• 한국자기공명학회논문지
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• 제12권2호
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• pp.103-110
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• 2008

Spin Hamiltonian for the paramagnetic center with a three-fold symmetry and high spin ($S{\geq}2$) multiplicity should contain the fourth order zero-field splitting (ZFS) terms. Electron magnetic resonance transition lines of the center with S = 5/2 are expected to split in a pair when the magnetic field is applied off the principal axes of ZFS, while they are superimposed when the magnetic field is applied parallel to the principal axes of ZFS. In this study we report that the transition lines of $Mn^{2+}$ centers at the three-fold symmetric sites in $LiNbO_3$, chemically equivalent but physically different, split in two due to the nonzero fourth order ZFS term.

• 대한수학회지
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• 제51권5호
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• pp.1045-1073
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• 2014

The study of the identities of symmetry for the Bernoulli polynomials arises from the study of Gauss's multiplication formula for the gamma function. There are many works in this direction. In the sense of p-adic analysis, the q-Bernoulli polynomials are natural extensions of the Bernoulli and Apostol-Bernoulli polynomials (see the introduction of this paper). By using the N-fold iterated Volkenborn integral, we derive serval identities of symmetry related to the q-extension power sums and the higher order q-Bernoulli polynomials. Many previous results are special cases of the results presented in this paper, including Tuenter's classical results on the symmetry relation between the power sum polynomials and the Bernoulli numbers in [A symmetry of power sum polynomials and Bernoulli numbers, Amer. Math. Monthly 108 (2001), no. 3, 258-261] and D. S. Kim's eight basic identities of symmetry in three variables related to the q-analogue power sums and the q-Bernoulli polynomials in [Identities of symmetry for q-Bernoulli polynomials, Comput. Math. Appl. 60 (2010), no. 8, 2350-2359].

• Applied Microscopy
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• 제40권1호
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• pp.21-28
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• 2010

단층 및 복층의 그래핀에 대한 원자분해 투과전자현미경 영상 시뮬레이션 연구에서, 통상의 Boch-wave 방법에 의한 영상이론식들이 고 준위 Laue 영역의 역 격자 회절을 적절히 포함 했을 때 시뮬레이션에 잘 적용될 수 있음을 보여 주었다. 적절한 조건에서 복층 그래핀의 시뮬레이션 영상들은 육방정계의 대칭성 보다는 삼방정계의 대칭성을 보여 주었다. 이 결과는 복층 그래핀이 3차원 공간에서 [0001] 축 방향 회전에 대해 갖는 삼방정계의 격자 대칭성이 영상에 구현되는 것으로 이해될 수 있다. 단층 그래핀에 대해서는, 관측 위상영상이 삼방정계의 대칭성을 보여주는 현상들이 특히 주목되었다. 이 현상은 그래핀 표면에 전자 밀도의 재 배치에 의한 것으로 설명되었다. 그리고 그래핀의 전자 재 배치를 반영하는, 다만 2번째 Laue 준위 영역의 회절 빔까지만 포함하면 관측 영상과 일치하는 시뮬레이션 위상 영상이 얻어졌다.

• Archives of Plastic Surgery
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• 제41권1호
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• pp.57-62
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• 2014

Background Achieving symmetry is a key goal in breast reconstruction. Anatomically shaped tabbed expanders are a new tool in the armamentarium of the breast reconstruction surgeon. Suture tabs allow for full control over the expander position and thus inframammary fold position, and, in theory, tabbed expanders mitigate many factors responsible for poor symmetry. The impact of a tabbed expander on breast symmetry, however, has not been formally reported. This study aims to evaluate breast symmetry following expander-implant reconstruction using tabbed and non-tabbed tissue expanders. Methods A chart review was performed of 188 consecutive expander-implant reconstructions that met the inclusion criteria of adequate follow-up data and postoperative photographs. Demographic, oncologic, postoperative complication, and photographic data was obtained for each patient. The photographic data was scored using a 4-point scale assessing breast symmetry by three blinded, independent reviewers. Results Of the 188 patients, 74 underwent reconstruction with tabbed expanders and 114 with non-tabbed expanders. The tabbed cohort had significantly higher symmetry scores than the non-tabbed cohort ($2.82/4{\pm}0.86$ vs. $2.55/4{\pm}0.92$, P=0.034). Conclusions The use of tabbed tissue expanders improves breast symmetry in tissue expander-implant-based breast reconstruction. Fixation of the expander to the chest wall allows for more precise control over its location and counteracts the day-to-day translational forces that may influence the shape and location of the expander pocket, mitigating many factors responsible for breast asymmetry.

• Bulletin of the Korean Chemical Society
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• 제5권2호
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• pp.68-73
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• 1984

An enhancement of through-bond interaction by bond angle distortion in pyrazine was examined using various MO methods. Results of MINDO/3 geometry optimization with an angle (${\alpha}$) at $C_2$ atom fixed to 120∼90$^{\circ}$ lead to distorted structures in which the distorted bond is brought closer toward lone pair orbital n of N atom. It was also found that the bond angle distortion increased the P character at the atom $C_2$, resulting in an increased vicinal overlap between n and the $C_2-C_3$ bond. The FMO patterns of ${\sigma}$ framework showed three-fold degeneracy, one of which was of different symmetry which mixes in the symmetry adapted pair, $n_+\;and\;n_-;\;both\;n_+\;and\;n_-$ orbitals thus can interact with both FMOs of the ${\sigma}$ framework. The LCBO-MO analysis with partial elimination of bonds, antibonds or both, however, revealed that the main interaction of $n_+$ was with the HO-${\sigma}$ and that of $n_-$ was with the LU-${\sigma}^{\ast}$ orbital of the ${\sigma}$ framework.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.327.1-327.1
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• 2014

Nitrides-on-silicon structures are considered to be an excellent candidate for unique design architectures and creating devices for high-power applications. Therefore, a lot of effort has been concentrating on growing high-quality III-nitrides on Si substrates, mostly Si(111) and Si(001) substrates. However, there are several fundamental problems in the growth of nitride compound semiconductors on silicon. First, the large difference in lattice constants and thermal expansion coefficients will lead to misfit dislocation and stress in the epitaxial films. Second, the growth of polar compounds on a non-polar substrate can lead to antiphase domains or other defective structures. Even though the lattice mismatches are reached to 16.9 % to GaN and 19 % to AlN and a number of dislocations are originated, Si(111) has been selected as the substrate for the epitaxial growth of nitrides because it is always favored due to its three-fold symmetry at the surface, which gives a good rotational matching for the six-fold symmetry of the wurtzite structure of nitrides. Also, Si(001) has been used for the growth of nitrides due to a possible integration of nitride devices with silicon technology despite a four-fold symmetry and a surface reconstruction. Moreover, Si(110), one of surface orientations used in the silicon technology, begins to attract attention as a substrate for the epitaxial growth of nitrides due to an interesting interface structure. In this system, the close lattice match along the [-1100]AlN/[001]Si direction promotes the faster growth along a particular crystal orientation. However, there are insufficient until now on the studies for the growth of nitride compound semiconductors on Si(110) substrate from a microstructural point of view. In this work, the microstructural properties of nitride thin layers grown on Si(110) have been characterized using various TEM techniques. The main purpose of this study was to understand the atomic structure and the strain behavior of III-nitrides grown on Si(110) substrate by molecular beam epitaxy (MBE). Insight gained at the microscopic level regarding how thin layer grows at the interface is essential for the growth of high quality thin films for various applications.

• Bulletin of the Korean Chemical Society
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• 제17권5호
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• pp.447-452
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• 1996

Three conformational isomers of calix[4]arene butanoate were isolated from the reaction of calix[4]arene and butanoyl chloride in the presence of NaH and their structures were determined by NMR spectra as 1,2-alternate 2a, partial cone 2b and 1,3-alternate conformer 2c, respectively. The crystal structure of 2a has been determined by X-ray diffraction method. The crystals are monoclinic, space group C2/c, a=18.435 (4), b=13.774 (2), c=16.941 (3) Å, β=116.23 (1)°, Z=4, V=3858.8 (12)Å3, Dc=1.21 g cm-3, Dm=1.21 g cm-3. The molecule is in the 1,2-alternate conformation. It has two-fold symmetry axis along the line connecting between C (7AA') and C (7BB') parallel to the b axis of crystal lattice.

• Archives of Plastic Surgery
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• 제40권4호
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• pp.348-352
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• 2013

Background Temporalis muscle transfer produces prompt surgical results with a one-stage operation in facial palsy patients. The orthodromic method is surgically simple, and the vector of muscle action is similar to the temporalis muscle action direction. This article describes transferring temporalis muscle insertion to reconstruct incomplete facial nerve palsy patients. Methods Between August 2009 and November 2011, 6 unilateral incomplete facial nerve palsy patients underwent surgery for orthodromic temporalis muscle transfer. A preauricular incision was performed to expose the mandibular coronoid process. Using a saw, the coronoid process was transected. Three strips of the fascia lata were anchored to the muscle of the nasolabial fold through subcutaneous tunneling. The tension of the strips was adjusted by observing the shape of the nasolabial fold. When optimal tension was achieved, the temporalis muscle was sutured to the strips. The surgical results were assessed by comparing pre- and postoperative photographs. Three independent observers evaluated the photographs. Results The symmetry of the mouth corner was improved in the resting state, and movement of the oral commissure was enhanced in facial animation after surgery. Conclusions The orthodromic transfer of temporalis muscle technique can produce prompt results by applying the natural temporalis muscle vector. This technique preserves residual facial nerve function in incomplete facial nerve palsy patients and produces satisfying cosmetic outcomes without malar muscle bulging, which often occurs in the turn-over technique.

• Journal of Preventive Medicine and Public Health
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• 제49권5호
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• pp.260-274
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• 2016

Objectives: Previous epidemiological studies about oxidative stress and depression are limited by hospital-based case-control design, single-time measurements of oxidative stress biomarkers, and the small number of study participants. Therefore, in this study, we analyzed the association between biomarker of oxidative stress and depressive symptom scores using repeatedly measured panel data from a community-dwelling elderly population. Methods: From 2008 to 2010, a total of 478 elderly participants residing in Seoul, Korea, were evaluated three times. Participants underwent the Korean version of the Short Form Generic Depression Scale (SGDS-K) test for screening depression, and urinary malondialdehyde (MDA) levels were measured as an oxidative stress biomarker. We used a generalized estimating equation with a compound symmetry covariance structure to estimate the effects of oxidative stress on depressive symptom scores. Results: A two-fold increase in urinary MDA concentration was significantly associated with a 33.88% (95% confidence interval [CI], 21.59% to 47.42%) increase in total SGDS-K scores. In subgroup analyses by gender, a two-fold increase in urinary MDA concentration was significantly associated with increased SGDS-K scores in both men and women (men: 30.88%; 95% CI, 10.24% to 55.37%; women: 34.77%; 95% CI, 20.09% to 51.25%). In bivariate analysis after an SGDS-K score ${\geq}8$ was defined as depression, the third and the fourth urinary MDA quartiles showed a significantly increased odds ratio(OR) of depression compared to the lowest urinary MDA quartile (third quartile OR, 6.51; 95% CI, 1.77 to 24.00; fourth quartile OR, 7.11; 95% CI, 1.99 to 25.42). Conclusions: Our study suggests a significant association between oxidative stress and depressive symptoms in the elderly population.

• Wind and Structures
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• 제34권5호
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• pp.407-419
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• 2022

Many factors should be considered by architects and designers for designing a tall building. Wind load is one of these important factors that govern the design of tall building structures and can become a serious challenge when buildings tend to be built very tall and slender. On the other hand, through the initial stages of a design process, choosing the design geometry greatly affects the wind-induced forces on a tall building. With this respect, geometric shapes with 3-fold rotational symmetry are one of the applied plan shapes in tall buildings. This study, therefore, aims to investigate the aerodynamic characteristics of 8 different geometrical shapes using Computational Fluid Dynamics (CFD) by measuring the drag and lift forces. A case study approach was conducted in which different building shape models have the same total gross area and the same height of 300 meters. The simulation was an incompressible transient flow that ran 1700 timesteps (85 seconds on the real-time scale). The results show a great difference between wind-induced force performance of buildings with different plan shapes. Generally, it is stated that the shapes with the same area, but with smaller perimeters, are better choices for reducing the drag force on buildings. Applying the lift force, the results show that the buildings with plan shapes that have rounded corners act better in crosswind flow while, those with sharp corners induce larger forces in the same direction. This study delivers more analytical understanding of building shapes and their behavior against the wind force through the parametric modelling.