This paper investigates the stress-reducing preventive maintenance model through numerical experiments. The preventive maintenance model is used to analyze the relationship between related conditions and variables to gain insight into the efficient operation of the system when performing preventive maintenance in real-world situations. Various preventive maintenance models have been developed over the past decades and their complexity has increased in recent years. Increasing complexity is essential to reflect reality, but recent models can only be interpreted through numerical experiments. The stress-reducing preventive maintenance is a newly introduced preventive maintenance concept and can only be interpreted numerically due to its complexity, and has received little attention because the concept is unfamiliar. Therefore, for information purposes, this paper investigates the characteristics of the stress-reducing preventive maintenance and the relationship between parameters and variables through numerical experiments. In particular, this paper is focusing on the economic feasibility of stress-reducing preventive maintenance by observing changes in the optimal preventive maintenance period in response to changes in environmental stress and the improvement factor. As a result, when either the environmental stress or the improve effect of stress-reducing preventive maintenance is low, it is not necessary to carry out the stress-reducing preventive maintenance at excessive cost. In addition, it was found that the age reduction model is more economical than the failure rate reduction model.

이 연구의 목적은 노화 관련 근감소증과 노쇠함의 정의와 원인뿐만 아니라 규칙적인 운동과 올바른 영양을 통한 예방과 지연을 탐색하고자 한다. 근감소증과 쇠약함은 노화에 따른 근량과 근기능이 감소하여 쇠약함과 악액질, 골다공증, 대사적 증후군과 조기 사망을 일으키는 것으로 알려져 있다. 두 질환은 활성화 산소로 알려진 산화적 스트레스 양의 증가에 따른 근육 내부에서의 신경계 손상과 단백질 합성 부족, 부적절한 영양 및 신체활동의 부족 등과 관련성이 있었다. 그러한 증후군을 예방하고 개선하기 위한 올바른 영양과 신체활동(유산소운동, 저항운동 등)의 역할과 중요성이 강조되고 있다. 결론적으로 노화와 관련한 근감소증과 노쇠함을 예방하고 극복하기 위한 가장 유익한 방법으로서 규칙적인 운동을 포함한 양질의 단백질 공급을 제안한다.

Korea’s elevator industry is one of the world’s eighth-largest industrial sectors and the third largest in the world by new installations. This year, the number of elevators has exceeded 700,000, and the number of new installations is 30,000-40,000 every year. However, the news of elevator-related accidents is reported continuously through the media and the accident rate is not decreasing. In particular, among the recent accidents related to elevators, accidents related to elevator workers are increasing, causing social problems. This year, the National Assembly’s Environmental Labor Relations Commission’s National Auditors lost five lives a year and 12 elevator workers were killed in fall and stenosis accidents during the installation, maintenance and replacement of the elevators for about two years since 2018. It took place to adopt the representatives of four domestic elevator companies as witnesses. An elevator worker is a collective term for workers involved in the design, manufacturing, installation, replacement, maintenance, inspection, management, and supervision related to the elevator industry, and the related accidents are called elevator worker accidents. Analysis of elevator-related accidents in the past has shown that the fault of the user accounted for 70% of the total, and the fault of the worker accounted for about 2.5%, and the accident occurred to the user or the user due to carelessness of the worker during the lift-related work. Currently, elevator-related accidents are reported by the Korea Elevator Safety Agency under Article 48 of the Elevator Safety Management Act under the Ministry of Interior and Safety. If deemed necessary for the prevention and prevention of recurrence of an elevator accident, the cause and condition of the elevator accident may be investigated. However, the current draft law is limited only to elevators after installation inspection, and is separated from the Ministry of Employment and Labor’s data on accidents occurring in the manufacturing and installation stages related to the elevator industry. This study analyzes the recent safety accidents of elevator workers and prepares safety measures to prevent them through the risk analysis, and also draws out the problems and improvements of the current elevator worker accident investigation to find the elevator worker accident rate that is on the increase trend.

PURPOSES : The purpose of this study is to evaluate the performance of an ultra-thin asphalt pavement as a preventive maintenance approach through laboratory tests. METHODS : An ultra-thin asphalt pavement of 2 cm wearing course thickness comprising modified asphalt and aggregate is a preventive maintenance method used for asphalt pavements. A mix design was carried out to determine the optimum aggregate gradation and asphalt contents. A dynamic immersion test was performed to evaluate the water-resistance of the ultra-thin asphalt pavement. A wet track abrasion test and a cohesion test were conducted to examine the applicability of the ultra-thin asphalt pavement in surface treatment. The performance of the ultra-thin asphalt pavement was evaluated through wheel loading tests, such as Hamburg wheel-tracking and third-scale model mobileloading simulator (MMLS-3). RESULTS : An optimum binder content of 4.9% was obtained in the ultra-thin asphalt mixture from the Marshall mix design. The waterresistance tests indicated a 70% dynamic immersion coverage rate of the ultra-thin asphalt pavement. The wet track abrasion test showed an abrasion rate of 0.0107 g/cm2, and the cohesion tests indicated a 19.0 kg·cm average cohesion at 30 min of operating time and 21.4 kg·cm average cohesion at 60 min of operating time. From the Hamburg wheel-tracking test, a 16.56 mm rut depth at 20,000 wheel passing was obtained. Finally, a 5.87 mm rut depth at 300,000 number of wheel passing was detected from the MMLS-3 test. CONCLUSIONS : The water-resistance of the ultra-thin asphalt pavement satisfied the recommended guidelines of the Korean Ministry of Land, Infrastructure and Transport. In addition, the applicability of the ultra-thin asphalt pavement as a surface treatment met the standard of the International Slurry Surfacing Association. Furthermore, the deformation performance of the ultra-thin asphalt pavement was 1.5 times better than that of the straight asphalt pavement, based on the results of the wheel-loading tests. Hence, it is estimated that an ultra-thin asphalt pavement has a high performance in the preventive maintenance of asphalt pavement, even though the cracking resistance was not evaluated in this study.

The number of elevators in Korea has surpassed 700,000 units in 2019, which is the 8th in the world by number of installed units and 3rd in the world by new units. The word 'lift' is a representative word, and the category includes elevators, escalators, dumb waiters, and moving walks. Those who live in the city will experience using elevators once or twice a day, and these elevators are becoming an indispensable means of transportation when using high-rise apartments or subways. However, such a convenient elevator also has a lot of risks that threaten the safety of the user and actually cause many accidents every year. In particular, escalators (including moving walks), which account for as little as 5% of all elevators, account for 70% of all elevator accidents. According to Heinrich's chain of thought theory, accidents are caused by a combination of factors, which are divided into five stages: Stage 1: Genetic Factors and Social Environment, Stage 2: Individual Defects, Stage 3: Unsafe behavior and Unsafe conditions, Stage 4: Accident, Stage 5: Injury. Heinrich said that three of these five phases, unsafe behavior and unsafe conditions, require safety management and efforts to prevent accidents. In escalator accidents, the analysis of accident cases that have occurred so far will be related to unsafe behaviors and unsafe conditions, and the effective management of these causes of accidents will enable safer and more convenient use of escalators. This study analyzed accident cases of elevator users, focusing on escalator accidents over the last 10 years (2010 ~ 2019), and safety management to prevent safety accidents of elevator users by analyzing the behavior of actual users and questionnaires of experts in related fields. The method was studied.

어린이공원은 아이들에게 심리적 안정감을 주는 중요한 장소이나 2018년도 서울시 내 안전도 C등급을 부여받은 공원 중 어린이공원이 절반이상을 차지한다는 결과가 나왔다. 이에 본 연구는 CPTED와 공원이 위치한 지역의 시설환경을 같이 분석하여 어린이공원의 안전도에 영향을 미치는 요인을 분석하는 것을 목적으로 한다. 연구 대상지는 2018년도 서울시 내 안전도 C등 급과 A등급을 부여받은 어린이공원으로 선정되었다. 관련 논문과 문헌을 통해 CPTED 개념과 도시 범죄특성을 고찰하고 국내외 CPTED 가이드라인을 검토하였다. 고찰한 내용을 기반으로 CPTED 체크리스트, 이용자 행태조사, 공원이 위치한 지역의 시설환경을 같이 분석하고 종합하여 결과를 도출하였다. 연구 결과 어린이 공원의 안전도에 있어 CPTED와 공원이 위치한 지역의 시설환경 둘 다 영향을 미치는 것으로 판단되었다. 본 연구의 결과는 어린이공원을 계획하고 조성하는데 있어 유용한 기초자료로 활용될 수 있을 것이라 기대한다.

To investigate the effects of antioxidant activities and hair loss prevention of extracts from Platycodon grandiflorum, we’ve prepared chloroform (CF) and ethylacetate fractions (EA) extracted from P. grandiflorum. In the results of DPPH radical scavenging assay, the two fractions showed dose-dependent antioxidant activities. Furthermore, in the ABTS assay, the two fractions exhibited the inhibitory effect over 90% at 10, 50, 100, 200 mg/mL. To investigate the inflammation inhibitory effect, we used RAW264.7 cells, these extracts were inhibited inflammatory reaction by suppressing the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in dose-dependent manner. In the assay of HaCaT cells’ proliferation, the 24 hr treatment of the extracts significantly accelerarted cell proliferation in the range of concentrations used. The two fractions inhibited the proliferation of Malssezia furfur, the bacteria induce the dandruff. Finally, the CF could significantly inhibit the DHT production at 1, 10, 50, 100 μg/mL, but EA showed the inhibitory effect at the concentration over 50 μg/mL. The overall results of this study suggest that the chloroform (CF) and ethylacetate fractions (EA) from P. grandiflorum could be a useful raw material for the hair loss prevention products.

Background: Fall-related injuries in older adults are a major health problem, and the risks and mechanisms of these injuries should be affected by race, culture, living environment, and/or economic status. Objects: Research articles have been systematically reviewed to understand fall-related injuries in older adults in South Korea. Methods: 128 published research papers have been found through the Korea Citation Index and the Korean Studies Information Service System, and reviewed in various perspectives, including incidents, fall death rates, medical costs, causes, injury sites and types, locations where falls occurred, prevention strategies, scholarly fields interested in fall injuries, and the role of physical therapy. Results: Fall-related injuries were found to be more common in women than in men, and the number of incidents increased with age, with the highest rate found in individuals over 85 years old. Risk of fall injury was associated with education level, comorbidities, and fear of falling. Common places where falls occurred included the bathroom, living room, stairs, and hallway. Common types of injury included bruises, fractures, and sprains in the lower extremities. Intervention strategies included exercise programs, education, and protective clothing. Scholarly fields interested in fall-related injuries in older adults included medicine, nursing, physical therapy, occupational therapy, physical education, pharmacology, oriental medicine, biomedical engineering, design, clothing, and textiles. Physical therapy intervention using proprioceptive neuromuscular facilitation has been used to improve one’s balance. Conclusion: Any movement during the activities of daily living can lead to a fall. Physical therapists are highly educated to analyze human movements and should be involved in more research and practices to solve fall-related injuries in older adults.