• Title/Summary/Keyword: Co-working

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A Study on IoT/ICT Convergence Smart Safety Management System for Safety of High Risk Workers (고위험 직업군의 안전을 위한 IoT/ICT융합 스마트 안전관리 시스템에 관한 연구)

  • Kim, Seungyong;Hwang, Incheol;Kim, Dongsik;Moon, Byungmoo;Oh, Seyong
    • Journal of the Society of Disaster Information
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    • v.15 no.1
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    • pp.39-48
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    • 2019
  • Purpose: This study aims at developing and implementing Smart Safety Management System based on IoT/ICT Convergence for safety of high-risk groups working at disaster or industrial field. Its functions are as follows. Method: We will develop three devices for keeping the safety of high-risk jobs: Sensor of inactivity, Lora based Refitting technology for communication between high-risk workers, and Lora Gateway for monitoring entire situations. Then we will test three devices in respect of their functions, and propose their applicabilities in the field. Results: The system can send and receive safety tags and danger signals by which sensor technology can detect dangerous state of workers. And its command terminal was developed by low-power wireless communication technology and LoRa Gateway, which can fulfill the lifting functions between safety tags. And, furthermore, the command terminal can monitor dangerous situations of disaster sites in real time and can perform the preemptive rescues. Conclusion: This study proves the functional efficacy of Smart Safety Management System for worker safety in various high-risk occupational groups, and also suggests ways to secure worker safety in disaster area and various high risk industrial sites.

A study on the normal project duration development for the construction of multi-utility tunnel in the existing city (기존시가지의 공동구 건설을 위한 표준공기 산정에 대한 연구)

  • Lee, Seong-Won;Lee, Pil-Yoon;Byun, Yo-Seph;Cho, Choong-Yeun;Lee, Min-jae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.12
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    • pp.677-685
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    • 2018
  • In construction, schedule management is the basic but important step, for the effective schedule management, the preparation of the reasonable schedule table should be prioritized. In the design stage, the optimal construction period can be selected through comparison of various conditions and construction methods considering weather conditions and site characteristics. But, At the planning phase, it is difficult to select the effective method and calculate the proper construction period by the basic data(D/B) analysis. In this paper, the construction method considering characteristics of each type and conditions of existing city was selected. For the reasonable duration calculation, we analyzed the unit schedule for RC method for open type and Shield TBM method for tunnel type. The normal project duration of construction assuming of 1,200m of extension and every 200m of ventilation was prepared by integrating each unit schedule. It was analyzed that it took 893 days for the open type and 616 days for the tunnel type. The results of this study will help to make type selection and normal project duration more easily in the planning phase. If it is linked to the design stage, it will be easy to estimate the process and construction cost.

Association Between Job Stress and Fatigue Symptoms Among Fire-Fighting Officials (소방공무원의 직무스트레스와 피로수준과의 관련성)

  • Lee, Kwang-Sung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.2
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    • pp.496-506
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    • 2021
  • This study examined the relationship between job stress and fatigue symptom of fire-fighting officials. The study subjects were 330 fire-fighting officials working at five fire stations in the D metropolitan city. The study survey was a structured self-administered questionnaire from September 1 to October 31, 2019. The level of fatigue symptoms and job stress were significantly higher (p<.0.001). By the sub-region, the level of fatigue symptoms and job demand were significantly higher (p=0.046), but the decision latitude, the supervisor support, and co-worker support were lower (p=0.006, p<0.001, and p<0.001, respectively). The level of fatigue symptom showed a significant positive correlation with the total score of job stress (r=0.348, p<0.05) and the job demand (r=0.301, p<0.05). In contrast, it showed a significant negative correlation with the decision latitude (r=-0.306, p<0.05), supervisor support (r=-0.340, p<0.05), and co-worker support (r=-0.355, p<0.05). Multivariate logistic regression showed that the odds ratio of the high-risk fatigue group was significantly higher in the high-risk group of job stress than in the low group of job stress (ORs=3.03, 95% CI=1.13~8.12). These findings suggest that the level of fatigue symptoms of fire-fighting officials is related significantly to job stress.

Production of Methane from Anaerobic Fermentation of Marine Macro-algae (해조류의 혐기성 발효를 이용한 메탄 생산)

  • Kim, Jeong-Min;Lee, Yeung-Ho;Jung, Sung-Hoon;Lee, Jin-Tae;Cho, Moo-Hwan
    • Clean Technology
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    • v.16 no.1
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    • pp.51-58
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    • 2010
  • Methane was produced from the anaerobic digestion of marine macro-algae. Elemental analysis was first performed to estimate the theoretical methane production of three macro-algae (Undaria pinnatifida, Laminaria japonica, Hizikia fusiformis). Three algae were found to contain C 34 ~ 36%, H 5%, O 37 ~ 43%, N 2 ~ 4%, S 0.4 ~ 0.7%, and ash 14~21%, and the theoretical methane content was in the range of 56 ~ 60%, which can produce 442 ~ 568 mL $CH_4$ per g of volatile solid (VS). Using the biological methane potential (BMP) test, we found that L. japonica resulted in the highest yield of methane (52%). Moreover, various operational conditions, such as algae amount, pH, salinity, particle size, and pre-treatment, were investigated in order to find an optimal condition of anaerobic digestion. At pH 8.0, the autoclaved L. japonica (5g VS/200 mL), when used without washing salt, produced 268.5 mL/g VS which is 65% of the theoretical methane productions. Furthermore, using a CSTR (with the working volume of 7 L out of the total volume of 10 L), we have successfully operated the reactor for 65 days and obtained maximum methane production rate of 1.4 L/day with purity of 70%.

Fabrication of High Density and High Uniformity Irradiation Light Source for Exposure Curing System Using 365 nm and 385 nm Wavelength SMD LED and High Transmittance Silicone Resin TIR Bar Type Lens (365 nm 및 385 nm SMD LED와 TIR 바형 렌즈를 이용하는 고밀도 고균일성 특성의 경화용 광원모듈 제작 )

  • Pil Hong Jeong;Beom Jin Kim;Yeong Jin Kim;Dong Gyu Jeon;Hyo Min Kim;Jae Hyeon Kim;Hyeong Min Kim;Gyu Seong Lee;Kawan Anil;Eung Ryul Park;Soon Jae Yu;Min Jun Ann;Do Won Hwang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.4
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    • pp.394-399
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    • 2024
  • An irradiator is developed using two UVA wavelength ranges of SMD LEDs as a curing light source. This module has dimensions of 545×111×300 mm3 and is equipped with a TIR bar-shaped lens made of PDMS silicone resin. The developed irradiator offers high uniformity, with 89% in the centerline of the horizontal axis direction, for two different wavelength ranges of 365 nm and 385 nm. The radiation intensity from the light source module shows highly directional characteristics, and the irradiator provides a maximum irradiance of 1,634 mW/cm2 at a working distance of 50 mm. During the initial 5 minutes of operation, the irradiance experiences a rapid decrease. However, this issue is addressed by optimizing the LED's current reduction characteristics and managing the Transistor's temperature rise in the constant current circuit. After continuous operation for approximately 60 minutes. The highest temperature, near the central part of the irradiating surface, reaches 69.7℃, while the lowest temperature, near the edges, is 41.1℃.

Measurement and analysis of tractor emission during plow tillage operation

  • Jun-Ho Lee;Hyeon-Ho Jeon;Seung-Min Baek;Seung-Yun Baek;Wan-Soo Kim;Yong-Joo Kim;Ryu-Gap Lim
    • Korean Journal of Agricultural Science
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    • v.50 no.3
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    • pp.425-436
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    • 2023
  • In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m2), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10-4, 2.01×10-4, and 6.85×10-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10-2, 1.63, and 2.59×10-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

Hybrid Natural Orifice Transluminal Endoscopic Cholecystectomy in Dogs: Transgastric, Transcolonic and Transvaginal Approaches (개에서 자연개구부를 통한 하이브리드 내시경적 담낭절제술: 경위장관, 경결장 및 경질 접근법)

  • Kim, Soo-Hyun;Jeong, Seong-Mok;Shin, Sa-Kyeng;Kim, Seong-Su;Shin, Beom-Jun;Lee, Jae-Yeon;Park, Ji-Yeong;Kim, Myung-Cheol;Kim, Young-Il;Lee, Sang-Il;Kim, Ji-Yeon
    • Journal of Veterinary Clinics
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    • v.28 no.5
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    • pp.497-505
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    • 2011
  • Natural orifice transluminal endoscopic surgery is a newly emerging technique recently, with its many potential advantages in clinical practice. Cholecystectomy by Hybrid NOTES in this work, performed with single working channel endoscope in conjunction with a laparoscopic grasping forceps in dogs, is a "bridge" between laparoscopic procedure and pure NOTES. Three different approaches for cholecystectomy were carried out; transgastric, transcolonic and transvaginal. In all three approaches, abdominal opening was made by a 5 mm trocar, followed by making pneumoperitoneum of 4 mmHg with $CO_2$ insufflator. Transgastric cholecystectomy, single working channel endoscope was advanced to the peritoneal cavity through gastric incision in antral region made by endoscopic needle knife. Endoscope was retroflexed to visualize the gall bladder. Transcolonic access, incision for endoscopic entry was done at right ventral wall of descending colon, 15 cm inside from the anus. Incision in transvaginal access was made at right-ventral region, just caudal to the caudal tubercle. With the simple traction by the laparoscopic grasping forceps, good visualization of surgical field was obtained in all three groups. Cystic duct and artery were ligated with endoclips; for complete gall bladder dissection from liver, L-knife was used. Closure of incision sites were done in transgastric and transcolonic cholecystectomy by endoclips, not in transvaginal approach.

A Study on Estimating Shear Strength of Continuum Rock Slope (연속체 암반비탈면의 강도정수 산정 연구)

  • Kim, Hyung-Min;Lee, Su-gon;Lee, Byok-Kyu;Woo, Jae-Gyung;Hur, Ik;Lee, Jun-Ki
    • Journal of the Korean Geotechnical Society
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    • v.35 no.5
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    • pp.5-19
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    • 2019
  • Considering the natural phenomenon in which steep slopes ($65^{\circ}{\sim}85^{\circ}$) consisting of rock mass remain stable for decades, slopes steeper than 1:0.5 (the standard of slope angle for blast rock) may be applied in geotechnical conditions which are similar to those above at the design and initial construction stages. In the process of analysing the stability of a good to fair continuum rock slope that can be designed as a steep slope, a general method of estimating rock mass strength properties from design practice perspective was required. Practical and genealized engineering methods of determining the properties of a rock mass are important for a good continuum rock slope that can be designed as a steep slope. The Genealized Hoek-Brown (H-B) failure criterion and GSI (Geological Strength Index), which were revised and supplemented by Hoek et al. (2002), were assessed as rock mass characterization systems fully taking into account the effects of discontinuities, and were widely utilized as a method for calculating equivalent Mohr-Coulomb shear strength (balancing the areas) according to stress changes. The concept of calculating equivalent M-C shear strength according to the change of confining stress range was proposed, and on a slope, the equivalent shear strength changes sensitively with changes in the maximum confining stress (${{\sigma}^{\prime}}_{3max}$ or normal stress), making it difficult to use it in practical design. In this study, the method of estimating the strength properties (an iso-angle division method) that can be applied universally within the maximum confining stress range for a good to fair continuum rock mass slope is proposed by applying the H-B failure criterion. In order to assess the validity and applicability of the proposed method of estimating the shear strength (A), the rock slope, which is a study object, was selected as the type of rock (igneous, metamorphic, sedimentary) on the steep slope near the existing working design site. It is compared and analyzed with the equivalent M-C shear strength (balancing the areas) proposed by Hoek. The equivalent M-C shear strength of the balancing the areas method and iso-angle division method was estimated using the RocLab program (geotechnical properties calculation software based on the H-B failure criterion (2002)) by using the basic data of the laboratory rock triaxial compression test at the existing working design site and the face mapping of discontinuities on the rock slope of study area. The calculated equivalent M-C shear strength of the balancing the areas method was interlinked to show very large or small cohesion and internal friction angles (generally, greater than $45^{\circ}$). The equivalent M-C shear strength of the iso-angle division is in-between the equivalent M-C shear properties of the balancing the areas, and the internal friction angles show a range of $30^{\circ}$ to $42^{\circ}$. We compared and analyzed the shear strength (A) of the iso-angle division method at the study area with the shear strength (B) of the existing working design site with similar or the same grade RMR each other. The application of the proposed iso-angle division method was indirectly evaluated through the results of the stability analysis (limit equilibrium analysis and finite element analysis) applied with these the strength properties. The difference between A and B of the shear strength is about 10%. LEM results (in wet condition) showed that Fs (A) = 14.08~58.22 (average 32.9) and Fs (B) = 18.39~60.04 (average 32.2), which were similar in accordance with the same rock types. As a result of FEM, displacement (A) = 0.13~0.65 mm (average 0.27 mm) and displacement (B) = 0.14~1.07 mm (average 0.37 mm). Using the GSI and Hoek-Brown failure criterion, the significant result could be identified in the application evaluation. Therefore, the strength properties of rock mass estimated by the iso-angle division method could be applied with practical shear strength.

A Study on Load-carrying Capacity Design Criteria of Jack-up Rigs under Environmental Loading Conditions (환경하중을 고려한 Jack-up rig의 내하력 설계 기준에 대한 연구)

  • Park, Joo Shin;Ha, Yeon Chul;Seo, Jung Kwan
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.1
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    • pp.103-113
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    • 2020
  • Jack-up drilling rigs are widely used in the offshore oil and gas exploration industry. Although originally designed for use in shallow waters, trends in the energy industry have led to a growing demand for their use in deep sea and harsh environmental conditions. To extend the operating range of jack-up units, their design must be based on reliable analysis while eliminating excessive conservatism. In current industrial practice, jack-up drilling rigs are designed using the working(or allowable) stress design (WSD) method. Recently, classifications have been developed for specific regulations based on the load and resistance factor design (LRFD) method, which emphasises the reliability of the methods. This statistical method utilises the concept of limit state design and uses factored loads and resistance factors to account for uncertainly in the loads and computed strength of the leg components in a jack-up drilling rig. The key differences between the LRFD method and the WSD method must be identified to enable appropriate use of the LRFD method for designing jack-up rigs. Therefore, the aim of this study is to compare and quantitatively investigate the differences between actual jack-up lattice leg structures, which are designed by the WSD and LRFD methods, and subject to different environmental load-to-dead-load ratios, thereby delineating the load-to-capacity ratios of rigs designed using theses methods under these different enviromental conditions. The comparative results are significantly advantageous in the leg design of jack-up rigs, and determine that the jack-up rigs designed using the WSD and LRFD methods with UC values differ by approximately 31 % with respect to the API-RP code basis. It can be observed that the LRFD design method is more advantageous to structure optimization compared to the WSD method.

Occupational Stress of Hospital Workers (병원종사자의 직업성 스트레스에 관한 연구 - 서울시내 500병상 이상 병원종사자를 중심으로 -)

  • Lee, Woo-Cheon
    • Korea Journal of Hospital Management
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    • v.3 no.1
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    • pp.1-33
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    • 1998
  • The purpose of this thesis is to study theoretical access to the methods that have been used for the research of occupational stress, thereby providing management methods of occupational stress of hospital workers. With a stress model of hospital workers set up from the viewpoint of organization management, 929 sets of questionnaires were collected from intern doctors, resident doctors, nurses, nursing aides, pharmacists, medical technicians, workers in patient affairs(reception and medical insurance workers), administrators and clerks from the 8 hospitals in Seoul with more than 500 beds. Upon variance analysis, correlation analysis and regression analysis of the collected questionnaires, this work examined how differences in stress caused by specific occupations and formulated a method of stress management for the hospital workers. The results are as follows. 1) If some duties of the nurses suffering from role-overloaded stress are transferred to the nursing aides dissatisfied with insufficient role, the two grunting groups can be satisfied at the same time. It is also necessary to transfer some jobs of the overloaded workers in patient affairs to the administrators, or the other way around. To reduce stress of conflict and ambiguity of role caused by the obscure division of roles between the workers, the role of each occupation should be delineated and the clear division of roles should be translated into action strictly according to that delineated. 2) Stress of inefficiency of organization from which the student doctors suffer can be relieved by management of participation. If they have access to the process of decision-making in general hospital affairs and consequently their understanding and the autonomy of job performance are promoted, such stress will be reduced. 3) To cope with stress of career development from which nurses, medical technicians, administrators, workers in patient affairs suffer, it is necessary to establish whether they have a chance to revive their careers, whether there are any ways of remotivation for less contributive workers, and whether they encourage each other to develope their careers. If they are given a chance to develope their careers, such stress will be relieved. 4) Pharmacists, suffering from stresses of living and personal relations, have strong cohesive power among themselves and organize a well-integrated team; thereby reducing the stress of personal relations and increasing productivity. 5) For administrators and student doctors confined to lesser social supports and for nurses and workers in patient affairs whose recognition of stress and job satisfaction are affected by social supports, emotional and informational supports for job performance help alleviate an individual's mental, and physical stress. 6) In addition to the above-mentioned stress-management methods, if an organizational coping strategy is provided according to the types of stress from the general viewpoint of the whole group of hospital workers, it would be of great help to managing stress. For example, the redesign of jobs, the management of objective, the improvement of working environment, the formation of an autonomous working group and various working plans can be set up for those who suffer from stress related to inappropriate role, while career counseling and development of career process can be provided for those dissatisfied with career development. Participation in the process of decision-making and the restructuring of the organization are needed for those who suffer from stress of malfunctioning organization, whereas creation of a supportive organizational atmosphere is desired for those who feel stressed due to personal relations. As well, such organizational coping strategies. as the increase of welfare facilities, seminars and educational programs and provision of health-promotion facilities can be provided.

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