• Title/Summary/Keyword: 시험센터

Search Result 927, Processing Time 0.034 seconds

Dynamic Analysis of Tie-rod-fastened Rotor Considering Elastoplastic Deformation (탄소성 변형을 고려한 타이로드 고정 회전체의 동역학 해석)

  • Dongchan Seo;Kyung-Heui Kim;Dohoon Lee;Bora Lee;Junho Suh
    • Tribology and Lubricants
    • /
    • v.40 no.1
    • /
    • pp.8-16
    • /
    • 2024
  • This study conducts numerical modeling and eigen-analysis of a rod-fastened rotor, which is mainly used in aircraft gas turbine engines in which multiple disks are in contact through curvic coupling. Nayak's theory is adopted to calculate surface parameters measured from the tooth profile of the curvic coupling gear. Surface parameters are important design parameters for predicting the stiffness between contact surfaces. Based on the calculated surface parameters, elastoplastic contact analysis is performed according to the interference between two surfaces based on the Greenwood-Williamson model. The equivalent bending stiffness is predicted based on the shape and elastoplastic contact stiffness of the curvic coupling. An equation of motion of the rod-fastened rotor, including the bending stiffness of the curvic coupling, is developed. Methods for applying the bending stiffness of a curvic coupling to the equation of motion and for modeling the equation of motion of a rotor that includes both inner and outer rotors are introduced. Rotordynamic analysis is performed through one-dimensional finite element analysis, and each element is modeled based on Timoshenko beam theory. Changes in bending stiffness and the resultant critical speed change in accordance with the rod fastening force are predicted, and the corresponding mode shapes are analyzed.

Effect of Non-Plastic Fines Content on the Pore Pressure Generation of Sand-Silt Mixture Under Strain-Controlled CDSS Test (변형률 제어 반복직접단순전단시험에서 세립분이 모래-실트 혼합토의 간극수압에 미치는 영향)

  • Tran, Dong-Kiem-Lam;Park, Sung-Sik;Nguyen, Tan-No;Park, Jae-Hyun;Sung, Hee-Young;Son, Jun-Hyeok;Hwang, Keum-Bee
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.28 no.1
    • /
    • pp.33-39
    • /
    • 2024
  • Understanding the behavior of soil under cyclic loading conditions is essential for assessing its response to seismic events and potential liquefaction. This study investigates the effect of non-plastic fines content (FC) on excess pore pressure generation in medium-density sand-silt mixtures subjected to strain-controlled cyclic direct simple shear (CDSS) tests. The investigation is conducted by analyzing excess pore pressure (EPP) ratios and the number of cycles to liquefaction (Ncyc-liq) under varying shear strain levels and FC values. The study uses Jumunjin sand and silica silt with FC values ranging from 0% to 40% and shear strain levels of 0.1%, 0.2%, 0.5%, and 1.0%. The findings indicate that the EPP ratio increases rapidly during loading cycles, with higher shear strain levels generating more EPP and requiring fewer cycles to reach liquefaction. At 1.0% and 0.5% shear strain levels, FC has a limited effect on Ncyc-liq. However, at a lower shear strain level of 0.2%, increasing FC from 0 to 10% reduces Ncyc-liq from 42 to 27, and as FC increases further, Ncyc-liq also increases. In summary, this study provides valuable insights into the behavior of soil under cyclic loading conditions. It highlights the significance of shear strain levels and FC values in excess pore pressure generation and liquefaction susceptibility.

Expanding the Supply of Home Health Nurses : Post-Master's Program and Certification Examination (가정전문간호사 공급 확대를 위한 방안: 석사후과정과 자격시험)

  • Baek, Heechong;Lee, Kayoung;Song, Chong Rye
    • Journal of Home Health Care Nursing
    • /
    • v.31 no.1
    • /
    • pp.5-15
    • /
    • 2024
  • Purpose: The study aim was to examine the home healthcare system and relevant education, as well as the special certification examination, and propose a plan to increase the supply of home health nurses. Methods: A narrative literature review was conducted using data from research articles, Korean and U.S. educational institutes and organizations, Korean national statistical data, government press releases, and related medical legislation. Results: Between 2005 and 2006, 763 home health nurses were certified through the special qualification examination; however, in the 16 years from 2007 to 2023 (after the graduate-level program was established), a total of 555 home health nurses were certified, with an average of approximately 35 per year. Currently, 790 home health nurses are working at 194 medical institutions nationwide. Relatively few institutions exist in rural areas, and the supply of home health nurses is low. Only seven educational institutions offer home health nurse certification programs, with a total of 77 designated students. In contrast to Korea, post-master's certification courses are offered in the U.S.. Conclusion: To expand the supply of home health nurses, we recommend revising the rules for the special qualification examination and introducing a post-master's certification program for home health nurses. Future studies should provide additional education for applicants from other specialties in post-master's certification programs.

Development of Effective Test Method for Positioning Accuracy of Armed Vehicle Inertial Navigation System (기동화력장비 관성항법장치의 효과적인 위치정확도 시험방법 개발)

  • Kim, Sung Hoon;Bae, In Hwa;Kim, Sang Boo
    • Journal of Korean Society for Quality Management
    • /
    • v.51 no.4
    • /
    • pp.619-632
    • /
    • 2023
  • Purpose: The main function of INS (Inertial Navigation System) is to measure the position of an armed vehicle and its performance is confirmed through the positioning accuracy test of Korean Defense Standards (KDS). The current standards, however, do not provide clear test methods and the conditions for performing positioning accuracy tests. Accordingly, the purpose of this study is to develop a new method for positioning accuracy test which would be effective. Methods: In this study, a new INS positioning accuracy test method is suggested based on the analysis of test data collected through a statistical experiment known as central composite design. For the positioning accuracy experiment of K105A1, a self-propelled artillery, two factors of driving velocity and driving distance are considered. Results: Based on the analysis of experimental data, a regression model for the positioning error is fitted and the positioning accuracy test of INS is so developed to maximize the positioning error. The standard proximity rate is used as an additional test criterion to evaluate the performance level of INS. Conclusion: The proposed new positioning accuracy test for INS has the advantage of finding the nonconforming items effectively. It is also expected to be utilized for the other similar INS positioning accuracy tests.

A Study on the Properties of Concrete Substituting Copper Slag for Fine Aggregate (잔골재를 동슬래그로 대체한 콘크리트의 특성 연구)

  • Bae, Ju Seong;Kim, Nam Wook;Ko, Sang Hun
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.11 no.3
    • /
    • pp.151-158
    • /
    • 2007
  • The recent government policy for environment is pursuing for a circular waste control system not only to reduce waste as much as possible but also to vigorously use the already produced waste. Copper slag has a higher fineness modulus and a greater specific gravity than natural aggregate. but when the substitutive ratio of fine aggregate is higher than 30%, material segregation occurs by bleeding. Thus, in this study, the strength and the physical properties were tested for the specimens manufactured by varying the types of admixtures, and the substitutive ratio of copper slag to suppress material segregation occurring due to the bleeding of concrete using copper slag as the substitutive material of fine aggregate and to find the adequate substitutive ratio of copper slag.

A Preliminary Study on the Construction of Clinical Data for Korean Herbal Prescription Recommendations for Anxiety, Depression, Anger, and Insomnia (불안, 우울, 분노 및 불면 증상에 대한 한의학파 처방 추천 임상 데이터 구축을 위한 기초 연구)

  • Dong-Hoon Kang;Ju-Yeon Kim;Ji-Yoon Lee;Je-Hyun Kim;Sangjun Yea;Ho Jang;Sanghun Lee;In Chul Jung
    • Journal of Oriental Neuropsychiatry
    • /
    • v.35 no.3
    • /
    • pp.231-246
    • /
    • 2024
  • Objectives: To build basic clinical data for developing an artificial intelligence algorithm for Korean herbal prescriptions for anxiety, depression, anger, and insomnia. Methods: Subjects were recruited among those who reported mild or more severe symptoms of anxiety, depression, anger, and insomnia (Anxiety: State-Trait Anxiety Inventory≥40, Depression: Beck Depression Inventory≥14, Anger: State-Trait Anxiety Inventory≥16, Insomnia: Insomnia Severity Index≥8). Clinical observation items including basic medical information and symptoms were collected from them. These data were then analyzed by experts in Hyungsang medicine, Sasang constitutional medicine, and Sanghan-Geumgwe medicine. Results and Conclusions: Experts of the three societies presented key clinical data and recommended prescriptions. Results of this study can be used as basic data for developing an artificial intelligence algorithm for Korean herbal prescriptions in the future.

Study on size distribution and characteristics of particulate matter suspension in indoor space depending on relative humidity (상대습도에 따른 비산 미세먼지의 크기 분포 및 특성 분석)

  • Minjeong Kim;Jiwon Park
    • Particle and aerosol research
    • /
    • v.20 no.2
    • /
    • pp.25-33
    • /
    • 2024
  • Suspension of particulate matter (PM) in indoor spaces, which increases risk of negative impact on occupants' health from exposure to PM, is influenced by humidity level in the indoor environment. The goal of this study is to investigate the property of size-resolved PM suspension in accordance with the relative humidity through simulation chamber experiments which reflect the indoor environmental characteristics. The relative humidity of simulation chamber is adjusted to 35%, 55% and 75% by placing it inside a real-size environmental chamber which allows artificial control of climatic conditions (e.g., temperature, humidity). At the respective humidity conditions, PM suspension concentration caused by occupant walking is analyzed by particle size (0.5-0.8, 0.8-1.0, 1.0-2.5, 2.5-3.5, 3.5-4.5, 4.5-5.5, 5.5-8.0, and 8.0-10 ㎛). Irrespective of the particle size, the suspension concentration reveals a decreasing tendency as the relative humidity increases. Furthermore, a one-way analysis of variance (one-way ANOVA) test statistically verifies that the suspension concentration has a significant difference depending on the indoor relative humidity level. In addition, as the relative humidity increases, a proportion of the suspended particles with 0.5-2.5 ㎛ diameter decreases, while that with 2.5-3.5 ㎛ diameter increases. The reason is considered that the humidity has an effect on adhesion and coagulation forces of the particles.

A Fundamental Study on Damage Assessment of the 30-Inch Gas Pipeline (30인치 가스 파이프라인 손상평가에 관한 기초 연구)

  • Mutiara Setyaning Dwityas;Chunsik Shim;Kangho Kim;Deokyeon Lee;Daseul Jeong;Youngpyo Kim;Yun-Chan Jang;Byeonghwa Kim;Sungguk Wi
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.61 no.5
    • /
    • pp.378-388
    • /
    • 2024
  • Oil and gas contribute significantly to achieving the growing demand for energy, which is rising in parallel with population growth. The pipeline system is the main transport system used in the distribution of oil and gas because the pipeline system is considered the most effective and efficient system. The distribution system for gas and oil must guarantee security and safety. Analyzing the pipeline is necessary to ensure distribution security and safety. In this study, a finite element analysis of the gas pipeline specimen was conducted. This analysis is carried out in two stages, first structural analysis and continued with damage analysis, where the damage used is a dent. In the dent analysis, environmental conditions are applied, namely non-pressure, pressure, and full pressure. Then assessed all the results of the analysis of each stage, the assessment was carried out by verifying the results of the analysis with the applicable standard rules. So that the characteristics of the pipeline can be recognized and work accidents caused by operating pipeline failure can be avoided.

A New Auricleless Barley Cultivar "Dami" for Whole Crop Forage (밀식적응 양질 다수성 무엽이 청보리 품종 "다미")

  • Park, Tae-Il;Seo, Jae-Hwan;Han, Ouk-Kyu;Park, Ki-Hun;Choi, Jae-Seong;Kim, Jung-Gon;Park, Jong-Chul;Kim, Hong-Sik;Heo, Hwa-Young;Baek, Seong-Bum;Kwon, Young-Up;Park, Hyoung-Ho;Kang, Moon-Seok;Park, Kwang-Geun;Suh, Sae-Jung
    • Korean Journal of Breeding Science
    • /
    • v.41 no.3
    • /
    • pp.349-353
    • /
    • 2009
  • We developed a new barley cultivar "Dami" (Hordeum vulgare L.) with the auricleless gene lig (al, li, aur-a). The characteristic of auricleless is a spontaneous mutant type which has known as a monogenic recessive gene. The plant with the gene has erect leaf blades because of no auricle. The cultivar was derived from a cross between 'BGS60' and 'Kangbori'. 'BGS60' has the auricleless gene (li), while 'Kangbori' showed a high biomass with winter hardiness and resistance to BaYMV (Barley Yellow Mosaic Virus). Subsequent generations were handled by the bulk method in a pedigree selection program. A promising line showed both high yield and lodging resistance in the yield trials at Iksan in 2003 to 2004, and designated as Iksan414. The line was subsequently evaluated for winter hardiness, earliness, and yield in the seven locations around Korea for three years from 2005 to 2007 and was designated as "Dami" and released. It has the growth habit of III, erect plant type, green leaf and stem similar to the check cultivar 'Sunwoo' Its heading date was April 30, and maturing date May 31 in paddy field conditions, which were similar to those of 'Sunwoo' respectively. The cultivar Dami was 97 cm in culm length, had 643 spikes per $m^2$ and higher leaf dry weight, and better adaptability to dense planting, winter hardiness, and resistance to BaYMV than the check cultivar did. The average forage yield of "Dami" was about 12 ton $ha^{-1}$ in dry matter (33 ton $ha^{-1}$ in fresh matter) in paddy field. "Dami" also showed 7.5% of crude protein content, 28.5% of ADF (Acid Detergent Fiber), 50.1% of NDF (Neutral Detergent Fiber), and 66.4% of TDN (Total Digestible Nutrients), including higher grade of silage quality for whole crop barley. This cultivar would be suitable for the area where the daily minimum temperature of January is above $-8^{\circ}C$ in Korean peninsula.

Changes in Agricultural Extension Services in Korea (한국농촌지도사업(韓國農村指導事業)의 변동(變動))

  • Fujita, Yasuki;Lee, Yong-Hwan;Kim, Sung-Soo
    • Journal of Agricultural Extension & Community Development
    • /
    • v.7 no.1
    • /
    • pp.155-166
    • /
    • 2000
  • When the marcher visited Korea in fall 1994, he was shocked to see high rise apartment buildings around the capitol region including Seoul and Suwon, resulting from rising demand of housing because of urban migration followed by second and third industrial development. After 6 years in March 2000, the researcher witnessed more apartment buildings and vinyl house complexes, one of the evidences of continued economic progress in Korea. Korea had to receive the rescue finance from International Monetary Fund (IMF) because of financial crisis in 1997. However, the sign of recovery was seen in a year, and the growth rate of Gross Domestic Products (GDP) in 1999 recorded as high as 10.7 percent. During this period, the Korean government has been working on restructuring of banks, enterprises, labour and public sectors. The major directions of government were; localization, reducing administrative manpower, limiting agricultural budgets, privatization of public enterprises, integration of agricultural organization, and easing of various regulations. Thus, the power of central government shifted to local government resulting in a power increase for city mayors and county chiefs. Agricultural extension services was one of targets of government restructuring, transferred to local governments from central government. At the same time, the number of extension offices was reduced by 64 percent, extension personnel reduced by 24 percent, and extension budgets reduced. During the process of restructuring, the basic direction of extension services was set by central Rural Development Administration Personnel management, technology development and supports were transferred to provincial Rural Development Administrations, and operational responsibilities transferred to city/county governments. Agricultural extension services at the local levels changed the name to Agricultural Technology Extension Center, established under jurisdiction of city mayor or county chief. The function of technology development works were added, at the same time reducing the number of educators for agriculture and rural life. As a result of observations of rural areas and agricultural extension services at various levels, functional responsibilities of extension were not well recognized throughout the central, provincial, and local levels. Central agricultural extension services should be more concerned about effective rural development by monitoring provincial and local level extension activities more throughly. At county level extension services, it may be desirable to add a research function to reflect local agricultural technological needs. Sometimes, adding administrative tasks for extension educators may be helpful far farmers. However, tasks such as inspection and investigation should be avoided, since it may hinder the effectiveness of extension educational activities. It appeared that major contents of the agricultural extension service in Korea were focused on saving agricultural materials, developing new agricultural technology, enhancing agricultural export, increasing production and establishing market oriented farming. However these kinds of efforts may lead to non-sustainable agriculture. It would be better to put more emphasis on sustainable agriculture in the future. Agricultural extension methods in Korea may be better classified into two approaches or functions; consultation function for advanced farmers and technology transfer or educational function for small farmers. Advanced farmers were more interested in technology and management information, while small farmers were more concerned about information for farm management directions and timely diffusion of agricultural technology information. Agricultural extension service should put more emphasis on small farmer groups and active participation of farmers in these groups. Providing information and moderate advice in selecting alternatives should be the major activities for consultation for advanced farmers, while problem solving processes may be the major educational function for small farmers. Systems such as internet and e-mail should be utilized for functions of information exchange. These activities may not be an easy task for decreased numbers of extension educators along with increased administrative tasks. It may be difficult to practice a one-to-one approach However group guidance may improve the task to a certain degree.

  • PDF