• 대한수학회보
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• 제52권4호
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• pp.1097-1105
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• 2015

The concept of tensor analogues of right 2-Engel elements in groups were defined and studied by Biddle and Kappe [1] and Moravec [9]. Using the automorphisms of a given group G, we introduce the notion of tensor analogue of 2-auto Engel elements in G and investigate their properties. Also the concept of $2_{\otimes}$-auto Engel groups is introduced and we prove that if G is a $2_{\otimes}$-auto Engel group, then $G{\otimes}$ Aut(G) is abelian. Finally, we construct a non-abelian 2-auto-Engel group G so that its non-abelian tensor product by Aut(G) is abelian.

• 대한수학회논문집
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• 제35권4호
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• pp.1087-1093
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• 2020

The aim of this paper is to show that every Engel quasinormal subgroups of the unit group of a division ring with uncountable center is central.

• 대한수학회보
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• 제53권3호
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• pp.657-665
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• 2016

A general notion of ${\chi}$-transitive groups was introduced by C. Delizia et al. in [6], where ${\chi}$ is a class of groups. In [5], Ciobanu, Fine and Rosenberger studied the relationship among the notions of conjugately separated abelian, commutative transitive and fully residually ${\chi}$-groups. In this article we study the concept of 2-Engel transitive groups and among other results, its relationship with conjugately separated 2-Engel and fully residually ${\chi}$-groups are established. We also introduce the notion of 2-Engelizer of the element x in G and denote the set of all 2-Engelizers in G by $E^2(G)$. Then we construct the possible values of ${\mid}E^2(G){\mid}$.

• 대한가정학회지
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• 제32권2호
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• pp.1-16
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• 1994

This paper analysis the structure of Housing Consumption Expenditure of urban salary and wage-earners' households from 1982 to 1992 by employing Time-series. Data was based on " Annual report on the Family Income and Expenditure Survey" of the National Bureau of Statistic Planning Board, Republic of Korea. Percentile marginal-propensity to consume(MPC) and income elasticity of consumption expenditure are estimated by their socio-economic and demographic variables. The results are as follows: 1. The proportion of the expenditure for furniture and utensils and house mending has increased with the increase of income in urban salary and wage-earners' households, while fuel light and water charges and rents paid has decreased. 2.1) Engel Function by income group; MPC associated with rents paid and fuel light and water charges is higher in the lower income group than in the rest. The income elasticity estimates in rents paid and fuel light and water charges is less than 1 in all group while larger than 1 in furniture and utensils and house mending. 2) Engel Function by occupation of household head; The highest MPC in rents paid is associated with the sales profession. The income elasticity of fuel light and water charge is found be inelastic. The groups other than the sales group show irregular MPC. 3) Engel Function by family size; MPC in house mending and fuel light and water charge is increased while is decreased in rents paid in accordance with family size. The income elasticity of rents paid and fuel light and water charge is less than 1 in all groups while that of house mending and furniture and utensils is larger than 1. 4) Engel Function by age of housegold head; MPC in rents paid is decreased according to the age of housefold head. The income elasticity of rents paid and fuel light and water charge is less than 1 in all group while it is larger than 1.

• 보건의료기술평가
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• 제6권2호
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• pp.142-147
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• 2018

Objectives: The purpose of this study is to evaluate the safety and effectiveness of Robot-Assisted Brain Stereotactic Surgery with a systematic review. Methods: Electronic literature was searched using KoreaMed, Ovid-MEDLINE, Ovid-EMBASE, and Cochrane Library on 6th April 2017. Two authors screened 1218 citations. Duplicated articles of 456 excluded, the remaining 762 articles were reviewed with title and abstract. Results: A total of 8 studies were selected in this review. The device used in all studies was $ROSA^{TM}$. In one cohort study comparing the intervention ($ROSA^{TM}$) with the control (conventional stereotactic surgery), hematoma was reported no significant difference between groups. In six descriptive studies, one study reported hematoma 10% (10/100) and temporary nerve impairment 6% (6/100) using the ROSA; while five descriptive study did not report any complications. In one cohort, the localization precision were 1.2 mm in the intervention group and 1.1 mm in the control group; the localization success rate as 78.2% in the intervention group and 76.2% in the control group in one cohort; and the average time for surgery as 130 min for the intervention group and 352 min for the control group in one cohort. Four studies reported the localization success rate as 100%; two out of three articles reported the overall time for surgery as 56 min and 90 min, while one article reported the time as less than one hour in 50% of patients (50/100); two articles reported in epilepsy patients, the condition after the surgery was Engel level I in 66.2%, 75% patients, Engel level II-III in 25%, 26.5% patients, and Engel level 4 in 7.3% patients. Conclusion: Robot-Assisted Brain Stereotactic Surgery is a safe and accurate technique that can significantly reduce the time for the brain stereotactic surgery. However, further studies are needed to generalize the results.

• 대한수학회보
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• 제51권4호
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• pp.923-931
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• 2014

Let x be an element of a group G and be an automorphism of G. Then for a positive integer n, the autocommutator $[x,_n{\alpha}]$ is defined inductively by $[x,{\alpha}]=x^{-1}x^{\alpha}=x^{-1}{\alpha}(x)$ and $[x,_{n+1}{\alpha}]=[[x,_n{\alpha}],{\alpha}]$. We call the group G to be n-auto-Engel if $[x,_n{\alpha}]=[{\alpha},_nx]=1$ for all $x{\in}G$ and every ${\alpha}{\in}Aut(G)$, where $[{\alpha},x]=[x,{\alpha}]^{-1}$. Also, for any integer $n{\neq}0$, 1, a group G is called an n-auto-Bell group when $[x^n,{\alpha}]=[x,{\alpha}^n]$ for every $x{\in}G$ and each ${\alpha}{\in}Aut(G)$. In this paper, we investigate the properties of such groups and show that if G is an n-auto-Bell group, then the factor group $G/L_3(G)$ has finite exponent dividing 2n(n-1), where $L_3(G)$ is the third term of the upper autocentral series of G. Also, we give some examples and results about n-auto-Bell abelian groups.

• Journal of Korean Neurosurgical Society
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• 제65권3호
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• pp.415-421
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• 2022

Objective : Seizure recurrence after the first-ever seizure in patients with a supratentorial cerebral cavernous malformation (CCM) is almost certain, so the diagnosis and treatment of epilepsy is justified. The optimal method of management of these patients is still a matter of debate. The aim of our study was to identify factors associated with postoperative seizure control and assess the surgical morbidity rate. Methods : We retrospectively analysed 45 consecutive patients with a supratentorial CCM and symptomatic epilepsy in a single centre. Pre- and postoperative epidemiological data, seizure-related patient histories, neuroimaging results, surgery details and outcomes were obtained from hospital medical records. Seizure outcomes were assessed at least 12 months after surgery. Results : Thirty-five patients (77.8%) were seizure free at the long-term follow-up (Engel class I); six (13,3%) had rare, nocturnal seizures (Engel class II); and four (8.9%) showed meaningful improvement (Engel class III). In 15 patients (33%) in the Engel I group; it was possible to discontinue antiepileptic medication. Although there was not statistical significance, our results suggest that patients can benefit from early surgery. No deaths occurred in our study, and mild postoperative neurologic deficits were observed in two patients (4%) at the long-term follow-up. Conclusion : Surgical resection of CCMs should be considered in all patients with a supratentorial malformation and epilepsy due to the favourable surgical results in terms of the epileptic seizure control rate and low postoperative morbidity risk, despite the use of different predictors for the seizure outcome.

• Korean Journal of Radiology
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• 제2권2호
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• pp.63-67
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• 2001

Objective: Atrophy and a high T2 signal of the hippocampus are known to be the principal MR imaging findings of hippocampal sclerosis. The purpose of this study was to determine whether or not individual MRI findings correlate with surgical outcome in patients with this condition. Materials and Methods: Preoperative MR imaging findings in 57 consecutive patients with pathologically-proven hippocampal sclerosis who underwent anterior temporal lobectomy and were followed-up for 24 months or more were retrospectively reviewed, and the results were compared with the postsurgical outcome (Engel classification). The MR images included routine sagittal T1-weighted and axial T2-weighted spin-echo images, and oblique coronal T1-weighted 3D gradient-echo and T2-weighted 2D fast spin-echo images obtained on either a 1.5 T or 1.0 T unit. The images were visually evaluated by two neuroradiologists blinded to the outcome; their focus was the presence or absence of atrophy and a high T2 hippocampal signal. Results: Hippocampal atrophy was seen in 96% of cases (55/57) [100% (53/53) of the good outcome group (Engel class I and II), and 50% (2/4) of the poor outcome group (class III and IV)]. A high T2 hippocampal signal was seen in 61% of cases (35/57) [62% (33/53) of the good outcome group and 50% (2/4) of the poor outcome group]. All 35 patients with a high T2 signal had hippocampal atrophy. 'Normal' hippocampus, as revealed by MR imaging, occurred in 4% of patients (2/57), both of whom showed a poor outcome (Engel class III). The presence or absence of hippocampal atrophy correlated well with surgical outcome (p<0.01). High T2 signal intensity did not, however, significantly correlate with surgical outcome (p>0.05). Conclusion: Compared with a high T2 hippocampal signal, hippocampal atrophy is more common and correlates better with surgical outcome. For the prediction of this, it thus appears to be the more useful indicator.

• Journal of Korean Neurosurgical Society
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• 제29권12호
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• pp.1650-1656
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• 2000

Objective : Little consensus exists concerning which temporal lobe structures need to be resected or how much resection should be done during hippocampal resection. The purpose of this study is to identify whether the extent of hippocampal resection influences seizure after anterior temporal lobectomy. Materials and Methods : The extent of hippocampal resection was assessed in 96 patients who underwent temporal lobectomy for medically intractable complex partial seizures originating from a unilateral seizure focus in the anteromesial temporal lobe. Patients who had structural lesion were excluded from the study. Postoperative magnetic resonance imaging in the coronal and saggital planes were used to quantify the extent of the hippocampal and lateral cortical resection. The patients were divided into two groups. Patients who underwent hippocampal resection to the level of the cerebral peduncle were included in the partial resection group, and those who had resection to the level of the colliculus were assigned to total resection group. Seizure outcomes were defined according to the Engel classification and compared between the two groups. Neuropsychologic outcomes in the selected cases were reviewed. Results : The over-all seizure-free outcome(Engel classification 1) was accomplished in 75%(72/96) of the patients (mean duration of follow-up, 36.8 months). The total hippocampectomy group had a statistically superior seizure outcome than the partial hippocampectomy group(87.3% versus 58.5% seizure-free, p-value=0.001). Also, younger patients had a more favorable outcome. Other variables such as laterality, the extent of lateral cortical resection, age at onset and gender were not significant. The pre- and postoperative memory functions were evaluated in 24 patients. A worse postoperative memory outcome was associated with partial hippocampectomy. However this was not acceptable due to a former bias. Conclusion : The result of this study conforms that aggressive hippocampectomy resulted in a better seizure outcome.

• 한국의류학회지
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• 제13권3호
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• pp.223-241
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• 1989

As a preliminary work for the clothing conformity study, Its theoretical backgrounds were reviewed. In the view of convertibility into clothing conformity, two prevailing conformity types were studied. One is normative-social influence and informational-social influence classified by Deutsch and Gerald. And the other is Kelman's classification which includes compliance, identification and internalization. Reference group, as an object of conformity, was studied. In addition to Engel and Blackwell' s and Assael's classification, the reference groups which were revealed in the studies of consumer behavior and clothing behavior were reviewed. The factors were reviewed which influence conformity and clothing conformity. They were product factor, group factor, situational factor and individual factor.