• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.27 no.1
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• pp.75-86
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• 2023

The angle of attack is highly sensitive to pitch point in the airfoil shape and the decline of pitch point value induces smaller angle of attack, which implies that airfoil profile possessing closer pitch point to the airfoil tip reacts more sensitively to upcoming wind. The method of conformal transformation functions is employed for airfoil profiles and airfoil surfaces are expressed with a trigonometric series form. Attack angle and ideal lift coefficient distributions are investigated for various airfoil profiles in wind turbine blade regarding conformal transformation and pitch point. The conformed angle function representing the surface angle of airfoil shape generates various attack angle distributions depending on the choice of surface angle function. Moreover, ideal attack angle and ideal lift coefficient are susceptible to the choice of airfoil profiles and uniform loading area. High ideal attack angle signifies high pliability to upcoming wind, and high ideal lift coefficient involves high possibility to generate larger electric energy. According to results obtained pitch point, airfoil shape, uniform loading area, and the conformed airfoil surface angle function are crucial factors in the determination of angle of attack.

• Journal of Korean Academy of Nursing Administration
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• v.9 no.2
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• pp.251-264
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• 2003

Purpose : The expectations are defined as desired expectations in initial SERVQUAL scale(1985, 1988), but in modified SERVQUAL scale(1991), are defined as a feasible ideal point expectations. In assessment of nursing service quality by SERVQUAL scale, the definitions of expectations is important problem. The purpose of this study was to compare the feasible ideal point expectations with the desired expectations in assessment of nursing service quality using SERVQUAL scale. Methods : The subjects were 256 inpatients at 4 general hospitals in Jeju-do(123 for feasible ideal point and 133 for desired). The data were collected by two types of self-reporting questionnaires to measure the feasible ideal point and desired expectations. For data analysis, t-test, multiple regression, and comparative analysis of multiple Rs via Fishers Z transformation. Results : Compared with the SERVQUAL scores, the feasible ideal point expectations better explained the variations of the overall consumer satisfaction($R^2$=O.33) than the desired($R^2$=O.25). Conclusion : The feasible ideal point expectations were more suitable to the assessment of nursing service quality using SERVQUAL scale. It will be need to explore the conceptual definitions of expectations using SERVQUAL scale in different settings. Also, further study needs to be conducted to compare alternative service quality measurement scales.

• Health Policy and Management
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• v.10 no.3
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• pp.155-168
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• 2000

The SERVQUAL scale is based on the gap theory, which indicates the difference between consumers' expectations and their actual performance. In SERVQUAL scale, the expectations are defined as a "feasible ideal point"(ex, An Excellent hospital has up-to-date equipment). But empirical research identified important problems concerning the conceptual definitions of expectations. They suggests the usage of "desired expectations". Desired expectations are defined as the level at which the consumer predict the service that the organization they visited will perform(ex, $\bigcirc\bigcirc$ hospital has up-to-date equipment). The purpose of this study was to compare the feasible ideal point expectations with desired expectations in assessment of consumer expectations using SERVQUAL scale. We developed two types of questionnaires : (1) to measure feasible ideal point expectations, (2) to measure desired expections. Questionnaire were distributed to ambulatory patients who used the medical service. Total 329 patients participated the hosiptal satisfaction questionnaire(167 for feasible ideal point expectations, 162 for desired expectations). The major finding is as follows: (1) the SERVQUAL scale which was computed by the feasible ideal point showed the higher explanatory power in consumer satisfaction ($R^2$=0.26) than the other identified alternatives(desired expectation, $R^2$=0.11) The results of a study suggests that the feasible ideal point were more conceptually suitable to assess of consumer satisfaction using SERVQUAL scale.SERVQUAL scale.

• Journal of Korean Neurosurgical Society
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• v.63 no.5
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• pp.614-622
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• 2020

Objective : The method of approach during transforaminal endoscopic lumbar discectomy (TELD) has been the subject of repeated study. However, the ideal entry point during TELD has not been studied in detail. Therefore, this study investigated the ideal entry point for avoiding complications using computed tomography (CT) scans obtained from patients in the prone position. Methods : Using CT scans obtained from patients in the prone position, we checked for retroperitoneal or visceral violations and measured the angles of approach with five conventional approach lines drawn on axial CT scans at each disc space level (L2-3, L3-4, and L4-5). We also determined the ideal entry point distance and approach angles for avoiding retroperitoneal or visceral violations. Correlation analysis was performed to identify the patient characteristics related to the ideal entry point properties. Results : We found that the far lateral approach at the L2-3 level resulted in high rates of visceral violation. However, rates of visceral violation at the L3-4 and L4-5 levels were remarkably low or absent. The ideal angles of approach decreased moving caudally along the spine, and the ideal entry point distances increased moving caudally along the spine. Weight, body mass index (BMI), and the depth of the posterior vertebral line from the skin were positively associated with the distance of the ideal entry point from the midline. Conclusion : We reviewed the risk of the extreme lateral approach by analyzing rates of retroperitoneal and visceral violations during well-known methods of approach. We suggested an ideal entry point at each level of the lumbar spine and found a positive correlation between the distance of the entry point to the midline and patient characteristics such as BMI, weight, and the depth of the posterior vertebral line from the skin.

• Communications of the Korean Mathematical Society
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• v.13 no.1
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• pp.95-107
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• 1998

In this paper we prove the Hopf-Rinow theorem for CAT(0) spaces and show that the ideal boundaries of complete CAT(0) manifolds of dimension 2 or 3 with some additional conditions are homeomorphic to the circle or 2-sphere by the characterization of the local shadows around the branch points.

• Bulletin of the Korean Mathematical Society
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• v.43 no.3
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• pp.559-573
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• 2006

In this Paper three different types of fuzzy Prime ideals are introduced. Condition is obtained for a fuzzy 2-prime ideal will have two elements in its range. It has been shown that A is fuzzy 2-prime ideal of the semiring R if and only if 1-A is a fuzzy $m_2-system$ in R.

• Honam Mathematical Journal
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• v.27 no.4
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• pp.525-541
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• 2005

We give the characterization of an intuitionistic fuzzy ideal[resp. intuitionistic fuzzy left ideal, an intuitionistic fuzzy right ideal and an intuitionistic fuzzy bi-ideal] generated by an intuitionistic fuzzy set in a semigroup without any condition. And we prove that every intuitionistic fuzzy ideal of a semigroup S is the union of a family of intuitionistic fuzzy principle ideals of S. Finally, we investigate the intuitionistic fuzzy ideal generated by an intuitionistic fuzzy set in $S^1$.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1308-1316
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• 2017

The distributed maximum power point tracking (DMPPT) concept is widely adopted in photovoltaic systems to avoid mismatch loss. However, the high cost and complexity of DMPPT hinder its further promotion in practice. Based on the concept of DMPPT, this paper presents an integrated submodule level half-bridge stack structure along with an optimal current point tracking (OCPT) control algorithm. In this full power processing integrated solution, the number of power switches and passive components is greatly reduced. On the other hand, only one current sensor and its related AD unit are needed to perform the ideal maximum power generation for all of the PV submodules in any irradiance case. The proposal can totally eliminate different small-scaled mismatch effects in real-word condition and the true maximum power point of each PV submodule can be achieved. As a result, the ideal maximum power output of the whole PV system can be achieved. Compared with current solutions, the proposal further develops the integration level of submodule DMPPT solutions with a lower cost and a smaller size. Moreover, the individual MPPT tracking for all of the submodules are guaranteed.

• The Pure and Applied Mathematics
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• v.11 no.4
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• pp.309-321
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• 2004

For a complete open Riemannian manifold, the ideal boundary consists of points at infinity. The so-called Busemann-functions play the role of distance functions for points at infinity. We study the similarity and difference between Busemann-functions and ordinary distance functions.

• Communications of the Korean Mathematical Society
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• v.33 no.2
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• pp.671-676
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• 2018

In this paper we prove that the gradient ideal of a Morse polynomial is radical. This gives a generic class of polynomials whose gradient ideals are radical. As a consequence we reclaim a previous result that the unconstrained polynomial optimization problem for Morse polynomials has a finite convergence.