Postural stability can reduce the likelihood of critical slip and fall accidents in workplaces. The present study aimed to analyze the effect of shoes type on the ability of postural control during quiet standing. The effect of workload on the body balance was also of primary concern. Thirteen healthy male undergraduate students participated voluntarily in the experimental study. Standing on a force plate with wearing slippers, sports shoes, or safety shoes, two-axis coordinate on subjects’ center of pressures (COP) was obtained in the two levels, rest and workload. For the workload level, subjects performed treadmill exercise to reach the predetermined level of physical workload. By converting the position coordinates of COPs, the postural sway length in both anterior-posterior (AP) axis and medio-lateral (ML) axis was assessed. ANOVA results showed that, in AP direction, wearing slippers significantly increased the postural sway length compared to wearing sports shoes or safety shoes. No significant difference in the mean sway length in AP axis was observed between sports shoes and safety shoes. In ML direction, both the workload and the shoes type did not significantly affect the mean length of postural sway. However, the postural sway length increased marginally with the slippers especially during the workload condition. This study explains wearing slippers may interfere with the ability of postural control during quiet standing. Physical workload decreases the ability of postural stability further.

Postural instability can increase the likelihood of hazardous slip and fall accidents in workplaces. The present study intended to extend understanding of the effect of abnormal neck posture on postural control during quiet standing. The effect of body fatigue on the postural control was also of primary concern. Twelve healthy undergraduate students volunteered to participate in the experiment. Standing on a force platform with the neck neutral, flexed, extended, or rotated, subjects’ center of pressures (COP) were measured under the two levels of body fatigue. For the fatigue condition, Subjects exercised in a treadmill to meet the predetermined level of body fatigue. Analyzing the position coordinates of COPs, the length of postural sway path was assessed in both medio-lateral (ML) axis and anterior-posterior (AP) axis. Results showed that, in AP direction, neck extension or rotation significantly increased the sway length as compared with neck neutral. Neck extension led to greater sway length compared to neck rotation. Neck flexion did not differ from neck neutral. The sway length in the AP direction also became significantly larger as the body fatigue accumulated after treadmill exercise. In ML direction, as compared to neutral posture, the neck extension, flexion, or rotation did not significantly affect the length of postural sway path. However, the sway length seemed to increase marginally with the neck extended during the fatigued condition. This study demonstrates that abnormal neck posture may interfere with postural control during standing. The ability to maintain postural stability decreases significantly with the neck extended or rotated. Body fatigue leads to postural instability further.

An injection unit is the important part which guide the melted resine into the mold. Once injection molding is performed, there will be a pressure of 33 MPa built up inside of injection cylinder body. It was confirmed that the crack occurs by internal stress on the 9 mm material when the machine is used for long time. Because the cylinder rod has material thickness of 9~12 mm during manufacturing process on the cylinder body, there would be 3 mm thickness differences. In this experiment, IDEAS, a computer aided structure analysis software, is used to present the optimized design condition. Insert rod with inner diameter of 9 mm was set as a normal and vary 3 mm in x, y axis direction. When the internal pressure of 33 MPa occurs at the injection unit, fix the x and y direction and find out the stress acting only in z axis. It was confirmed that the stress of 45~82 N/mm 2 was built up when the left of cylinder body had been set 9 mm by using a structure analysis. Also, it has been verified the thickness of the material on the left need to be greater and equal than 12 mm to prevent a material crack by an internal stress.

Loss of postural stability can possibly lead to slip and fall accidents in the number of workplaces and everyday life. This study was aimed to examine the effects of whole body fatigue and partially limited visual field on the ability of maintaining postural balance during quiet standing. A group of twelve healthy male subjects participated in the experiment. Before and after experiencing the whole body fatigue induced by bicycling exercises, the position coordinates of subject’s center of pressure (COP) were obtained under the two levels of visual field condition (i.e., open visual field and limited visual field). Four levels of the whole body fatigue examined were rest, 300watt, 600watt, and 900watt. Position coordinates of COPs measured on a force plate were then converted into the total length of postural sway path in both the medio-lateral (ML) direction and the anterior-posterior (AP) direction. Two-way ANOVA result showed that the length of sway path in the AP direction became significantly larger as the whole body fatigue accumulated. Post-hoc test revealed statistically significant differences between rest and 900watt and between 300watt and 900watt. The significant increase of the sway length was also found when the visual field was partially obstructed by the boxes. In the ML direction, however, there was no statistically significant difference of the postural sway in both the AP and ML directions. The results imply that the ability of maintaining postural stability can be reduced significantly due to such tasks along with whole body fatigue. The postural balance can also be impaired by the limited visual field.

As a measure of health, the percentage of body fat has been utilized for many ergonomist, physician, athletic trainers, and work physiologists. Underwater weighing procedure for measuring the percentage of body fat is popular and accurate. However, it is relatively expensive, difficult to perform and requires large space. Anthropometric techniques can be utilized to predict the percentage of body fat in the field setting because they are easy to implement and require little space. In this concern, the purpose of this study was to find a regression model to easily predict the percentage of body fat using the anthropometric circumference measurements as predictor variables. In this study, the data for 10 anthropometric circumference measurements for 252 men were analyzed. A full model with ten predictor variables was constructed based on subjective knowledge and literature. The linear regression modeling consists of variable selection and various assumptions regarding the anticipated model. All possible regression models and the assumptions are evaluated using various statistical methods. Based on the evaluation, a reduced model was selected with five predictor variables to predict the percentage of body fat. The model is : % Body Fat = 2.704-0.601 (Neck Circumference) + 0.974 (Abdominal Circumference) -0.332 (Hip Circumference) + 0.409 (Arm Circumference) - 1.618 (Wrist Circumference) + ε. This model can be used to estimate the percentage of body fat using only a tape measure.

Mental fatigue is inevitable in the workplace. Since mental fatigue can lead to decreased efficiency and critical accidents, it is important to manage mental fatigue from the viewpoint of accident prevention. An experiment was performed to evaluate mental fatigue using the formant frequency analysis of human voices. The experimental task was to mentally add or subtract two one-digit numbers. After completing the tasks with four different levels of mental fatigue, subjects were asked to read Korean vowels and their voices were recorded. Five vowel sounds of “아”, “어”, “오”, “우”, and “이” from the voice recorded were then used to extract formant 1 frequency. Results of separate ANOVAs showed significant main effects of mental fatigue on formant 1 frequencies of all five vowels concerned. However, post-hoc comparisons revealed that formant 1 frequencies of “아” and “어” were most sensitive to mental fatigue level employed in this experiment. Formant 1 frequencies of “아” and “어” significantly decrease as the mental fatigue accumulates. The formant frequency extracted from human voice would be potentially applicable for detecting mental fatigue induced during industrial tasks.

This study was performed to design and develop an ergonomic equipment for strawberry sorting and packing in agricultural working environments. Potential risk of work related musculo-skeletal disorders associated with farm workers performing strawberry sor

Korean railway has run about 110 years since 1989 and played a great role of industrialization in Korea. It is known that rail transport systems have many advantages of being more safe, energy-efficient, and environment-friendly, as compared to other tran

We investigated the effects of trunk twist on postural stability during manually handling flat ties. Ten male subjects participated in this study. While handling 5kgf and 10kgf bundles of flat ties respectively, their centers of pressure (COPs) were measu

In this study, we examined the effects of background and underline on the readability of displayed text The background was placed on every other line and the underline was done with every line of the text The effect of adding color to the background and u

This study was aimed to understand the effects of perturbed floor surface on human postural stability while standing. Ten subjects were asked to stand quietly on the surface with two angles of inclination (0° and 5°), two contamination conditions(dry and

본 논문은 "풋 스캐너"와 "족압분석 시스템"을 이용하여 획득한 측정 데이터에서 새로운 보행분석 평가 방법을 제안하였다. 기존의 많은 연구자들에 의해서 보행시 발바닥의 육안적 검사와 압력분포의 분석 방법이 많이 논의되었다. 또한 연구자들은 압력곡선, 압력중심 궤적과 압력중심에서의 속도에 관해서 관심을 가져왔다. 그러나 이런 실험결과들은 실험환경과 피험자의 조건에 의해 의존된다. 결론적으로 우리는 이런 문제를 해결하기 위해 특별한 에너지 변수 등을 고려해야만 한다. 운동 에너지와 충격량 변수는 보행 분석에 활용될 수 있으며, 본 논문의 결과는 8명의 피험자들의 실험을 통하여 새로운 변수의 유용성을 확인하였다. 새로운 변수의 유용성을 확인하였다.

Recently, in Seoul there is a growing interest in the L type gutter between the street and the sidewalk because the broken gutter spoils the appearance of the city. The gutter has been viewed as an unimportant attached facility of the road despite an important drainage facility. Also, the gutter lost function by various deterioration actions is becoming hideous objects of streets. Accordingly, many engineers recognized problems about the gutter and tried to seek for solution. In this study, we desired to confirm that the inside of the gutter concrete was not deteriorated even if the surface of the gutter concrete was deteriorated by the de-icing salts. We could obtain thirty core specimens deteriorated by de-icing salts in Seongbuk-gu which is old downtown, has many hills such as Arirang-Hill, Miari-Hill, etc. in Seoul and test compressive strength. It was confirmed that the compressive strength of the gutter concrete follows normal distribution and it is statistically significant 1% level that the population mean of the compressive strength of the gutter concrete is more than 18MPa.

본 연구에서는 왕호장 열매 추출물(FSR)의 항염증 효과를 측정하였다. 왕호장 열매 추출물은 RAW 264.7 macrophage 세포에서 염증 사이토카인(1L-1β, IL-6, TNF-α)의 발현을 억제하였으며, 농도 의존적으로 NO 생성을 억제하고, 그 효과는 100 µg/mL 농도에서 51%로 나타났다. 뿐만 아니라, iNOS와 COX-2의 mRNA와 단백질 발현을 모두 억제함을 확인하였다. 따라서 왕호장 열매 추출물은 항염증 효능을 갖는 화장품 소재로서의 개발 가능성이 클 것으로 기대된다.

본 연구의 목적은 봄맞이 추출물의 미백 효능을 밝히는 것에 있다. 그 효능을 검증하기 위하여 tyrosinase 활성 및 B16F1 멜라노마 세포를 이용한 멜라닌 생성 양 억제 정도를 조사하였다. 그 결과 봄맞이 추출물은 우수한 tyrosinase 억제 효능을 가지며 특히, 멜라닌 생합성 저해 효과는 25μg/mL 농도에서 그 생성 억제율이 32%로 나타났고, B16F1 멜라노마 세포에서 농도 의존적으로 멜라닌 생성 양을 억제하는 것을 확인하였다. 세포 내에서의 미백 메커니즘을 밝히기 위해 western blot 방법을 이용하였으며, 25μg/mL 농도의 봄맞이 추출물이 microphthalmia associated transcription factor (MITF), tyrosinase, TRP-1의 발현을 억제함을 확인하였다. 위 결과를 통해, 봄맞이 추출물의 우수한 미백 효능을 확인할 수 있었으며, 향후 미백 화장품 소재로서 개발 가능성이 클 것으로 기대된다. 이 발견을 바탕으로, 봄맞이 추출물의 미백효능에 대한 유전자 수준 또는 추가적인 메커니즘 연구를 통해 기능성 화장품 뿐 아니라, 의약제품, 건강기능식품으로의 활용을 기대한다.

본 연구는 미백 소재 개발을 위하여 강진향(Dalbergia odorifera T. Chen) 추출물에서 분리한 활성물질인 biochanin A의 멜라닌 생성에 연관된 효과를 알아보았다. Biochanin A는 B16F1 melanoma 세포에서 농도의존적으로 멜라닌 양을 억제하였으며, 멜라닌 생합성 저해 효과는 10 μg/mL 농도에서 멜라닌 생성 억제율이48%로 나타났다. Western blot을 이용하여 microphthalmia associated transcription factor (MITF),Tyrosinase, Trp-1와 Trp-2의 발현을 억제함을 확인하였다. 따라서 biochanin A는 미백 효능을 갖는 화장품소재로서의 개발 가능성이 클 것으로 기대된다.

This study was investigate to evaluate the phosphate uptake rate of green algae in relation to diurnal rhythm and algae control method. The phosphate uptake rates of Chlorella vulgaris and Ankistrodesmus convolutus increased in light period and decreased in dark period. On the contrary, those of Chlamydomonas sp. showed a peak in the late dark period. The differences among species in phosphate uptake in relation to diurnal rhythm were due to the severe competition among species and seemed to alleviate the competition for nutrient supplies. The compound of CellCaSi, Ca and Fe showed the effective removal of the phosphorus. The extracts from rice and barley straw exhibited a significant effect on the growth inhibition of Microcystis aeruginosa.