• 터널과지하공간
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• 제26권4호
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• pp.327-337
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• 2016

본 연구에서는 화강암 내부의 미세균열 분포에 따른 이방성이 수압파쇄실험 결과에 미치는 영향을 평가하였다. 압력증가율을 일정하게 설정하여 수압파쇄실험을 수행한 결과, 원주방향(주입정 방향과 직교)으로 리프트면이 분포한 시료의 파쇄압력이 가장 낮게 측정되었고, 이는 미세균열의 밀도가 높기 때문이다. 수압파쇄실험과정에서 시료 내부의 변화가 발생하는 주입압력의 크기와 유체 주입속도의 변화 또한 결방향에 따라 분포한 미세균열의 밀도와 관계가 있는 것으로 판단된다. 유체주입속도를 일정하게 설정하여 수압파쇄실험을 수행하였을 경우, 상대적으로 미세균열의 밀도가 높은 리프트면이 원주방향으로 분포된 시료에서 주입압력증가율이 낮게 나타났고, 유체가 침투될 수 있는 균열망이 상대적으로 적게 형성된 그레인면 및 하드웨이면이 원주방향으로 분포된 시료에서는 압력증가율이 높게 나타났다. X-ray CT 촬영을 통해 시료 내부에 생성된 균열의 방향을 확인한 결과, 대부분의 시료에서 리프트면 혹은 그레인면과 평행한 방향으로 균열이 생성된 것을 확인하였고, 이는 암석 내에 상대적으로 미세균열의 밀도가 높아서 분리성이 크기 때문이다.

• Integrative Medicine Research
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• 제7권1호
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• pp.95-102
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• 2018

Background: Hypertension is a major cause of cardiovascular disease and associated mortality, and postmenopausal women are at a high risk of hypertension. We aim to investigate the hypotensive effect and safety of acupuncture, focusing on postmenopausal women with prehypertension and stage 1 hypertension. In addition, we aim to investigate whether the effect of acupuncture treatment differed, depending on Sasang Constitution and cold-heat pattern. Methods: This study is designed as an intervention cohort study. Two hundred postmenopausal women aged <65 years with prehypertension or stage 1 hypertension living in Daejeon city in Korea will be recruited, and randomly assigned to either an acupuncture or no-treatment control group. The intervention will consist of four sessions; one session will include acupuncture performed 10 times for 4 weeks. There will be a 20-week observation period after each session, and the total study duration will be 96 weeks. Acupuncture will be applied at the bilateral Fengchi (GB20), Quchi (LI11), Zusanli (ST36), and Sameumgyo (SP6) acupoints. The effect of acupuncture will be evaluated by comparing the change in systolic and diastolic blood pressure between the acupuncture and control groups every 4 weeks until the end of the study. Discussion: To evaluate the success of blood pressure management, long-term observation is required, but no long-term studies have been conducted to evaluate the effect of acupuncture on blood pressure in postmenopausal women. To our knowledge, this study will be the first long-term study to investigate this issue for more than 6-8 weeks.

• Journal of Advanced Marine Engineering and Technology
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• 제30권4호
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• pp.463-473
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• 2006

The effect of tube diameter on heat and mass transfer characteristics of absorber in absorption chiller/heater using LiBr solution as a working fluid has been investigated by both of numerical and experimental study to develop a high performance and compact absorber. The diameter of the heat exchanger tube inside absorber was changed from 15.88mm to 12.70mm and 9.52mm. In numerical study a model of vapor pressure drop inside tube absorber based on a commercial 20RT absorption chiller/heater was performed. The effect of tube diameter, longitudinal pitch, vapor Reynolds number, longitudinal pitch to diameter ratio on vapor pressure drop across the heat exchanger tube banks inside absorber have been investigated and found that vapor pressure drop decreases as tube diameter increases, longitudinal pitch increases, vapor Reynolds number decreases and longitudinal pitch to diameter ratio increases. In experimental study, a system includes a tube absorber, a generator, solution distribution system and cooling water system was set up. The experimental results shown that the overall heat transfer coefficient, mass transfer coefficient. Nusselt number and Sherwood number increase as solution flow rate increases. In both of study cases, the heat and mass transfer performance increases as tube diameter decreases. Among three different tube diameters the smallest tube diameter 9.52mm has highest heat and mass transfer performance.

• 접착 및 계면
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• 제4권3호
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• pp.9-13
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• 2003

본 연구에서는 점착제의 유지력 개선과 pH 조절을 위해 각각 첨가해 주는 가교제와 pH 조절제의 종류 및 첨가량이 수용성 아크릴 점착제의 점착 물성 및 수용성에 미치는 효과를 알아보기 위하여 중합된 점착 시료에 여러 가지의 가교제와 pH 조절를 첨가해 준 후 초기점착력, 유지력 및 점착력 등의 점착 물성과 수용성을 측정하였다. 가교제를 0.2 wt% 미만 첨가해 주었을 때, 초기 점착력은 감소하였고 유지력과 점착력은 증가하였다. 그러나 0.2 wt% 이상 첨가해 주었을 때는 초기 점착력은 증가하였지만 유지력과 점착력은 감소하는 결과를 보였다. 또한 pH 조절제를 첨가해 주었을 때 pH 조절제의 농도가 증가함에 따라 초기점착력과 수용성은 감소하였고 점착력과 유지력은 증가하였으며, LiOH, KOH, NaOH 순으로 점착 물성과 수용성에 미치는 영향이 큰 것으로 나타났다.

• 산업진흥연구
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• 제9권1호
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• pp.249-257
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• 2024

본 연구는 중국 청년 교사를 대상으로 진로지속학습이 직업적 사명감을 경유하여 진로성공에 미치는 영향에서 진로개발압력의 조건부 직접효과를 확인하는데 연구의 목적이 있다. 자료는 중국 광동지역의 한 대학교에서 유의표집한 청년 교사 354명을 대상으로 설문조사를 통하여 수집하였다. 수집한 자료는 SPSS PC+ Win ver. 25.0과 SPSS PROCESS macro ver. 4.2를 활용하여 분석하였다. 적용된 통계방법은 빈도분석, 신뢰도 분석, 상관분석 및 조건부직접효과 분석이었다. 연구의 결론은 다음과 같다. 첫째, 진로지속학습 및 직업적 사명감은 진로성공과 유의한 양의 상관관계가 있었으나, 진로개발압력과는 유의미한 상관관계가 없는 것으로 나타났다. 진로개발압력은 진로성공과 유의한 음의 상관관계를 보였다. 둘째, 진로지속학습이 직업적 사명감을 경유하여 진로성공에 미치는 영향에서 진로개발압력의 조건부 직접효과가 확인되었다. 이러한 결과를 토대로 본 연구는 대학생들의 진로지속학습 뿐만 아니라 직업적 사명감과 진로개발압력을 동시에 활용하여 진로성공을 증진할 수 있는 방안을 제시하였다.

• Fibers and Polymers
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• 제7권4호
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• pp.404-413
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• 2006

This study examines multiple quality optimization of the injection molding for Polyether Ether Ketone (PEEK). It also looks into the dimensional deviation and strength of screws that are reduced and improved for the molding quality, respectively. This study applies the Taguchi method to cut down on the number of experiments and combines grey relational analysis to determine the optimal processing parameters for multiple quality characteristics. The quality characteristics of this experiment are the screws' outer diameter, tensile strength and twisting strength. First, one should determine the processing parameters that may affect the injection molding with the $L_{18}(2^1{\times}3^7)$ orthogonal, including mold temperature, pre-plasticity amount, injection pressure, injection speed, screw speed, packing pressure, packing time and cooling time. Then, the grey relational analysis, whose response table and response graph indicate the optimum processing parameters for multiple quality characteristics, is applied to resolve this drawback. The Taguchi method only takes a single quality characteristic into consideration. Finally, a processing parameter prediction system is established by using the back-propagation neural network. The percentage errors all fall within 2%, between the predicted values and the target values. This reveals that the prediction system established in this study produces excellent results.

• 한국분말재료학회지
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• 제25권1호
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• pp.48-53
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• 2018

One-dimensional rutile $TiO_2$ is an important inorganic compound with applicability in sensors, solar cells, and Li-based batteries. However, conventional synthesis methods for $TiO_2$ nanowires are complicated and entail risks of environmental contamination. In this work, we report the growth of $TiO_2$ nanowires on a Ti alloy powder (Ti-6wt%Al-4wt%V, Ti64) using simple thermal oxidation under a limited supply of $O_2$. The optimum condition for $TiO_2$ nanowire synthesis is studied for variables including temperature, time, and pressure. $TiO_2$ nanowires of ${\sim}5{\mu}m$ in length and 100 nm in thickness are richly synthesized under the optimum condition with single-crystalline rutile phases. The formation of $TiO_2$ nanowires is greatly influenced by synthesis temperature and pressure. The synthesized $TiO_2$ nanowires are characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM).

• The Korean Journal of Physiology and Pharmacology
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• 제26권6호
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• pp.469-478
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• 2022

WNT signaling plays an important role in cardiac development, but abnormal activity is often associated with cardiac hypertrophy, myocardial infarction, remodeling, and heart failure. The effect of WNT signaling on regulation of atrial natriuretic peptide (ANP) secretion is unclear. Therefore, the purpose of this study was to investigate the effect of Wnt agonist 1 (Wnta1) on ANP secretion and mechanical dynamics in beating rat atria. Wnta1 treatment significantly increased atrial ANP secretion and pulse pressure; these effects were blocked by U73122, an antagonist of phospholipase C. U73122 also abolished the effects of Wnta1-mediated upregulation of protein kinase C (PKC) β and γ expression, and the PKC antagonist Go 6983 eliminated Wnta1-induced secretion of ANP. In addition, Wnta1 upregulated levels of phospho-transforming growth factor-β activated kinase 1 (p-TAK1), TAK1 banding 1 (TAB1) and phospho-activating transcription factor 2 (p-ATF2); these effects were blocked by both U73122 and Go 6983. Wnta1-induced ATF2 was abrogated by inhibition of TAK1. Furthermore, Wnta1 upregulated the expression of T cell factor (TCF) 3, TCF4, and lymphoid enhancer factor 1 (LEF1), and these effects were blocked by U73122 and Go 6983. Tak1 inhibition abolished the Wnta1-induced expression of TCF3, TCF4, and LEF1 and Wnta1-mediated ANP secretion and changes in mechanical dynamics. These results suggest that Wnta1 increased the secretion of ANP and mechanical dynamics in beating rat atria by activation of PKC-TAK1-ATF2-TCF3/LEF1 and TCF4/LEF1 signaling mainly via the WNT/Ca²⁺ pathway. It is also suggested that WNT-ANP signaling is implicated in cardiac physiology and pathophysiology.

• Korean Journal of Acupuncture
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• 제25권2호
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• pp.125-141
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• 2008

Objective : The aim of this study is to investigate the curative effect of Bee Venom Acupuncture Therapy for pain and limited R.O.M (range of motion) of shoulder in stroke patients. Methods : The subjects of this study were 6 patients with shoulder pain in stroke sequelae. Routine Oriental Medical programs (Acupunture, moxibustion, herbal medicine and physical therapy) were maintained for each subject throughout this study. Single subject ABABAB design was adopted. Each period was 4 days as a rule. Only during the treatment period, Bee Venom Acupuncture Therapy was provided as intervention at the acupoints of LI15(Gyeonu),　TE14(Gyeollyo), GB21(Gyeonjeong), LI14(Bino). The change of pain was measured with a Visual Analogue Scale(VAS). The pain threshold was measured using pressure algometer at the same acupoints where Bee Venom Acupuncture Therapy was provided. And the R.O.M of shoulder joint (flexion, extension, abduction, adduction, external rotation, internal rotation) was measured as well. Analysis was performed by Bayesian analysis using WinBUGS for the comparison of treatment(Bee Venom Acupuncture Therapy) and non-treatment. Results : The median overall improvement for difference in VAS was -2.219(-3.213, -1.175), for difference in external rotation of shoulder R.O.M was 9.992(-2.298, 18.49), for difference in tenderness score of LI14(Bino) by pressure algometer was 5.05(0.6283, 7.762). 95% credibility intervals being shown in brackets. However, the median overall improvement for difference in the other measurements was not significant. Conclusion : This study suggests that Bee Venom Therapy may be applicable to decrease pain and improve R.O.M of shoulder in hemiplegia patients with stroke. Further elaborated single subject designs need to be accumulated to confirm the effects of Bee Venom Acupunture Therapy on shoulder pain in patients with stroke sequelae.

• 한국식품저장유통학회지
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• 제18권1호
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• pp.1-6
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• 2011

고추장굴비의 지방산패를 최소화하기 위하여 신선굴비를 동결건조한 굴비포를 사용하여 고추장굴비를 제조하고 비열처리 살균방법으로 초고압과 감마선 처리하여 저장 중에 품질과 미생물변화를 분석함으로서 고추장굴비의 저장과 유통기간 연장 가능성을 검토하였다. 초고압처리(200, 400, 600 MPa) 및 감마선 조사(7, 10, 20, 30 kGy) 후 pH 변화는 유의적으로 차이가 없었으며 20일 동안 상온에서 저장 중에도 시료간의 유의적인 변화를 보이지 않았다. 색도는 Hunter L값과 b값은 증가하는 경향을 보였으며 a값은 감소하는 경향을 보였으나 외관상 품질에 영향을 미칠 정도는 아니었다. 휘발성 염기질소 대조구와 처리구에서 저장 중 경시적으로 증가하는 현상을 보였으나 초고압처리 압력이 높을수록, 감마선 조사강도가 높을수록 유의적으로 현저히 낮은 증가율을 보였다. TBA값은 모든 시료에서 시간이 경과함에 따라 증가량의 차이는 있으나 증가하는 경향을 보였으며, 초고압 처리하지 않은 경우 초기 0.6 mg/g 수준에서 20일 저장 후 4.2 mg/g 수준으로 높은 증가율을 보였으며, 600 MPa 처리구와 30 KGy 처리구의 경우 각각 1.2mg/g과 1.5 mg/g 수준으로 현저하게 낮은 값을 보였다. 초고압처리에 의한 호기성 생균수 감소효과는 다소 낮은 편이었으며 10 kGy 이상의 방사선 조사에 의해 효과적으로 미생물 수를 감소시켰다. 특히 30 kGy 처리구의 경우 20일 동안 저장 후에도 검출되지 않아 멸균효과를 얻을 수 있었다. 고추장 굴비 대중화를 위해서 진공포장이 기본적으로 요구되며, 초고압처리 방법은 단기적인 유통기한 연장효과를 기대할 수 있으며 장기적인 효과를 위해서는 감마선 조사가 적합할 것으로 판단된다.