• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.297-302
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• 2022

We investigated the origin of magnetic behaviors induced by an asymmetric spin exchange interaction in Fe-site engineered lead iron niobate [Pb(Fe_1/2Nb_1/2)O₃, PFN], which exhibits a room-temperature multiferroicity. The magnitude of spin exchange interaction was regulated by the introduced transition metals with a distinct Bohr magneton, i.e., Cr, Co, and Ni. All compositions were found to have a single-phase perovskite structure keeping their ferroelectric order except for Cr introduction. We discovered that the incorporation of each transition metal imposes a distinct magnetic behavior on the lead iron niobate system; antiferro-, hard ferro-, and soft ferromagnetism for Cr, Co, and Ni, respectively. This indicates that orbital occupancy and interatomic distance play key roles in the determination of magnetic behavior rather than the magnitude of the individual Bohr magneton. Further investigations are planned, such as X-ray absorption spectroscopy, to clarify the origin of magnetic properties in this system.

• 대한화학회지
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• 제56권6호
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• pp.679-691
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• 2012

New series of metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Pt(II) with 4-(p-chlorophenyl)-1-(pyridin-2-yl)thiosemicarbazide (HCPTS) have been synthesized and characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, $^1H$ NMR, mass and ESR) and thermal studies. The IR data suggest different coordination modes for HCPTS which behaves as a monobasic bidentate with all metal ions except Cu(II) and Zn(II) which acts as a monobasic tridentate. Based on the electronic and magnetic studies, Co(II), Cu(II), Pd(II) and Pt(II) complexes have square - planner, Ni(II) has mixed stereochemistry (tetrahedral + square planar), while Zn(II) is tetrahedral. Molar conductance in DMF solution indicates the non-ionic nature of the complexes. The ESR spectra of solid copper(II) complex show $g_{\parallel}$ (2.2221) > $g_{\perp}$ (2.0899) > 2.0023 indicating square-planar structure and the presence of the unpaired electron in the $d_x2_{-y}2$ orbital with significant covalent bond character. The thermal stability and degradation kinetics of the ligand and its metal complexes were studied by TGA and DTA and the kinetic parameters were calculated using Coats-Redfern and Horowitz-Metzger methods. The complexes have more antibacterial activity against some bacteria than the free ligand. However, the ligand has high anticancer activities against HCT116 (human colon carcinoma cell line) and HEPG2 (human liver hepatocellular carcinoma cell line) compared with its complexes.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1996년도 추계학술발표회 논문집
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• pp.18-28
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• 1996

The outer-most electrons of metal atoms and the remaining valence electrons of any molecular atoms make three-dimensional crystallizing $\pi$-bondings. The rotating electrons on the three-dimensional crystallizing $\pi$-bonding orbitals of atoms make $\pi$-far infrared rays. Longitudinal wave is a propagation of a bundle of $\pi$-far infrared rays, which are produced by a dynamic impact on a solid bar. The $\pi$-far infrared rays make three-dimensional crystallizing $\pi$-bondings in the material, which reproduce the same $\pi$-far infrared rays. If a current signal is input into water molecules under a given electric potential field with $\pi$-far infrared rays (input information), the signal can be amplified because the $\pi$-far infrared rays make the $\pi$-bondings, which reduce electric resistance. The three-dimensional crystallizing $\pi$-bondings can induce normal electrons to move from one orbital to next one with a aid of potential electric field. Quantum Resonance Spectrometer is composed of tesla coil absorbing $\pi$-far infrared rays, tesla coil emitting varying electromagnetic waves signal generator, signal storage, human body amplifier, signal analyzer and data indicator. The absorbing tesla coil making varying magnetic field and downward and upward electric field, which resonates the $\pi$-far infrared rays coming out from specimen and absorbs them. The modulated current signal from the input square signal can generate and emit varying electromagnetic waves from the tesla coil. The varying electro-magnetic waves make the three-dimensional crystallizing $\pi$-bondings and the $\pi$-far infrared rays in the water molecules.

• 한국자기공명학회논문지
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• 제16권1호
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• pp.78-90
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• 2012

To understand the electronic structure of $[NiS_4]^-$ complex ions, two complexes with such $[NiS_4]^-$ core, $FcCH=CHPymCH_3[Ni(dmit)_2]$ (Pym = pyridinium, $dmit^{2-}$ = 2-thioxo-1,3-dithiole-4,5-dithiolate) and $FcCH=CHPymCH_3[Ni(dddt)_2]{\cdot}{\frac{1}{2}}H_2O$ ($dddt^{2-}=5,6-dihydro-1,4-dithiin-2,3-dithiolato$), were synthesized to be characterized by X-ray crystallography, single crystal electron paramagnetic resonance (EPR) and density functional theory (DFT) calculation. Powder EPR spectra show narrow g-anisotropy but the anisotropy is bigger in $[Ni(dmit)_2]^-$ than in $[Ni(dddt)_2]^-$, indicating bigger spin density in Ni(III) d-orbital of $[Ni(dmit)_2]^-$ than in $[Ni(dddt)_2]^-$, which is consistent to DFT results. EPR studies of the crystals of the complexes surprisingly suggest that the $g_y$-axis of $[Ni(dddt)_2]^-$ is approximately on or perpendicular to the $[NiS_4]^-$ plane while the $g_y$-axis of $[Ni(dmit)_2]^-$ is on the plane, though DFT study of the complexes of this study and previously reported $[NiS_4]^-$ complexes indicate that the $g_y$-axis is on the $[NiS_4]^-$ plane.

• 한국기계가공학회지
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• 제11권3호
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• pp.138-145
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• 2012

The material used in this study is dielectric and ferrite. Because of the unique characteristics of the material, it is easily exposed to external shocks and pressure, which cause damage to the product. However, after being processed under high-temperature environment repeatedly, the mechanical strength of the product is greatly increased due to the change of the electrical properties. In this paper, dielectric and bonded ferrite material was tested for the material properties. The equipment for this experiment was produced and tested to allow Cylindrical and Three-dimensional geometry of the product for the vacuum deposition. For Cylindrical shape of the product, in order to obtain the equivalent film thickness, the device is constructed in a vacuum chamber which gives arbitrary revolving and rotating capability. The electrical performance of the product is obtained through this process as well. However, as mentioned above, with repeating processes under high temperature and exposure to external environment, the product is easy to be broken. This experiment has enabled us to find out a stable condition to apply the communication of the RF high frequency to each of the core elements, such as Ferrite and Dielectric which is then used for the mechanical strength of the Raw material, hetero-junction material, Hetero-junction Ag Coating material and hetero-junction Ag Coating SiO2 Coating material respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.63.2-63.2
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• 2015

Controlling and sensing spin states of magnetic molecules such as metallo-porphyrins at the single molecule level is essential for spintronic molecular device applications. Axial coordinations of diatomic molecules to metallo-porphyrins also play key roles in dynamic processes of biological functions such as blood pressure control and immune response. However, probing such reactions at the single molecule level to understand their physical mechanisms has been rarely performed. Here we present on our single molecule association and dissociation experiments between diatomic and metallo-porphyrin molecules on Au(111) describing its adsorption structures, spin states, and dissociation mechanisms. We observed bright ring shapes in NO adsorbed metallo-porphyrin compelxes and explained them by considering tilted binding and precession motion of NO. Before NO exposure, Co-porphryin showed a clear zero-bias peak in scanning tunneling spectroscopy, a signature of Kondo effect in STS, whereas after NO exposures it formed a molecular complex, NO-Co-porphyrin, that did not show any zero-bias feature implying that the Kondo effect was switched off by binding of NO. Under tunneling junctions of scanning tunneling microscope, both positive and negative energy pulses. From the observed power law relations between dissociation rate and tunneling current, we argue that the dissociations were inelastically induced with molecular orbital resonances. Our study shows that single molecule association and dissociation can be used to probe spin states and reaction mechanisms in a variety of axial coordination between small molecules and metallo-porphyrins.

• Journal of Korean Neurosurgical Society
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• 제52권4호
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• pp.420-422
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• 2012

Cerebral aspergillosis is rare and usually misdiagnosed because its presentation is similar to that of a tumor. The correct diagnosis is usually made intra-operatively. Cerebral abscess with fungal infection is extremely rare and few cases have been reported, but it carries a poor prognosis. A 73 year-old man presented with decreased visual acuity and paresis of the right cranial nerve III. Magnetic resonance imaging (MRI) revealed a mass in the right cavernous sinus, extened to the anterior crainial fossa and the superior orbital fissure. During surgery, a well encapsulated pus pocket was found, and histopathological examination of the mass resulted in the diagnosis of aspergillosis. Despite appropriate anti-fungal treatment, the patient eventually died from fatal cerebral ischemic change and severe brain swelling. The correct diagnosis of cerebral aspergillosis can only be achieved by histopathological examination because clinical and radiological findings including MRI are not specific. Surgical intervention and antifungal therapy should be considered the optimal treatment. Early diagnosis and aggressive antifungal treatment provide good results.

• Archives of Plastic Surgery
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• 제38권6호
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• pp.875-878
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• 2011

Purpose: Absorbable implants are frequently used to fix facial bone fractures, because they are radiolucent and compatible with magnetic resonance imaging (MRI). Despite their increasing usage, however, there have been few reports about their long-term side-effects. In this paper, a case in which absorbable implants led to a foreign body reaction 17 months after their insertion is presented. Methods: A previously healthy 19-year-old male fell from a flight of stairs and visited the authors' hospital with right periorbital pain. Zygomaticomaxillary fracture involving right orbital floor was detected via a facial bone computed tomography (CT). Internal fixation with absorbable implants was followed by open reduction. 17 months after the surgery, the patient complained of localized periorbital swelling. Removal of the granulomatous lesion including the absorbable implants along with their biopsy and culture was performed. Results: The granulomatous lesion around the implants was firm and extended into the maxillary sinus. The histologic finding showed a microabscess with a foreign body reaction. Methicillin-sensitive Staphylococcus aureus growth was confirmed in the culture. No definite abnormal symptoms ensued after the complete removal. Conclusion: A microabscess-forming granulomatous lesion around the absorbable implant can cause delayed symptomatic foreign body reaction despite its rare occurrence. Complete removal of the lesion including implants is expected to have a successful outcome if it is encountered.

• 한국자기학회지
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• 제4권2호
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• pp.100-105
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• 1994

대표적인 연자성재료 중의 하나로 알려진 Ni-Fe 합금박막을 고주파 마그네트론 스파터링 장치를 사용하여 제작했다. 박막두께가 Ni-Fe 합금박막의 특성에 미치는 영향을 고찰하기 위하여, 스파터링 시간을 변화시켜 주면서 제작된 시료에 대해 강자성 공명 실험에서 얻은 미분형 공명흡 수곡선을 분석하여, 유효자화 $M_{eff}$, 교환상수(exchange stiffness constant) A, 그리고 분 광학적 분리인자 g를 구했다. 모든 시료에 대해 유효자화는 거의 일정한 값을 보였으나, 교환상수 는 시료의 두께가 증가함에 따라 비교적 큰 증가폭을 나타냈다. 분광학적 분리인자는 시료의 두께 가 증가함에 따라 약간 증가하는 경향성을 보였는데, 이는 스핀자기모멘트에 대한 궤도자기모멘트 의 상대적인 기여가 증가했기 때문인 것으로 생각된다.

• 천문학회지
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• 제44권3호
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• pp.89-96
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• 2011

We present results of two-color VR photometry of the intermediate polar RXS J1803. The data were aquired using the Korean 1-m telescope located at Mt. Lemmon, USA. Different "high" and "low" luminosity states, similar to other intermediate polars, were discovered. No statistically significant variability of the color index with varying luminosity was detected. The orbital variability was found to be not statistically significant. Spin maxima timings were determined, as well as the photometric ephemeris for the time interval of our observations. The spin period variations, caused by interaction of the accretion structure with the rotating magnetic white dwarf, were also detected. These variations are of complicated character, and their study requires further observations. We determine the color transformation coefficients for our photometric systems, and improve on the secondary photometric standards.