devices failed at the same time was confirmed through visualization. Since the server resource information collected for failure analysis is in units of time series and has flow, we used Long Short-term Memory (LSTM), a deep learning algorithm that can predict the next state through the previous state. In addition, unlike a single server, the Hierarchical Attention Network deep learning model structure was used in consideration of the fact that the level of multiple failures for each server is different. This algorithm is a method of increasing the prediction accuracy by giving weight to the server as the impact on the failure increases. The study began with defining the type of failure and selecting the analysis target. In the first experiment, the same collected data was assumed as a single server state and a multiple server state, and compared and analyzed. The second experiment improved the prediction accuracy in the case of a complex server by optimizing each server threshold. In the first experiment, which assumed each of a single server and multiple servers, in the case of a single server, it was predicted that three of the five servers did not have a failure even though the actual failure occurred. However, assuming multiple servers, all five servers were predicted to have failed. As a result of the experiment, the hypothesis that there is an effect between servers is proven. As a result of this study, it was confirmed that the prediction performance was superior when the multiple servers were assumed than when the single server was assumed. In particular, applying the Hierarchical Attention Network algorithm, assuming that the effects of each server will be different, played a role in improving the analysis effect. In addition, by applying a different threshold for each server, the prediction accuracy could be improved. This study showed that failures that are difficult to determine the cause can be predicted through historical data, and a model that can predict failures occurring in servers in data centers is presented. It is expected that the occurrence of disability can be prevented in advance using the results of this study.

• Journal of Korean society of Dental Hygiene
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• v.4 no.1
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• pp.1-17
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• 2004

The purpose of this study is to investigate the actual condition of consciousness that the students in Dept. of dental hygiene who will be engaged in dental hygiene at a dental office in the future have about a clinical training, to see whether there is any difference between the results, and then to provide fundamental data which can be helpful to develop more effective clinical training programs. For this, we investigated consciousness, that 114 daytime school students and evening school students(76 daytime school students and 38 evening school students) in Dept. of dental hygiene in J college have, using questionnaires on clinical training with Self-Administrated Method. SPSS 12.0 for Windows was used to analyze all of the questionnaires, and the results analyzed at meaningful level a=.05 are like followings: 1. The degree of satisfaction on clinical training was high as average 3.30 ; it was high in case of night training as 3.34, and of a dental office in a general hospital and an university hospital as 3.83. The degree of stress caused by clinical training was high as average 3.30, and it means that they are under relatively heavy pressure ; it was shown they got the most heavy stress as 3.39 at night, as 3.68 at a dental clinic 2. The students showed the highest tendency to recognize that clinical training is needed "for learning various clinical case experiences" as average 3.54 ; the students trained at daytime showed the highest average 3.55, and at a clinical hospital, the highest average 3.64. 3. In the study on an actual condition of consciousness about clinical training according to class difference by time(at day time and at night), there is meaningful difference between two kinds of class ; the students trained at day time showed average 2.68 that they don't like to attend, on the other hand the students at night showed higher average 2.84(p<.05). In the study on an actual condition of consciousness about clinical training according to the institutions they are trained, there is meaningful difference at satisfaction on learning method and amount of assignment : they show the highest degree of satisfaction on the learning method in case of working at a dental office in a general hospital and an university hospital as average 3.3(p<.0.1) ; the amount of assignment was shown most high at a dental clinic and a dental office in a general hospital and an university hospital as average 3.00 each(p<.05). 4. In the study of the degree of satisfaction on the clinical training, it has relatively high connections with learning contents(r=.656), learning methods(r=.497), special lessons and supplementary lessons(r=.472), the case they don't like attend at work (r=-.439), discriminatory treatment(r=-.25l), respectability on the senior dental hygienists(r=.464), a social status of a dental hygienist(r=.213), the degree of satisfaction from the relationship with other dental hygienists(r=.274), the degree of understanding which clinical training institutions have on the trained students(r=.494), trainers' ability to teach the students(r=.499). enthusiasm on guiding (r=.523), the amount of assignment(r=.333). 5. In the study on stress they got from a clinical training, it has relatively high connections with learning contents(r=-.399). learning methods(r=-.536), comprehension on training program(r=-.208), special lessons and supplementary lessons(r=-.306), the case they don't like attend at work(r=.467), discriminatory treatment(r=.366), respectability on the senior dental hygienists(r=-.341), a social status of a dental hygienist(r=-.l97), the degree of satisfaction from the relationship with another dental hygienists(r=-.289), the degree of understanding which clinical training institutions have on the trained students(r=-.430), trainers' ability to teach the students(r=-.396), enthusiasm on guiding(r=-.495).

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.42-55
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• 2006

We propose a single Index approach for subsequence matching that supports moving average transform of arbitrary order in time-series databases. Using the single index approach, we can reduce both storage space overhead and index maintenance overhead. Moving average transform is known to reduce the effect of noise and has been used in many areas such as econometrics since it is useful in finding overall trends. However, the previous research results have a problem of occurring index overhead both in storage space and in update maintenance since tile methods build several indexes to support arbitrary orders. In this paper, we first propose the concept of poly-order moving average transform, which uses a set of order values rather than one order value, by extending the original definition of moving average transform. That is, the poly-order transform makes a set of transformed windows from each original window since it transforms each window not for just one order value but for a set of order values. We then present theorems to formally prove the correctness of the poly-order transform based subsequence matching methods. Moreover, we propose two different subsequence matching methods supporting moving average transform of arbitrary order by applying the poly-order transform to the previous subsequence matching methods. Experimental results show that, for all the cases, the proposed methods improve performance significantly over the sequential scan. For real stock data, the proposed methods improve average performance by 22.4${\~}$33.8 times over the sequential scan. And, when comparing with the cases of building each index for all moving average orders, the proposed methods reduce the storage space required for indexes significantly by sacrificing only a little performance degradation(when we use 7 orders, the methods reduce the space by up to 1/7.0 while the performance degradation is only $9\%{\~}42\%$ on the average). In addition to the superiority in performance, index space, and index maintenance, the proposed methods have an advantage of being generalized to many sorts of other transforms including moving average transform. Therefore, we believe that our work can be widely and practically used in many sort of transform based subsequence matching methods.

• Korean Journal of Heritage: History & Science
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• v.52 no.2
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• pp.292-307
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• 2019

Buddhists have always tended to adorn and embellish Buddhist statues and their surrounding spaces in order to exhibit the grandeur and sublime nature of the Buddha. The various kinds of splendid instruments and implements used in such ornamentation are collectively called jangeomgu in Korean. Thus, the term jangeomgu encompasses articles used to decorate Buddhist statues, halos, and baldachin, as well as Buddhist banners and wind chimes, which are generally hung outside a building. Wind chimes are still widely used at Buddhist temples. In China, judging from various structures such as the Wooden Stupa of Yongningsi in Luoyang and the Dunhuang Caves, wind chimes began to be used around the sixth century. As for Korea, Buddhism was first introduced from China during the Three Kingdoms Period, and Koreans accordingly began to build Buddhist temples and buildings. It would appear that wind chimes came to be used around the time that the first temples were built. The oldest extant wind chime in Korea is the gilt-bronze wind chime of Baekje, discovered at the Mireuksa Temple Site in Iksan. In general, Korean wind chimes dating from the Three Kingdoms Period are classified into two general types according to their shape and elevation, i.e., those shaped like a Buddhist bell and those shaped like a trapezoid. As these two forms of wind chimes have influenced each other over time, those made during the Goryeo dynasty, having inherited the style, structure, and design of the preceding period, display such features. At the same time, the artisans who produced wind chimes pursued technical development and adopted free, yet not extravagant, designs. In particular, Goryeo wind chimes are characterized by original designs created through exchanges with other Buddhist art forms of the same period, such as the embossed lotus design band of Goryeo bells; the bullmun design, which served to display the grandeur of the royal family; the samhwanmun design, which consisted of decorating the interior of a Goryeo incense burner with three holes; Sanskrit designs; and designs inspired by the windows and doors of stone pagodas. In this way, the production of Goryeo wind chimes developed with a focus on purpose while being free of formal constraints. This study started out from the fact that the largest number of Korean wind chimes were produced during the Goryeo dynasty. Therefore, research on wind chimes should be based on those of the Goryeo dynasty, especially since fewer relevant studies have been conducted compared to studies on other forms of Buddhist art. For the purposes of this study, the reasons for the production of wind chimes will be examined first, followed by an examination of the various styles of Korean wind chimes. Then, based on the findings of this investigation, the development and characteristics of the wind chimes produced during the Goryeo dynasty will be explored for each period.

• Journal of Chest Surgery
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• v.39 no.9 s.266
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• pp.692-698
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• 2006

Background: Owing to the fact that the average life span has increased and the progress in medical science has been made, the number of patients with chronic renal failure (CRF) who have to take hemodialysis (HD) has been going up gradually. Accordingly, it is considered to be as a significant issue to obtain blood vessels which can be used repetitively and supply enough blood flows. Therefore, there have been various kinds of study on an inosculation rate andfactors influencing it following an arteriovenous fistula (AV fistula) and lots of studies are ongoing for the purpose of escalating the inosculation rate. The authors analyzed the effects of short-term result, age, sex, diabetes and hypertension on arteriovenous inosculations in 134 anatomical snuffbox operated subjects among the patients who have taken an AV fistula at this center. Material and Method: Based on 134 patients who underwent an AV fistula at the department of thoracic surgery of this center from July, 2000 to May, 2004, the difference in arteriovenous inosculation rate was compared and analyzed depending or age (discriminated by 65-year-old), sex and the condition of the presence or absence of diabetes and hypertension. Correlation analyses were conducted for each parameter and statistical tests were performed by using SPSS for windows Release 11.0.1, which were determined to be statistically significant if p value was below 0.05. Result: The total number of operations was 169 including 35 of re-operations. The male/female rate was 70 : 64 (52% : 48%). The average age was $56.3{\pm}12.26$ years and there were 33 (24%) old aged patients above 65-year-old; there were 103 (71%) patients with hypertension and 90 (67%) patients with diabetes. Overall arteriovenous inosculation rate was $93{\pm}2.4%,\;91{\pm}2.7%,\;89{\pm}3.0%$ at 6, 12, 24 months, respectively. The arteriovenous inosculation rate of above 65-year-old patient group was $85{\pm}4.8%,\;80{\pm}5.8%,\;80{\pm}5.8%$ and below 64-year-old patient group's was $85{\pm}4.8%,\;80{\pm}5.8%,\;80{\pm}5.8%$ at given time points, respectively, which showed higher inosculation rate in below 64-year-old patient group with a statistical significance (p=0.0034). However, no statistical significance was found between the patients with hypertension and diabetes and the patients with no complication. In addition, there was no statistical significance in inosculation rate between male and female. Conclusion: The arteriovenous inosculation ratewas higher in the treated patient below 64-year-old than in the treated patient above 65-year-old. Thus it is advantageous for increase in long-term inosculation rate to obtain hemodialysis routes at an early age. The conditions of sex and the presence or absence of diabetes and hyper- tension do not make statistically significant effect on the arteriovenous inosculation rate.