• Journal of the Korea Safety Management & Science
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• v.19 no.3
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• pp.89-95
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• 2017

This paper presents another maintenance policy for a group of units under finite operating horizon. A group of identical units are subject to random failures. Group maintenances are performed to all units together at specified intervals, and the failed units during operation are remained idle until the next group maintenance set-up. Unlike the traditional assumption of infinite operating horizon, we adopt the assumption of the finite operating horizon which reflect the rapid industrial advance and short life cycle of modern times. The units are under operation until the end of the operating horizon. Further, the operation of units are extended to the first group maintenance time after the end of the horizon. The total cost under the proposed maintenance policy is derived. The optimal group maintenance interval and the expected number of group maintenances during the horizon are found. It is shown that the proposed policy is better than the classical group maintenance policy in terms of total cost over the operating horizon. Numerical examples are presented for illustrations.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.2
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• pp.33-41
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• 2019

The purpose of this study is to provide a basic data for energy efficient apartment designs by analyzing electricity and gas usage according to horizontal locations of dwelling units in apartment buildings. The data for this research are collected from J-apartment complex, located at 'Wolbae' district in Daegu City. The data are sorted into several groups according to inner and outer locations, East-West locations, and the size of units. By the performance efficiency analysis, the study derives the result as follows: 1) generally inner units are more efficient than outer units. 2) West units are more efficient than East units. 3) The group that is most efficient in overall energy consumption is West-inner units (Group-D) and the least efficient group is East-outer units (Group-A1). 4) However, as units are getting bigger, inner units consumes more energy than outer units because of the gas usage patterns. The study also established cost analysis that shows the cost differences of usages for 30, 40, 50 years between each group. The result says Inner-outer location with East-West location affects a significant amount of the management costs. In terms of economic and social life of an apartment building, energy design standards need to be tuned and make the least efficient units perform as efficient as the most efficient units to optimize the social life of an apartment building.

• Journal of Korean Home Economics Education Association
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• v.19 no.3
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• pp.91-106
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• 2007

The purpose of this study was to provide the information for the development of gender-equality oriented content of Technology Home Economics subject. For this purpose, a total of 404 male and female middle high school students in Chuncheon city were sampled and asked to estimate the degree of practical use and preference for the 47 units of Technology Home Economics subject. Results were summarized as following : 1. The 47 units were classified into 4 groups on the basis of similarity in the degree of practical use and preference: 23 units estimated as 'better than average' by male and female students were classified into group 1; 4 units estimated as 'better than average' by female students but as 'less than average' by male students were classified into group 2; 10 units estimated as 'less than average' by male and female students were classified into group. 3; 10 units estimated as 'far less than average' by male and female students were classified into group 4. Most of the units in Home Economics area were classified Into group 1 or 2, but most of the units in Technology area were classified into group 3 or 4. 2. Gender difference was confirmed between male and female students' estimation of the degree of practical use and preference for the 47 units. In about three-quaters of the units in Home Economics area, female students' estimation of the degree of practical use and preference was higher than male students' estimation. In about half of the units in Technology area, male students' estimation of the degree of practical use and preference was higher than female students' estimation. However, possibility was detected in several units of Technology Home Economics subject that gender difference could be decreased.

• Journal of the Korean Society for Library and Information Science
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• v.24
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• pp.73-112
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• 1993

The purpose of this study is to identify what are the common characteristics which enable the information management offices of research institutes to provide information services with their companies in effective ways, and furthur, in other to clarify what factors helf the improvement of effectiveness of information services. I have made on-the-spot investigations for the confirmation of present conditions of information service units of research institutes, their statistic data, and their managerial state. I have restricted my research to 36 information service units, as research targets, which are located in Changwon, Choongchong, and Kyongin areas as the reason mentioned in the introduction, and from their research data they keep, I have classified the top 10 information service units as Group A which show the most frequent use or application frequency of research data per a researcher, where as the lowerest 10 information service units are classified as Group B by the same evaluation of application frequency of their data. Then, the result of the comparision between Group A which provide high information services in effective ways and Group B which provide low information services with poor management leads me to identify the following characteristics in terms of the analyses of utilization of the data they process: 1. Those information service units in Group A have more volumes of books and information data, and annual increasing rates of books and informations are higher than those of Group B. 2. The regulations of book circulation in Group A are prescribed for the benefits of users, and if a long-term loan is not permitted, they are allowed to borrow more books at a time than in Group B. 3. The proportion of librarians to researchers is high, the librarians' career is long and their professional education background (the rate of librarians who majored in library science and information) is high In Group A. 4. Most of the directors of information service units are those who majored library science and information, and for the most part, librarians are promoted to the directors of information service units in Group A. 5. The information service units are managed directly under the directors of research institutes in their organization in Group A. 6. The information service units offer an education for information utilization to researchers as one of their managerial programs, and the contents of education are diverse, rich and informative in Group A. 7. The kinds of informations are various in Group A such as, SDI, prompt reports of contents of new informations, circulation of newly published publications, translation service, information analyses, critical reviews, etc. 8. The information service units in Group A have joined various cooperative systems which are aimed at cooperation, co-ownership of resources and informations. These findings lead me to argue that the hypothesis suggested in the introduction of this thesis has been proved without exception.

• Journal of the Korean Mathematical Society
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• v.46 no.3
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• pp.475-491
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• 2009

In [2], we identified the group of units of finite local rings $\mathbb{Z}_4[X]$/($X^k+2X^a$, $2X^r$) with certain restrictions on a. In this paper we find direct sum decomposition of the group of units of such rings without restrictions on a into cyclic subgroups by finding their generators. And further generalization is considered.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.174-184
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• 2006

Purpose: Current trend in implant dentistry is changing from external connection to internal connection. To evaluate the splinting of external and internal connection implant on screw loosening, 2-units prosthesis was fabricated with BioPlant $System^(R)$ of external connection type and Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. Material and Method: Experimental group is classified into three groups. 1) $G_1-EE$: 2-units prosthesis was fabricated with two Bioplant $System^(R)$ of external connection type. 2) $G_1-EI$: 2-units prosthesis was fabricated with one BioPlant $System^(R)$ of external connection type and one Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. 3) $G_1-II$: 2-units prosthesis was fabricated with two Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. In fabricating 2-units prosthesis, two hexed abutments are recommended when two implants are installed parallel, otherwise one hexed abutment is used on major occlusal force area and one nonhexed abutment is used on the other area. Since it is rare to find two implants being parallel, it is hard to fabricate prosthesis with passive adaptation using two hexed abutments. It is much more difficult to acquire passive adaptation when using hex abutment compared to nonhex abutment. To evaluate the influence of hexed and nonhexed abutment on screw loosening, 2-units prosthesis was fabricated with hexed and nonhexed abutment. Experimental group is classified into three groups. 1) $G_2-HH$: 2-units prosthesis was fabricated with two hexed abutments. 2) $G_2-HN$: 2-units prosthesis was fabricated with one hexed abutment and one nonhexed abutment. 3) $G_2-NN$: 2-units prosthesis was fabricated with two nonhexed abutments. Result: The results of comparing the detorque value after loading on a each prosthesis periodically are as follows. 1. In splinting group of external and internal connection implant, $G_1-II$ group demonstrated the biggest detorque value, followed by $G_1-EI$ group and $G_1-EE$ group. 2. There is no notable significance between external connection implant of $G_1-EI$ group and $G_1-EE$ group and also no significance between internal connection implant of $G_1-EI$ group and $G_1-II$ group. 3. $G_2-HH$ group showed higher detorque value than $G_2-HN\;and\;G_2-NN$ group. From the results, we can concluded that using both external connection and internal connection implant together is clinically acceptable and in order to acquire a good passive adaptation in fabricating 2-units implant prosthesis we can use two nonhexed abutments.

• Korean Journal of Mathematics
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• v.21 no.3
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• pp.331-344
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• 2013

In the present article, we describe specific elements in a motivic cohomology group $H^1_{\mathcal{M}}(Spec\mathbb{Q}({\zeta}_l),\;\mathbb{Z}(2))$ of cyclotomic fields, which generate a subgroup of finite index for an odd prime $l$. As $H^1_{\mathcal{M}}(Spec\mathbb{Q}({\zeta}_l),\;\mathbb{Z}(1))$ is identified with the group of units in the ring of integers in $\mathbb{Q}({\zeta}_l)$ and cyclotomic units generate a subgroup of finite index, these elements play similar roles in the motivic cohomology group.

• PNF and Movement
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• v.18 no.1
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• pp.55-64
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• 2020

Purpose: The purpose of this study was to compare the strength and walking ability of chronic stroke patients following either proprioceptive neuromuscular facilitation (PNF) pattern training with pressure biofeedback units (feedback group) or PNF pattern training without pressure biofeedback units (control group). Methods: Eighteen participants with chronic stroke were recruited from a rehabilitation hospital. They were divided into two groups: a feedback group (n = 8) and a control group (n = 10). They all received 30 minutes of neurodevelopmental therapy and PNF training for 15 minutes five times a week for three weeks. Muscle strength and spatiotemporal gait parameters were measured. Muscle strength was measured by hand-held dynamometer; gait parameters were measured by the Biodex Gait trainer treadmill system. Results: After the training periods, the feedback group showed a significant improvement in hip abductor muscle strength, hip extensor muscle strength, step length of the unaffected limb, and step time of the affected limb (p<0.05). Conclusion: The results of this study showed that proprioceptive neuromuscular facilitation pattern training with pressure biofeedback units was more effective in improving hip muscle strength and walking ability than the proprioceptive neuromuscular facilitation pattern training without pressure biofeedback units. Therefore, to strengthen hip muscles and improve the walking ability of stroke patients, using pressure biofeedback units to improve trunk stability should be considered.

• Korean Journal of Mathematics
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• v.17 no.2
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• pp.189-196
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• 2009

Let D be an integral domain, and let U be a group of units of D. Let $D^*=D-\{0\}$ and ${\Gamma}=D^*/U$ be the commutative cancellative semigroup under aU+bU=abU. We prove that $Cl(D)=Cl({\Gamma})$ and that D is a PvMD (resp., GCD-domain, Mori domain, Krull domain, factorial domain) if and only if ${\Gamma}$ is a PvMS(resp., GCD-semigroup, Mori semigroup, Krull semigroup, factorial semigroup). Let U=U(D) be the group of units of D. We also show that if D is integrally closed, then $D[{\Gamma}]$, the semigroup ring of ${\Gamma}$ over D, is an integrally closed domain with $Cl(D[{\Gamma}])=Cl(D){\oplus}Cl(D)$; hence D is a PvMD (resp., GCD-domain, Krull domain, factorial domain) if and only if $D[{\Gamma}]$ is.

• Communications of the Korean Mathematical Society
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• v.12 no.4
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• pp.855-864
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• 1997

Let K be a algebraically closed field of characteristic 0 and G a cyclic group of order n. We find the units and idempotent elements of the group ring KG by using the basic group table matrix of G.