Safe operation of freight vehicles is an important issue for drivers, cargo, and other road users. In particular, the center of gravity of a freight vehicle is directly related to the stability of the vehicle, and this can fluctuate in real time depending on weight changes. Every time a freight vehicle loads or unloads cargo, its center of gravity changes, and these changes greatly affect the risk of vehicle rollover. We researched a continuous center of gravity measurement system for freight vehicles for safe driving.

소형 선박(<499 GT)이 전체 선박의 46%를 지배하고 있어 상대적으로 많은 CO2 배출가스를 가지고 있다고 결론지을 수 있다. 최 적의 Trim 조건에서 운전하면 선박의 저항을 감소시킬 수 있어 온실가스가 적게 발생할 수 있다. Trim을 최적화하는 가장 저렴한 방법 중 하 나는 최적의 Longitudal Center of Gravity(LCG)를 얻기 위해 무게 분포를 조정하는 것이다. 따라서 본 연구에서는 소형 선박의 저항에 대한 LCG 변화의 영향을 경험적 및 수치적 해석을 통해 연구하고자 한다. 선체를 설계하는 Savitsky 경험식은 Maxsurf Resistance의 방법으로 사용 된다. 수치해석에는 STAR-CCM+ 상용 CFD(Computational Fluid Dynamics) 소프트웨어가 사용되지만 최종적으로 선박 설계 과정 이후 최적의 LCG를 얻기 위해 전체 저항을 비교한다. 결론적으로 Froude Number 0.56에서는 수치해석에 의해 전체 길이(LoA) 46.2%에서 최적의 LCG를 달성하고 Froude Number 0.63에서는 43.4% LoA를 달성하여 29.2% LoA에서 기준점에 비해 최대 41.12% - 45.16%의 상당한 저항 감소를 얻을 수 있다.

본 연구의 목적은 Y-Balance Test(YBT)를 통하여 무게부하 증가가 동적 균형에 미치는 영향을 알아보고자 하였다. 연구의 대상자는 20-30대 남녀 성인 18명(연령: 23.17±1.72 years, 신장: 172.46 ±9.84 cm, 체중: 73.39±11.44 kg 다리길이: 88.89±5.69 cm)이 실험에 참여하였다. 동적 균형 측정을 위하여 YBT를 통하여 도달거리와 종합점수, COP 변인들을 측정하여 결과를 도출하였다. 연구결과로 YBT 시 후내측과 후외측 도달거리, 종합점수에서 무게부하일 때 동적 균형이 향상되었다. COP 결과로, 전방 도달 동안 전후진폭, 좌우 COP속도, COP 면적은 오른발에서 무게부하 시 동적 균형이 향상되었지 만, 후내측 도달 동안 차이가 없었고, 후외측 도달 동안 좌우진폭은 왼발에서, 전후 COP속도는 왼발, 좌우 COP속도와 COP속도는 좌우발에서, COP 면적은 좌우발의 무게부하 시 동적 균형이 향상되었다.

Recently 3d printer industry has two demands. first is color 3d printing. second is mass production using 3d printer that has large bed. According to previous studies, 3D printed objects have different weights depending on filament colors. 3D printed tensile specimens with filaments of various colors were checked to see they had the same weight. If so, we wanted to see it was statistically significant. As a result, we found that the weight of 3D printed objects was statistically significantly different depending on the filament color. The average weight of 3d printed objects is: Black(8.63g), Blue(8.58g), Yellow(8.53g), White(8.48g), Natural(8.46g), Green (8.45g), Red(8.42g).

Many manufacturers applying third party logistics (3PLs) have some challenges to increase their logistics efficiency. This study introduces an effort to estimate the weight of the delivery trucks provided by 3PL providers, which allows the manufacturer to package and load products in trailers in advance to reduce delivery time. The accuracy of the weigh estimation is more important due to the total weight regulation. This study uses not only the data from the company but also many general prediction variables such as weather, oil prices and population of destinations. In addition, operational statistics variables are developed to indicate the availabilities of the trucks in a specific weight category for each 3PL provider. The prediction model using XGBoost regressor and permutation feature importance method provides highly acceptable performance with MAPE of 2.785% and shows the effectiveness of the developed operational statistics variables.

물체의 무게감은 감각 측면에서 중요하게 다뤄진 연구 주제로 물체의 무게뿐만 아니라, 크기, 색상, 재질 등의 영 향을 받아 크기-무게, 색상-무게 그리고 재질-무게 왜곡 현상을 갖는 것으로 알려져 있다. 온도는 우리의 일상생활에 매우 중요한 환경적 요소이나, 물체의 온도가 무게감에 어떤 영향을 미치는지에 대해 충분한 연구가 되어 있지 않다. 본 연구는 물체의 온도가 무게감에 미치는 영향을 파악하고자 하였다. 이를 위해 본 연구는 물체의 온도, 무게를 조정하기 용이한 스테인리스 컵을 무게감 측정 물체로 선정하였고, 온도 5 수준(0, 9, 20, 40, 70℃), 무게 2 수준(250, 400g)의 조합으로 10개의 스테인리스 컵을 준비하였다. 무게감 실험에는 건강한 20대 남여 40명이 참여하였고, modulus 방법에 따라 기준 컵 대비 주어진 컵의 무게감을 평가하였다. 실험 데이터의 분석 결과, 온도, 무게 모두 무게감에 유의한 영향을 주는 것으로 나타났다. 온도가 무게감에 주는 영향은 물체의 무게에 따라 다르게 나타났는 데, 적은 컵 무게(250g)로 컵의 무게감이 작은 경우 컵의 온도는 무게감에 영향을 주지 않았다. 반면, 큰 컵 무게 (400g)에서 낮은 온도에서 무게감이 커지는 것으로 나타났다. 이의 결과는 온도의 물체 무게감의 영향이 크기-무게 왜곡에 따라 달라짐을 의미한다.

Background: A backpack is available equipment for moving some objects. Most studies have found that the appropriate weight limit of backpack for students is between 10% to 15% of their body weight (BW). However, Some students should carry a backpack heavier than 15% of BW. Therefore, It is associated with abnormal shoulder and neck posture on students. Objects: This study tested the effects that various amounts of weight carried by university students in their backpacks had on their cervical posture and electromyography of neck muscle. Methods: The subjects consisted of 12 students (6 male, 6 female) in university. There were three loading conditions tested: no backpack, a backpack that weighed 10% and 15% of the student’s BW. The dependent variables were the craniovertebral angle (tragus to C7) and the neck muscle activities (sternocleidomastoid, upper trapezius). All 12 subjects were asked to walk while wearing a backpack for 5 minutes and were then instructed to rest for 2 minutes. Results: When assessing the craniovertebral angle, the results of this study were significantly decreased in the order of 0%, 10%, and 15%. And then, there were significantly increased electromyography of neck muscles that comparison of the weight of 10% and 15% on 0%. It was found that as the weight of the backpack increased, the craniovertebral angle decreased (p < 0.05) and the muscle activities increased (upper trapezius p = 0.012, sternocleidomastoid p = 0.013). Conclusion: Our study recommended that some students shouldn’t carry on over the 15% backpack of own weight, and also they should distribute backpack load to equal on body for optimal posture.

Winged scapular (WS) causes muscle imbalance with abnormal patterns when moving the arm. In particular, the over-activation of the upper trapezius (UT) and decrease in activity of the lower trapezius (LT) and serratus anterior (SA) produce abnormal scapulohumeral rhythm. Therefore, the SA requires special attention in all shoulder rehabilitation programs. In fact, many previous studies have been devoted to the SA muscle strength training needed for WS correction. Objects: The purpose of this study was to investigate the effect of shoulder girdle muscle and ratio according to the angle of shoulder abduction and external weight in supine position. Methods: Twenty three WS patients participated in this experiment. They performed scapular protraction exercise in supine position with the weights of 0 ㎏, 1 ㎏, 1.5 ㎏, and 2 ㎏ at shoulder abduction angles of 0˚, 30˚, 60˚, and 90˚. The angle and weight applications were randomized. Surface electromyography (EMG) was used to collect the EMG data of the SA, pectoralis major (PM), and UT during the exercise. The ratio of PM/SA and UT/SA was confirmed. Two-way repeated analyses of variance were used to determine the statistical significance of SA, PM, and UT and the ratios of PM/SA and UT/SA. Results: There was a significant difference in SA according to angle (p<.05). Significant differences were also identified depending on the angle and weight (p<.05). The angle of abduction at 0˚, 30˚ and weight of 2 ㎏ showed the highest SA activity. However, there was no significant difference between PM and UT (p>.05). There was a significant difference between PM/SA and UT/SA in ratio of muscle activity according to angle (p<.05). Significant differences were found at PM/SA angles of 30˚, 60˚ and 90˚ (p<.05). For UT/SA, significant difference was only observed at 90˚ (p<.05). Conclusion: Based on the results of this study, in order to strengthen the SA, it was found to be most effective to use 1 and 1.5 ㎏ weights with abduction angles of 0˚ and 30˚ at shoulder protraction in supine position.

In this study, we estimated the applicability of length-weight relationship-based biomass calculations by comparison of body length of genus Polyarthra collected from different habitats. Through the comparison, we also tested availability of representative species-specific biomass value of Polyarthra which is often used without length measurement. Polyarthra samples were collected from rivers (Han River and Nakdong River) and reservoir (Paldang Reservoir), and the body length was measured for statistical comparison among habitats and biomass calculations using different equations suggested previously. According to the results, the body length of Polyarthra spp. was significantly different among sampling sites, and the necessity of body length measurement for rotifer species in each situation has been suggested rather than using the representative biomass values which is fixed without considering time and space. Comparison of suggested biomass calculations based on our measured Polyarthra body length, the equation suggested by McCauley showed more reasonable range of biomass values than that suggested by EPA. In addition, in order to calculate more accurate biomass, it is necessary to measure the body length of rotifers, at least more than 44 individuals to reduce error probability to less than 5% with 99% probability. However, since direct measurement of rotifers biomass is limited, it is considered that further analyses are required for more precise application of rotifer biomass of which has high variability due to complex morphologies and species-specific cyclomorphosis often induced by biotic and abiotic factors in the habitats.

본 연구는 잎마늘 생산을 위한 마늘 주아의 최적 주아 크기와 재식밀도를 알아보기 위함이다. 첫번째 실험에서 0.2g 이상의 주아를 대주아로, 이하를 소주아로 나눈 후 대주아는 13,680bulbils/m2와 18,240bulbils/m2, 소주아는 18,240bulbils/m2와 22,800bulbils/m2의 재식밀도로 치상하였다. 발아율, 초장과 총 수확량을 측정하였다. 두번채 실험에서, 200립의 박피된 주아의 길이, 폭, 생체중과 건물중는 발아시, 발아기와 발아율의 상관를 분석하기 위해 측정되었다. 첫번째 실험에서, 발아율은 대주아에서 가장 높았다. 잎마늘 재배를 위해 재식밀도18,240bulbils/ m2가 가장 높은 발아율 때문에 가장 적당한 재식밀도였다. 수확량의 경우 생체중과 건물중 모두 대주아가 소주아에 비해 2.8배 가량 높은 것을 알 수 있었다. 주아의 형태적 특성과 생체중과 건물중 및 폭간은 정의 상관을 보였다. 또한 발아율은 생체중과 폭간의 정의 상관을 보였다. 그리고 발아시와 발아기는 생체중과 폭간의 부의 상관을 보였다. 그럼으로, 결론적으로, 적정 재식밀도는 18,240bulbils/m2의 재식 밀도와 0.2g 이상의 주아 크기였다. 그러나, 더 두껍고 두 무거운 주아가 더 높은 더 빠른 발아율을 이끌 수 있다.

The purpose of this paper is to suggest the strategical lifting postures able to alleviate imbalanced EMG amplitude leading to an increase in low back muscle fatigue while lifting asymmetric load dynamically. Eleven male subjects are required to lift symm

This study is aimed to show that an asymmetric load in the frontal plane leads to an increase in low back loading and fatigue in comparison with a symmetric load when workers lift an external weight by investigating previous studies and verifying the phen