• The Journal of Korean Medicine
• /
• v.29 no.1
• /
• pp.134-145
• /
• 2008

Objectives : This study investigated the relationship between drinking, smoking and stress of workers by analyzing heart rate variability. The subjects were workers in the automobile manufacturing industry. Methods : The subjects consisted of 21,239 and 19,999 industrial workers who had received health examination by Korean oriental medicine and submitted questionnaires about drinking history and smoking history, during 8 months from April to November. The subjects were categorized into drinking history and smoking history. The heart rate variability was measured for five minute at rest using SA-3000P (Medicore) and reported stress severity as stress index, stress resistance and fatigue. We analyzed the relationship between drinking, smoking and stress into frequencies, $x^2$-test using the SPSS Ver. 12.0. Results : Regarding the relationship between drinking and stress index orstress resistance, there was no statistically significant difference, but regarding the relationship between drinking and fatigue, the drinker group had a significantly higher level of fatigue than the non-drinker group. There was a statistically significant difference in stress index, stress resistance and fatigue between the current-smoker group and others. Stress resistance of the current-smoker group had lower levels than the non-smoker group or ex-smokers. On the other hand, stress index and fatigue of the current-smoker group had higher levels than the non-smoker group or ex-smokers. Conclusions : The above results revealed that drinking and smoking could put workers under a lot of stress. Smoking workers were especially apt to be under stress and had difficulty in alleviating stress.

• Korean Chemical Engineering Research
• /
• v.46 no.6
• /
• pp.1043-1051
• /
• 2008

In polyolefin processes melt index (MI) is the most important controlled variable indicating product quality. Because of the difficulty in the on-line measurement of MI, a lot of MI estimation and correlation methods have been proposed. In this work a new dynamic MI estimation scheme is developed based on system identification techniques. The empirical MI estimation equation proposed in the present study is derived from the $1^{st}$-order dynamic models. Effectiveness of the present estimation scheme was illustrated by numerical simulations based on plant operation data including grade change operations in high density polyethylene (HDPE) processes. From the comparisons with other estimation methods it was found that the proposed estimation scheme showed better performance in MI predictions. Using the model predictive control method based on the present dynamic MI estimation model, MI values are estimated and compared with those of MI setpoints. From the numerical simulation of the proposed control system, it was found that significant reduction of transition time and the amount of off-spec during grade changes were achieved.

• Journal of muscle and joint health
• /
• v.14 no.1
• /
• pp.26-32
• /
• 2007

Purpose: The purpose of this study was to determine if osteoarthritis patients would benefit in terms of pain, fatigue, difficulty with physical activity, joint stiffness, and flexibility of the joints from a structured self-help program. Method: This self-help program was carried out 2-3 hours once a week for 6 weeks in 2005-2006, and evaluated in one group pretest-posttest pre-experimental design. The subjects of this study who were diagnosed osteoarthritis were recruited at two different Community Health Centers in Kangwon. The subjects who agreed with the purpose of this study and participated both pretest and post-test were 55 patients. Mean age is 63.48 (9.48) years, mean duration of disease is 7.95 (7.66) years. The self-help program was consisted of weekly health contract, exercise, health education, group discussion, group counseling, and recreation. At every meeting, researcher and trained public health nurse evaluated the program, and prepared the next program. The measurement tools were pain rating scale (0-10), fatigue rating scale (0-10), Korean WOMAC (Western Ontario and McMaster University Osteoarthritis) Index, ruler, and goniometer. Results: At the completion of 6 weeks of self-help program, the subjects reported significantly less pain and difficulty with physical activity and more flexibility in both shoulder and knee joints compared to pretest. Conclusion: The self-help program would be helpful on pain, physical activity, and joint flexibility for arthritis patients.

• Korea Trade Review
• /
• v.42 no.6
• /
• pp.155-176
• /
• 2017

As an increasing number of the FTA, there have also been increasing interests in FTA utilization. It is critical to understand and implement the rules of origin for FTA utilization appropriately. However, due to the spaghetti bowl effect, the restrictiveness index, which is a measure of the degree of difficulty of meeting Product-Specific Rule(PSR) of origin, gets increased. Furthermore, there is a distortion in the method of calculating the correct restrictiveness index. Therefore, we implemented an enhanced method in a context of fishery product to correctly measure the restrictiveness index of Product Specific Rules (PSR) among the rules of origin.

• Journal of Korean Biological Nursing Science
• /
• v.20 no.1
• /
• pp.11-19
• /
• 2018

Purpose: The purposes of this study were to perform items analysis using the classical test theory (CTT) and the item response theory (IRT), and to establish the validity and reliability of the Korean version of pressure ulcer prevention knowledge. Methods: The 26-item pressure ulcer prevention knowledge instrument was translated into Korean, and the item analysis of the 22 items having an adequate content validity index (CVI), was conducted. A total of 240 registered nurses in 2 university hospitals completed the questionnaire. Each item was analyzed applying CTT and IRT according to 2-parameter logistic model. Response alternatives quality, item difficulty and item discrimination were evaluated. For testing validity and reliability, Pearson correlation coefficient and Kuder Richardson-20 (KR-20) were used. Results: Scale CVI was .90 (Item-CVI range= .75-1.00). The total correct answer rate for this study population was relatively low as 52.5%. The quality of response alternatives was found to be relatively good (range= .02-.83). The item difficulty of the questions ranged form .10 to .86 according to CTT and -12.19 to 29.92 according to the IRT. This instrument had 12-low, 2-medium and 8-high item difficulty applying IRT. The values for the item discrimination ranged .04-.57 applying CTT and .00-1.47 applying IRT. And overall internal consistency (KR-20) was .62 and stability (test-retest) was .82. Conclusion: The instrument had relatively weak construct validity, item discrimination according to the IRT. Therefore, the cautious usage of a Korean version of this instrument would be recommended for discrimination because there are so many attractive response alternatives and low internal consistency.

• The Journal of the Korea Contents Association
• /
• v.22 no.4
• /
• pp.677-688
• /
• 2022

Precarious employment is negatively associated with mental health including depression. The aim of the study is to suggest the multidimensional definition of precarious employment and examine its impacts on depression. Using the fifth save of the Korean Working Condition Survey, we first measured six different dimensions of employment precariousness: temporariness, disempowerment, vulnerability, difficulty exercising rights, unpredictability of working times, and low wage. All of six precariousness indicators consisted of a scale from 0 to 100. Then, we conducted logistic regression to examine the association between employment precariousness and depression. For men, the risk of depression increased by 3.1%, 1%, and 0.5%, respectively, for each one point increase in vulnerability, difficulty in exercising rights, and unpredictability of working times. For women, the risk increased by 0.5%, 2.3%, and 0.8%, respectively, for each one point increase in temporariness, vulnerability, and difficulty in exercising rights. Our findings suggest that not only a secure employment contract, but also their substantive labor rights should be guaranteed for health for workers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.7A
• /
• pp.515-522
• /
• 2009

In this paper, a novel transmission scheme with spatial modulation is proposed for coded orthogonal frequency division multiplexing (OFDM). The multiple-input multiple-output (MIMO) technique, so-called spatial modulation (SM), divides input data into antenna index and data signals, transmitting data signals through the specific antenna chosen by the antenna index. In order to retrieve data stream at the receiver, SM needs to detect the antenna index which means that data signals are transmitted via a certain antenna. For this reason, it should be guaranteed that channel matrix is orthogonal. For the real environment, a MIMO channel has difficulty in maintaining orthogonality due to spatial correlation. Moreover, the receiver of the conventional SM is operated by hard decision, so that this scheme has a limit to be adopted for practical systems. Therefore, soft-output demappers for the conventional and proposed schemes are derived to detect antenna index and data stream by soft decision, and a novel transmission scheme combined with spatial modulation is proposed to improve the bit error rate (BER) performance of the conventional scheme.

• Journal of Technologic Dentistry
• /
• v.18 no.1
• /
• pp.73-94
• /
• 1996

This study was aimed for evaluating the validity of relative-productivity index on the basis of working hour(RPHW index) designed by author as new productivity index and drawing up a plan of bettering productivity to cope with financial difficulty of dental laboratories. Fortyeight dental laboratories extracted by cluster-sampling method form all the dental laboratories in Seoul were subjected for this study. And in each of them, the term of establishment which was divied into three group as short-term, mid-term and long-term group, the scale of dental laboratory which as divided into two group by number of dental technician as small-scale group and large-scale group, the salary system which was composed of salary criteria, pay according to ablility criteria and collectiveagree, the salary level, simple labor productivity index(SLP index), relative-productivity index on the basis of worker number(ROWN) and relative-productivity index on the basis of working hour(RPWH index) were surveyed through the self-administractive questionaires. The results as follows : Most of dental laboratories(93.6%) were managed by non-professional managers. The establishment rate per year of dental laboratory was the increase. The mean number of employees of dental laboratories was $7.00{\pm}3.90$ person. The ratio of smallscale group(under the 5 employees) was 42.6% and as the term of establishment was shorter, the ratio of small-scale group was higher. The mean establishment area of dental laboratories was $24.49{\pm}10.97$ unit and the mean establishment area per head of dental laboratories was $4.05{\pm}3.90$ unit. The estabilshment area and area per head were not significantly associted with the term of establishment, but as the term of establishment was shorter, the estabkishment area per head was slightly wider. The establishment area per head in small-scale group was significantly wider than large-scale group(over the 6 emplayees) The salary criteria(54.4%), pay according to ability(79.2)m ability criteria(77.1%) and collectiveagree(79.2%) as salary systems were used in the most of all dnetal laboratoies. The all salary systems were not significantly associated with the term of establishment and the scale of dental laboratories. The monthly mean salary level of dental laboratoies was $125.64{\pm}31.06$ milion won. The monthly salary level was not significantly associated with the term of establishment and the scale of dental laboratores. But the monthly salary level in the short-term group and the small-scale group were slightly lower than others. The SLP index, the RPWN index and the RPWH index of dental laboratories were $132.16{\pm}48.41$, $382.41{\pm}128.76$ and $76.06{\pm}25.11$, respectively. The SLP, the RPWN and the RPWH of dental laboratories were not significantly associated with the term SLP, the RPWN and the RPWH of dental laboratories were significantly associated with the area of dental laboratory and the salary level. Except for only the association salary criteria among salary system with RPWH of dental laboratories, all other salary system were not associated with the SLP, the RPWN and the RPWH of dental laboratories.

• The Journal of Korean Physical Therapy
• /
• v.21 no.3
• /
• pp.1-8
• /
• 2009

Purpose: The purpose of this study was to examine the functional category, the item structure and the model-data fit of the neck disability index (NDI) of neck pain subjects by performing a Rasch rating scale analysis. Methods: The data was obtained from the assessments of 71 college students (males: 27, females: 44) with neck pain. The data of the NDI was applied to the Rasch's rating scale model to estimate the difficulty of items, the goodness-of-fit of each item, the separation reliability and index, and the rating scale. Results: The 'sleep' item showed misfit and nine items were founds to be fits for self-reporting of disability due to neck pain. The most difficult item of the remaining 9 items was 'work' and the easiest item was 'headache'. The transformation formula score=(logit score+7.10)/(7.10+0.11)$\times$100. The 6 response levels of the NDI were validated according to the structure of the rating scale. The item and subject reliability of the separation reliability was 0.97 and 0.85, respectively. Conclusion: We proved that the NDI for self-reporting of disability of daily activities due to mild neck pain was valid and reliable. This study suggests that individuals with mild neck pain may be assessed by using the modified NDI that does not include the 'sleep' item in the 10 items of NDI.

• Korean Journal of Clinical Laboratory Science
• /
• v.40 no.2
• /
• pp.129-134
• /
• 2008

Obstructive sleep apnea syndrome (OSAS) is occurred by apnea by the obstruction of upper trachea while sleeping, followed by repetitive drop on arterial oxygen saturation ($SpO_2$). Therefore, the present study was focused on relation between $SpO_2$ of while having difficulty in breathing and clinical characteristics of OSAS while sleeping. The study took place at Ewha women university Mokdong hospital with 149 subjects (male 121, female 28) who were examined for polysomnography (PSG) from May 2007 to February 2008. All subjects were adhered to electrodes and sensors to measure electroencephalogram (EEG), electrooculogram (EOG), chin & leg electromyogram (EMG), airflow at nasal and oral cavities, breathing movement of chest and abdominal snoring sound and $SpO_2$. Lowest $SpO_2$ in male was meaningfully low with higher body mass index (BMI), louder snoring sound and thick neck circumference (p<0.01). While mean $SpO_2$ based on the degree of AHI did not show significant difference, lowest $SpO_2$ was significantly low with high AHI (p<0.001). Also, lowest $SpO_2$ was closely correlated with BMI (r=-00.343, p<0.001), snoring sound (r=0.177, p<0.05), apnea index (r=-0.589, p<0.001), hypopnea index (r=-0.336, p<0.001) and apnea-hypopnea index (r=-0.664, p<0.001). $SpO_2$ was closely related to clinical characteristics of OSAS, like male, BMI, snoring sound and neck circumference. Also, polysomnography accompanied by recent development of sleep study is considered as critical test to diagnose OSAS, decide the severity of illness, and evaluate the treatment plan.