• Korean Journal of Radiology
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• v.22 no.3
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• pp.464-475
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• 2021

Objective: This study aimed to evaluate the tumor doubling time of invasive lung adenocarcinoma according to the International Association of the Study for Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) histologic classification. Materials and Methods: Among the 2905 patients with surgically resected lung adenocarcinoma, we retrospectively included 172 patients (mean age, 65.6 ± 9.0 years) who had paired thin-section non-contrast chest computed tomography (CT) scans at least 84 days apart with the same CT parameters, along with 10 patients with squamous cell carcinoma (mean age, 70.9 ± 7.4 years) for comparison. Three-dimensional semiautomatic segmentation of nodules was performed to calculate the volume doubling time (VDT), mass doubling time (MDT), and specific growth rate (SGR) of volume and mass. Multivariate linear regression, one-way analysis of variance, and receiver operating characteristic curve analyses were performed. Results: The median VDT and MDT of lung cancers were as follows: acinar, 603.2 and 639.5 days; lepidic, 1140.6 and 970.1 days; solid/micropapillary, 232.7 and 221.8 days; papillary, 599.0 and 624.3 days; invasive mucinous, 440.7 and 438.2 days; and squamous cell carcinoma, 149.1 and 146.1 days, respectively. The adjusted SGR of volume and mass of the solid-/micropapillary-predominant subtypes were significantly shorter than those of the acinar-, lepidic-, and papillary-predominant subtypes. The histologic subtype was independently associated with tumor doubling time. A VDT of 465.2 days and an MDT of 437.5 days yielded areas under the curve of 0.791 and 0.795, respectively, for distinguishing solid-/micropapillary-predominant subtypes from other subtypes of lung adenocarcinoma. Conclusion: The tumor doubling time of invasive lung adenocarcinoma differed according to the IASCL/ATS/ERS histologic classification.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.251-256
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• 1998

근래에 들어와 산업화가 급속히 진행되면서 공해문제가 심각하게 대두된 것과 마찬가지로 전자산업의 발달에 힘입어 전자공학을 응용한 여러 종류의 다양한 장비가 널리 보급됨에 따라 전자파 공해문제가 꾸준히 제기되었다. 이를 전자파 장해 (EMI : Electromagnetic Interference)라고 한다. 특히 컴퓨터 화면에서 전자파가 발생되어 사용자에게 심각한 영향을 준다는 VDT증후군, 전력선 주변의 주민들에게 발생된다는 백혈병, 휴대폰의 사용에 의하여 발생될 수 있다는 뇌암등, 인체에 해로운 효과가 발생된다는 검증된 또는 검증되지 않은 내용이 매스컴에 의하여 그대로 전달됨으로 인하여 전문적 지식이 부족한 일반인들에게 상당한 심리적 압박을 주어 왔다. (중략)

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.420-420
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• 2006

• Proceedings of the Korean Society of Crop Science Conference
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• 2019.04a
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• pp.134-134
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• 2019

• Journal of the Korean Society of Physical Medicine
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• v.11 no.3
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• pp.41-47
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• 2016

PURPOSE: Forward head posture (FHP) is one of the most common postural problems among white-collar workers who perform highly repetitive tasks in the same position. The aim of this study was to research the effects of thoracic and lumbar support fixtures on forward head posture (FHP) during visual display terminal (VDT) work. METHODS: The subjects were 36 healthy male students with no problems in their medical history or respiratory systems. The subjects were randomly assigned to three groups: control group (n=12), thoracic support fixtures (n=12), and lumbar support fixtures (n=12). We conducted a text typing task of the same content for 20 minutes, and evaluated the angles, including the craniovertebra angle (CVA), craniorotation angle (CRA) with photogrammetry. RESULTS: The thoracic and lumbar support fixture groups showed a statistically significant difference at the CVA and CRA to the control group (p<.05), and the post-hoc test showed an increase of the CVA and decrease of the CRA than the control group. However, when we compared the effects of thoracic and lumbar support fixtures on FHP, there was no significant difference in the difference in decrease of the CVA or increase of the CRA (p>.05). CONCLUSION: We determined that VDT work using thoracic and lumbar support fixtures has a positive effect on forward head posture in white-collar workers. Further studies are required to find the more effective location of support fixtures.

• The Journal of Korean Physical Therapy
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• v.15 no.3
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• pp.277-294
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• 2003

The present study attempted to investigate the angle of cervical vertebrae motions of thirty subjects who are seated in front of computers for a long time. The subjects were divided into Group A, B and C, which were for ultrasound treatment and relaxing exercise, for ultrasound treatment and massage, and relaxing exercise and massage respectively. This study made comparisons between groups of different ages and genders before treatment, between groups of different genders by segment before treatment, and between before and after treatment for each group. It also made multiple comparison based on the variance analysis among groups and comparison between Group A and B. From the results of this study, following conclusions were drawn. 1. When comparing the total means of different age groups, female subjects' angle of motions was wider than male subjects' in all age groups except the group at the age of 30-34. 2. When comparing the total means of different segments of cervical vertebrae, female subjects' angle of motions was wider than male subjects' in segment C3-4, C4-5 and C5-6. 3. Group A showed a significant difference from Group B and C in segment C4-5, and only Group C showed a significant difference in the other segments(p<0.05). 4. When comparing the total angle of cervical vertebrae motions between Group A and Group B, there was a slight but not significant difference in the angle(p<0.05).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.24-35
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• 1998

Cumulative trauma disorders(CTDs) have been a growing problems for US and European industries with higher incidence rate every year. The increase and their associated costs has led companies to form committes and implement programs to address this problem. In our country, we have just started to recognize and to work on the problems in industry. This study conducted an ergonomic analysis for typical jobs of ship building industry which was not usually surveyed for CTD problem. A baseline CTD checklist which was supposed to do a risk assessment was developed and applied in this study. Initially, we considered five major parts in the checklist which consisted of personal, frequency, posture, force, and miscellaneous information. Most jobs in ship building industry were much different from typical assembly work and VDT work that have been major part of the previous CTD studies. Specifically, job characteristics in terms of frequency and posture were quite different. There were relatively long cycle time, awkward postures for whole body (not just for upper extremities). Also, CTD risk scores based on checklist were a lot higher than the scores for VDT jobs which was a case of preceding application of the checklist. Specifically, grinding jobs turned out to be the most risky one in terms of CTDs. In conclusion, usual CTD prevention guidelines are not likely to he effective in this type of industry. An individual job based interventions are strongly suggested to have a good control of CTD problems in ship building industry.

• Archives of design research
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• v.12 no.1
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• pp.157-166
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• 1999

With the increase in use of the computer, the VCT syndrome has occured as a new socialJhea/health problem. ErgonomicaI design standards are a for the users to reduce stress and poor physical posture in the human body. In this study. we have suggested design dimensions recommended from previous studies. We also have reviewed users' preference dimenision, and analyzed differences between users' preference dimenision. and the previous design aiteria to verify physical appropriateness. We analyzed how each design dimension was reached and affected the tunan body by objective EMG evaluation. and subjective evaluation of physical discomfort and oorrIort. We have found that keyboard height is very important in a workstation. If the elbow's height is lower than the keyboard's height. it effedS the hand and wrist. If higher, it brings fatigue to the shoulder and neck. As a result of this experiment. we suggested that the height of a keyboard desk for Koreans be 660mm for the fixed type and 540-774mm for the adjustable type. Also other design reoommendations were suggested in the thesis. In ooncIusion, our research will be very important in the database because it provides adjustable ranges to fit user's body types in the various design flekIs.

• Journal of the Ergonomics Society of Korea
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• v.27 no.4
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• pp.59-64
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• 2008

The aims of this study were to compare and analyze two types of deep cervical flexion exercises, craniocervical flexion and cervical flexion, and to ascertain their relative effects on neck and shoulder pain and functional improvement. The participants of the study were individuals who work in sedentary jobs in an office environment. 54 appropriate subjects were chosen and randomly divided into two groups: one group underwent a craniocervical flexion exercise program and the other a cervical flexion exercise program. The six week exercise program consisted of home exercises performed by each subject five times a week and education once a week. Neck-shoulder pain, muscle strengthening, cervical alignment were measured prior to commencement of the exercise programs and again after six weeks. At completion of the six week, both exercise programs decreased neck pain (p<.05). Forward head postures were reduced, and the craniocervical flexion exercise program was more effective in reducing forward head posture (p<.05). The maximum muscle strength and 50% of maximum muscle strength maintaining time of the deep cervical flexor muscles were significantly increased. There were no significant changes of the cervical lordotic curve. The results of this study showed deep cervical flexion exercise was effective in the treatment of neck and shoulder pain, however craniocervical flexion exercise was more effective than cervical flexion exercise.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.1-9
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• 2023

Objective: This study identifies the difference among the heights of a chair's backrest (High, Mid, No), the biomechanical changes chair users undergo over time, and the variables that can measure musculoskeletal disorders, eventually providing information on the appropriate type of backrest. Method: Eleven healthy subjects in their 20s and 30s who had no experience with musculoskeletal disorders or surgical operations within the last 6 months participated in this study. Computer typing tasks were randomly designated and performed according to the type of chair backrest, and evaluation was performed for Flexion-Relaxation Ratio (FRR) analysis after the computer typing tasks. This study used eight infrared cameras (sampling rate: 100 Hz) and nine-channel electromyography (sampling rate: 1,000 Hz). ANOVA with repeated measures was conducted to verify the results, with the statistical significance level being α = .05. Results: Although there was no significant difference in craniovertebral angle (CVA), this study showed time and interaction effects depending on the height of the backrest (p<.05). When working without the backrest, the head-spine angle was lower compared to the chairs with backrest, based on the computer work. As for the head angle, the higher the back of the chair was, the less the head flexion and the body angle became, whereas the body flexion became less when there was a backrest. In addition, the body flexion increased over time in all types of backrests (p<.05). The muscle activity of the upper body tended to be high in the high backrest chair. On the other hand, a lower muscle activity was found with a low backrest. Conclusion: These results show that a chair is more ergonomic when the body angle is correctly set without bending and when it is supported by a low backrest. Accordingly, this study determines that the backrest affects shoulder and neck musculoskeletal disorders during typing and that medium-height backrest chairs can help prevent musculoskeletal disorders, contrary to the expectation that high-backrest chairs are preferable.