• 한국분말재료학회지
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• 제6권4호
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• pp.314-319
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• 1999

The solid state reaction by mechanical alloying(MA) generally proceeds by lowering the free energy as the result of a chemical reaction at the interface between the two adjacent layers. However, Lee et $al.^{1-5)}$ reported that a mixture of Cu and Ta, the combination of which is characterized by a positive heat of mixing of +2kJ/mol, could be amorphized by mechanical alloying. This implies that there exists an up-hill process to raise the free energy of a mixture of pure Cu and la to that of an amorphous phase. It is our aim to investigate to what extent the MA is capable of producing a non-equilibrium phase with increasing the heat of mixing. The system chosen was the ternary $Cu_{30}Ta_{ 70-x}Mo_ x$ (x=35, 10). The mechanical alloying was carried out using a Fritsch P-5 planetary mill under Ar gas atmosphere. The MA powders were characterized by the X-ray diffraction with Cu-K $\alpha$ radiation, thermal analysis, electron diffraction and TEM micrographs. In the case of x=35, where pure Cu powders were mixed with equal amount of pure Ta and Mo powders, we revealed the formation of bcc solid solution after 150 h milling but its gradual decomposition by releasing fcc-Cu when milling time exceeded 200 h. However, an amorphous phase was clearly formed when the Mo content was lowered to x=10. It is believed that the amorphization of ternary $Cu_{30}Ta_{60}Mo_{10}$ powders is essentially identical to the solid state amorphization process in binary $Cu_{30}Ta_{70}$ powders.

• Journal of Acupuncture Research
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• 제37권2호
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• pp.94-101
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• 2020

Background: Several Korean medical doctors have been practicing applied kinesiology (AK), invented in 1964 by Dr. George J Goodheart, USA. Although the efficacy of traditional acupuncture (TA) and pharmacopucture treatment for lumbar conditions/diseases has been examined, the possible benefits of combining TA and AK have not been reported. Therefore, the aim of this study was to report the effects of combining TA and AK treatment for lumbar disorders using the Japanese Orthopedic Association lumbar score (JOALS) assessment. Methods: There were 21 outpatients treated at Samse Korean Traditional Hospital between March 2018 and September 2018, who presented with L4/L5 or L5/S1 root radiculopathy associated with lumbar spinal stenosis (LSS) and lumbar herniation of intervertebral disk (LHID). They were treated 10×(2 sessions per week, for 5 weeks) with TA and AK approaches that included a category block, manipulation or strain/counterstrain treatments. The primary outcome was mainly assessed using the JOALS score which was used before (0 ×), during (5 ×), and after treatment (10 ×). Results: There were 19 patients diagnosed with LSS and 2 were diagnosed with LHID. Using the JOALS assessment, TA and AK combined approaches improved the lumbar conditions of all 21 patients after 5 × treatmentsand continued to improve after 10 × treatments (p < 0.001). Conclusion: Combined TA and AK treatment was effective in treating spinal conditions/diseases. Prospective, relevant, well-controlled protocols for TA and AK therapies for various conditions are needed.

• The Journal of Korean Physical Therapy
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• 제33권6호
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• pp.278-285
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• 2021

Purpose: This study investigated the effects of open kinetic chain (OKC) exercise for the gastrocnemius (GCM) and tibialis anterior (TA) muscles on static and dynamic balance and muscle strength. Methods: We recruited 21 healthy participants, dividing them into 3 groups (GCM, TA, and non-exercise). Each group contains 7 participants. Two exercise groups (GCM and TA) performed OKC exercise with elastic bands twice per week for 4 weeks, while non-exercise group did nothing. We obtained the data for static and dynamic balance and muscle strength before and after the intervention. We used the Kruskal-Wallis test to compare and analyze the pre-post-intervention differences among the groups. Results: For static balance, the stability index of the TA group was the lowest for the dynamic platform (p<0.05). The dynamic balance of the TA group increased for the anterior and posteromedial directions (p<0.05). The peak torque increased in the TA group for dorsiflexion (D/F) movement and in the GCM group for plantar flexion movement compared with the other groups, except for the left direction during D/F (p<0.05). Conclusion: OKC exercises with elastic bands were effective for selectively increasing muscle strength. It is clinically thought that strength training for TA muscles will be effective among the muscles of the ankle.

• 한국재료학회지
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• 제11권12호
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• pp.1047-1051
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• 2001

Purity tantalum powder has been produced by sodium reduction of potassium tantalum fluoride($K_2TaF_7$)in a stainless steel bomb. The influence of experimental variable, such as excess of reductant and temperature of reduction on the yield and quality of the Ta powder has been studied. The excesses of reductant were varied from -20%, -10%, 0%, 5%, 10%, 20%. When -20% excess of sodium was used, the un-reacted sodium remained in the reacted product. The yield of 81% of Ta powder has been achieved by reducing 50g of$K_TaF_7$with 5% sodium in excess of stoichiometric amount in presence of 16.8g of sodium chloride in the charge at a reduction temperature of$905{\circ}C$. The proportion of fine fraction(~325mesh) decreased appreciably with the increase of sodium excess, and the yield of tantalum powder improved from 65% to 94%. The average particle size of Ta Powder is improved from 3 microns to 4 microns in the 5% excess sodium.

• Biomolecules & Therapeutics
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• 제18권2호
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• pp.211-218
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• 2010

Acanthopanax koreanum Nakai (Araliaceae) is a medicinal plant indigenous to Korea. The root and stem barks of Acanthopanax species have been used as a tonic and sedative as well as in the treatment of rheumatism and diabetes. In our study, three lignans, eleutheroside E (EE), tortoside A (TA), and syringaresinol (SY), were isolated from the stem and root of A. koreanum in an effort to study the immunomodulating effect. We treated natural killer cells and dendritic cells with lignans (EE, TA, or SY), and analyzed their cytokine (IL-12 and IFN-${\gamma}$) secretion. EE, TA, or SY markedly enhanced IL-12 secretion in mouse lymphoid (DC1) and myeloid type (DC2.4) dendritic cells after 48 hr of treatment. There were no significant differences in the cytokine stimulatory effects between EE, TA, or SY. Moreover, treatment of EE, TA, or SY significantly induced IFN-${\gamma}$ secretion by human NK cells (NK92MI) confirmed by ELISA assay. This study suggests that lignans from A. koreanum modulate cytokines, and that such modulation may provide the mechanism of action for many of their therapeutic effects.

• 한국결정성장학회지
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• 제7권4호
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• pp.528-535
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• 1997

Halogen type floating zone system을 이용하여 직경 6 mm, 길이가 20 mm인 조화용융조성(congruently melting composition)의 $LiTaO_3$(LT) 단결정을 성장시켰다. 최적의 분말합성조건, 원료봉의 소결조건, 결정 성장조건을 확립하였다. 공기나 질소분위기에서는 결정성장이 불가능하였으나 아르곤 분위기에서는 안정한 형태의 용융대를 형성 및 유지할 수 있어서 결정성장이 용이하게 진행될 수 있었다. 성장된 결정으로 Laue back reflection pattern, 전이온도, 굴절율분포, 투과율을 측정하여 성장된 결정의 물성을 평가하였다. 성장된 결정의 부분별(top, body, tail) 전이온도 차가 $1^{\circ}C$로 측정되어 floating zone(FZ)법으로 성장된 LT결정이 조성적으로 균일함을 확인할 수 있었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.79-80
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• 2013

The purpose of this study was to investigate $2^{nd} $nanotube formed surface observation of the Ti-25Ta-xZr alloys using ATO(anodic titanium oxide) technique. Ti-25Ta-xZr alloy was anodized in 1M $H_3PO_4$ electrolytes containing 0.8 Wt. % NaF at room temperature. After formation of nanotube was achieved out, nanotube was eliminated, and then anodization was carried out repeatedly. The microstructures, phase transformation, and morphology of nanotubular Ti-25Ta-xZr alloys and process of nanotube growth by using ATO method was examined by optical microscopy (OM), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The ${\alpha}$ phase and ${\beta}$ phases were affected to form the second nanotube morphology of Ti-25Ta-xZr alloys.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.171-171
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• 2003

공정기술의 향상으로 DRAM(dynamic random acess memory)의 고집적화가 이루어지고 있으며, 각 개별소자 및 셀 영역의 점유면적의 감소가 요구되어지고 있다. 따라서 기존에 사용하던 NO (Si$_3$N$_4$/SiO$_2$)박막보다 유전율이 높은 고유전물질에 대한 연구가 진행되고 있다. Ta$_2$O$_{5}$, $Y_2$O$_3$, HfO$_2$, ZrO$_2$,Nb$_2$O$_{5}$, BaTiO$_3$, SrTiO$_3$ 및 (BaSr)TiO등이 고유전물질로 연구되고 있는데 그 중 공정의 안정성, 누설전류의 우수성으로 인해 Ta$_2$O$_{5}$이 많이 연구되고 있다. 본 실험에서는 TiO$_2$가 8 mol%가 첨가된 Ta$_2$O$_{5}$의 열처리 온도에 따른 전기적, 유전특성을 살펴보려고 한다살펴보려고 한다

• 한국대기환경학회지
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• 제1권1호
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• pp.71-82
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• 1985

The effect on the particulate matters in the atmosphere was investigated in Seoul area from March, 1984 to Aprill, 1985. Aerosols were collected by filters on nine stages Andrsen Air Sampler, and size distribution and total concentration of the aerosols, Fe and Pb were measured. In spring with Yellow Sand the concentration of particles in aerosols was 185.55$\mug/m^3$ and CP/TA was 65.9%. But in spring without Yellow Sand those of particles was 135.45$\mug/m^3$ and CP/TA was 58.6%. Accordingly the concentration of coarse particles with Yellow Sand was higher than without them in Spring. Above results indicate that in Seoul Area the main source of air pollution originated from natural burdens, especially from soil. The concentration of Pb was similarly valued through both seasons in Seoul area but fine particles valued above coarse particles. On the other hand, in urban area, the natural and anthropogenic sources have influenced on the concentration of Pb. With referred to particle size distribution for Fe, the concentration of coarse particles was 0.168$\etag/m^3$ (CP/TA: 74.3%) in Spring with Yellow Sand, 0.096$\mug/m^3$ (CP/TA: 71.6%) without Yellow Sand and 0.083$\mug/m^3$ (CP/TA: 67.4%) in winter, respectively. Compared with fine particles, all of them were higher. It indicated that the origin of coarse particles in urban air was not related to anthropogenic source. The concentration of Fe was influenced by Yellow Sand and contributed to air pollution.

• 한국재료학회지
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• 제14권10호
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• pp.719-724
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• 2004

Production of fine tantalum powder by calciothermic reduction of tantalum oxides ($Ta_{2}O_5$) pellet through an electronically mediated reaction (EMR) has been investigated. $Ta_{2}O_5$ pellet feed and reductant calcium-nickel (Ca-Ni) alloy were charged into electronically isolated locations in a molten $CaCl_2$ bath. The current flow through an external path between the feed (cathode) and reductant (anode) locations was monitored. The current approximately 4.7A was measured during the reaction in the external circuit connecting cathode and anode location. Tantalum powder with approximately 99 $mass\%$ purity was readily obtained after each experiment. Tantalum powder by EMR using $Ta_{2}O_5$ pellet feed was fine compared with that of metal powder by metallothermic reduction and EMR using $Ta_{2}O_5$ powder feed.