• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.28-37
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• 2022

The lignite and bituminous coal are mainly used in thermal power plant. They exhaust green house gas (GHG) such as CO₂, and become deplete, thus require alternative energy resources. To solve the problem, the hydrochar production from biomass is suggested. In this study, both hydrothermal carbonization (HTC) and solvothermal carbonization (STC) were used to produce high quality hydrochar. To improve the reactivity of water solvent process in HTC, STC process was conducted using ethanol solution. The experiments were carried out by varying the solid-liquid ratio (1:4, 1:8, 1:12), reaction temperature (150~300 ℃) and retention time (15~120 min) using kenaf. The characteristic of hydrochar was analyzed by EA, FT-IR, TGA and SEM. The carbon content of hydrochar increased up to 48.11%, while the volatile matter decreased up to 39.34%. Additionally, the fuel characteristic of hydrochar was enhanced by reaction temperature. The results showed that the kenaf converted to a fuel by HTC and STC process, which can be used as an alternative energy source of coal.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.165-165
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• 2017

지난 수 십 년 동안, 전 세계적으로 자원의 소비가 급격히 증가하게 되면서 최근 자원 고갈은 물론 환경오염이 커다란 이슈로 문제가 되고 있다. 이에 따라 재료 관련 분야에 있어서는 보다 효율적이고 친환경적인 방법으로 자원을 활용해야 된다는 필요성이 대두되었고 이와 같은 관점에서 목적하는 성분이 우수하고 환경 친화적인 표면처리 재료 개발연구가 활발하게 진행되고 있는 실정이다. 그 중 플라즈마 전해 산화(Plasma Electrolytic Oxidation, PEO)는 알루미늄, 마그네슘 등의 경금속의 경도를 향상시키고 높은 내마모성, 내식성을 갖게 하는 표면처리로써 그 관심이 증가하고 있다. 이 플라즈마 전해 산화는 일반적으로 공정비용 대비 효과적이고 환경 친화적이며 코팅 성능 면에서 우수하다고 알려져 있다. 이러한 고유한 특성으로 인해 플라즈마 전해 산화 코팅은 최근 몇 년 동안 기계, 자동차, 우주항공, 의학 및 전기 산업 등의 분야에서 그 적용이 점차 증가하고 있는 상황이다. 한편, 플라즈마 전해 산화 코팅을 하는 모재들의 경우 부동태 산화피막을 용이하게 형성할 수 있는 특성의 모재에 한정되고 있어서 그 응용확대에 한계가 있는 것이 사실이다. 따라서 본 연구에서는 플라즈마 전해 산화법을 사용하여 용융알루미늄도금 강판 상에 산화피막 형성을 시도하였다. 전원공급 장치의 양극은 전해질 속에 잠겨있는 작동전극에 연결하고 음극은 대전극 역할을 하는 스테인레스강 전해질 용기에 연결되었다. 전해질은 Sodium Aluminate 및 기타 첨가제를 함유한 것을 사용하였고 온도는 열교환기를 사용하여 $30^{\circ}C$ 이하로 유지되었다. 또한 여기서 전류밀도는 $5{\sim}10A/dm^2$, 실험 주파수는 700Hz, Duty cycle은 30 및 90%의 각 조건에서 공정처리 시간을 각각 30분 및 60분 동안 진행하였다. 이와 같은 조건에서 형성한 막들에 대해서는 주사형전자현미경(SEM)을 이용하여 코팅 막의 표면 및 단면의 모폴로지를 관찰하였음은 물론 EDS 및 XRD 측정을 통하여 원소조성분포 및 결정구조를 각각 분석하였다. 또한 이 코팅 막들에 대한 내식성은 5% 염수분무 환경 중 노출시험(Salt spray test), 3% NaCl 용액에서의 침지 시험 및 전기화학적 동전위 양극분극(Potentiodynamic Polarization) 시험을 진행하여 평가하였다. 이상의 실험결과에 의하면, 제작조건별 플라즈마 전해 산화 코팅 막의 모폴로지 및 결정구조가 상이하게 나타나는 것을 알 수 있었다. 코팅 막의 모폴로지 관찰 결과, 공정 시간에 비례하여 표면에 존재하는 원형 기공의 수는 감소하였으나 그 크기가 커지고 크레이터의 직경 또한 커진 것이 확인되었다. 이 기공은 마이크로 방전에 의해 형성된다고 알려져 있는데 공정 시간이 증가함에 따라 코팅 두께가 점차 증가하여 마이크로 방전의 빈도수가 줄어들고 그 강도는 증가하게 되어 기공 크기가 증가한 것으로 사료된다. 또한 공정시간이 긴 시편에서 표면에 크랙이 다수 존재하는 것으로 확인되었다. 이것은 방전에 의해 고온이 된 소재가 차가운 전해질과 만나게 되어 생긴 큰 온도구배로 인해 강한 열응력이 발생하여 균열을 초래한 것으로 보인다. 조성원소 분석 결과 원형 기공 주변의 크레이터 영역에는 알루미늄이 풍부하였으며 그 주변에 결절상을 갖는 구조에서는 전해질 성분의 원소가 포함되어 있는 것이 확인되었다. 이러한 코팅 막의 표면 특성은 내식성에 영향을 주게 된 원인으로 사료된다. 동전위 분극측정 결과에 의하면 플라즈마 전해 산화 공정 시간이 길어질수록 부식전류밀도가 증가하였다. 이것은 공정시간이 길어짐에 따라 강한 방전이 발생하여 기공의 크기가 증가하고 크랙이 발생하게 되면서 내식성이 저하된 것으로 판단된다. 종합적으로 재료특성 분석 및 내식성 평가를 분석한 결과, 플라즈마 전해 산화의 공정 시간이 너무 길게 되면 오히려 내식성은 저하되는 것이 확인되었다. 이상의 연구를 통하여 고내식 특성을 갖는 플라즈마 전해 산화 막의 유효성을 확인하였으며 용융알루미늄강판 상에 실시한 플라즈마 전해 산화 처리에 대한 기초적인 응용 지침을 제시할 수 있을 것으로 사료된다.

• Journal of Life Science
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• v.34 no.10
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• pp.701-712
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• 2024

Fucoidan is a polysaccharide found in brown algae, which is known for its various bioactive effects, including immune enhancement, anti-cancer, and anti-inflammatory properties. In this study, the effects of fucoidan on cellular and mitochondrial damage, as well as changes in osteogenic and osteoclastic activities induced by advanced glycation end-products (AGEs) in MC3T3-E1 osteoblast-like cells, were investigated. Treatment with AGEs resulted in a time- and dose-dependent decrease in MTT reduction capacity, activation of caspases (-3, -8, and -9), and an increase in apoptosis. Pre-treatment with fucoidan significantly alleviated these cellular damage markers caused by AGEs. In addition, fucoidan protected against AGEs-induced mitochondrial dysfunction by significantly mitigating the loss of mitochondrial membrane potential, reduction in intracellular ATP levels, and occurrence of mitochondrial permeability transition in AGEs-treated cells. Fucoidan also markedly suppressed the production of reactive oxygen species and, lipid and protein peroxidation induced by AGEs. In cells exposed to AGEs, gene expression related to osteogenic differentiation and markers of osteogenic activity increased, while markers of osteoclastic activity decreased. Fucoidan significantly moderated these changes. In conclusion, AGEs induce mitochondrial dysfunction and apoptosis in MC3T3-E1 cells, while decreasing osteogenic differentiation and activity, and increasing osteoclastic activity. Fucoidan appears to reduce cellular and mitochondrial damage and improve osteogenic activity impaired by AGEs.

• Journal of dental hygiene science
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• v.12 no.1
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• pp.63-70
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• 2012

The purpose of this study was to research sociodemographic characteristic, work-concerned characteristic, health behavior, life stress, psychosocial stress, job stress and self-esteem of dental hygienists and to find their effects on cortisol level in saliva. The target of this study is 219 dental hygienists registered in Daegu and Gyeongbuk Dental Hygienists Association as of February 2010. For life stress, there was significant difference depending on working years of current job(p<0.05), self health status and regular meal(p<0.01). For psychosocial stress, there was significant difference depending on age(p<0.05), daily working hours(p<0.01), self health status, sleeping hours, regular meal and hobby and leisure activity(p<0.01). For job stress, there was significant difference depending on academic background (p<0.05), job experience, position, man power appropriateness in department and working years of current job(p<0.05). For cortisol level in saliva, extra working days(p<0.05) and self health status(p<0.05) showed significant difference and job stress and cortisol level in saliva showed the negative correlation(p<0.01). Health behavior gave a significant effect to life stress by path coefficient -36.807(p<0.05) and that to psychosocial stress by path coefficient -5.209(p<0.001). And health behavior also gave a significant effect to self-esteem by path coefficient 0.561(p<0.05). Life stress gave a significant effect to psychosocial stress by 0.012(p<0.05) with self-esteem to psychosocial stress by -2.437(p<0.001) and psychosocial stress to job stress by 0.523(p<0.001). Job stress gave a significant effect to cortisol level in saliva by -0.060 (p<0.05). It was found that the most significant factor that affects cortisol level in saliva was job stress, but showed negative correlation. It can be assumed that chromic job stress cause shortage in cortisol excretion, and caused lower cortisol level in saliva.

• Journal of Chest Surgery
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• v.34 no.11
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• pp.809-822
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• 2001

Background: Ischemic preconditioning(IP) is known to be effective in the protection of myocardial necrosis, arrhythmia, and the restoration of the myocardial function in the ischemia-reperfusion state of the heart. However the exact mechanism is not clearly understood. The purpose of this study was to elucidate the trigger mechanism 7f IP on the restoration of the myocardial function after ischemia-reperfusion. Material and Method: By connecting a Langendorff perfusion apparatus with an isolated heart of a rat, the normal temperature of the heart was maintained. The experiment was conducted in seven groups, which were divided according to the preconditioning stimuli and blockage methods Group I(n=10) was a group without IP, Group II(n=10) a group of three-minute IP, Group III(n=10) a group of PEIP, Group IV(n=10) a group of clonidine IP, Group V(n=10) a group of If after reserpine, Group Vl(n=10) a group of PE & prazosin IP, and Group Vll(n=10) a group of clonidine & yohimbine IP. Hemodynamic parameters of DP, LVEDP, $\pm$dP/dT and the changes of perfusion in the coronary artery were evaluated. Result: Developed pressure and +dP/dT changed per unit time. After 20 minutes of reperfusion, those of Group II and III were 63.1$\pm$3.7%, 64.8$\pm$4.6% and 64.5$\pm$4.6%, 63.8$\pm$4.4%, which improved more significantly than those of Group I(P<0.05), However, there were no significant differences between the Groups V and Vl, and Group I. Conclusion: The Brief ischemic preconditioning and pharmacological preconditioning using $\alpha$-receptor sympatho-mimetics have protecting effects on the restoration of myocardial function after reperfusion. And the protecting effect of preconditioning seems to be related to sympathetic neurotransmitters and to the selective action of the $\alpha$$_1$-adrenergic receptor.

• Journal of Chest Surgery
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• v.30 no.9
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• pp.899-907
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• 1997

Recently, primary lung cancer has increased markedly in incidence & prevalence in korea. Prom July 1979 to June 1996, 183 patients were diagnosed and operated for primary non-small cell lung cancer, and evaluated clinically. 1. There were 164 males and 19 females(M:P=8.6: 1), and the peak incidence of age was 50th and 60th decade of life(73.7%). 2. Most of symptoms were respiratory, whitch were cough(44.8%), chest pain(30.1%), dyspnea(20.8%), hemoptysis or blood tinged sputum(19.7%), sputum(15.3%), and asymptomatic cases were 12.0%. 3. Histopathologically, sguamous cell carcinoma was 68.9%, adenocarcinoma 19.7%, bronchioloalveol r cell carcinoma 2.2%, adenosguamous cell carcinoma 1.6%, and large cell carcinoma 7.7%. 4. In the operation, pneumonectomy was 41.0%, lobectomy 42.1%, bilobectomy 13.1%, stagmentectomy or wedge resection 1.6%, and explore tharacotomy 2.2%, and the overall resectability was 97.8%. 5. Postoperative complications were developed in 31.9%, and operative mortality was 1.6%. 6. In postoperative stagings, stage I was 38.3%, stage H 14.8%, stage llla 31.1%, and stage IIIb 15.8%. 7. The overall cumulative survival rates were 1 year 77.8%, 3 year 42.7%, and 5 year 39.5%. The 5 year survival rate according to stage were stage 153.0%, stage H 46.5%, stage I[la 28.2%, and stage IIIb 13.8%(p<0.05), according to operation method were lobectomy 45.0%, and pneumonectomy 30.3%(p<0.05), and according to mediastinal involvement were Nl 32.0%, and N2 11.1%(p<0.05). The 5 year survival rate according to histologic type were squamous cell carcinoma 43.1%, adenocarcinoma 23.3%, and large cell carcinoma 30.3 (p>0.05).

• Journal of Chest Surgery
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• v.30 no.9
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• pp.854-861
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• 1997

CYPRA 21-1 is known to be a cytokeratin 19 fragment, and it can be detected by using two specific monoclonal antibodies (KS 19-1 and BM 19-21) and can be clinically applied as a useful circulating tumor marker The epidermal growth factor receptor (EGF-R) expression was evaluated and characterized by its tyrosine protein kinase activity and by its ligand-stimulated autophosphorylation, a property shared with other peptide growth factor receptors. Autocrine or para'urine action was initiated by a growth factor, or by a transforming growth factor o, which had an extensive homology with EGP and which also stimulated tyrosine kinase activity on the EGF-R. The CYFRA 21-1 and the EGF-R levels in 30 patients with primary lung tumors were investigated. There were 24 patients with squamous cell carcinomas and 6 patients with adenocarcinomas. Specimen 5 mm3 in size were sampled at three different locations ; the main lesion, the boundary between the lesion and the unaffected tissue, and the unaffected tissue of the patients. The results were as follows 1. The CYPRA 21-1 concentration in the cancer boundary, the most malignant region,(348.6 : 89.9 ng/ml) was the lowest value. The CYFRA 21-1 concentration in unaffected tissue,(718.4$\pm$77.8 ng/ml) was higher than that in the main lesion. which had intact cellularity. 2. The EGF-R concentration in the main lesion was higher than that in the unaffected tissue, and the EGF-R concentration in a squamous cell cacinoma was higher than that in an adenocarcinoma. also, the EGF-R concentration in the cancer b undary was highest at stage 1, ll. The EGF-R concentration was higher in the main cancer lesion that in the unaffected tissue at stage 111, IV. 3. The CYFRA 21-1 was a cytoplasmic skeleton and the EGF-R was a cell-wall component; there was no correlation. In conclusion, CYFRA 21-1 was abundant in the cytoplasm but had a higher concentration in the unaffected tissue than in the main cancer lesion. The CYFRA 21-1 concentration of the tissue did not reflect the amount of cancer activity, the EGP-R was located in the cell membrane, the level of tissue that reflects cancer activity, so the main cancer lesion had a higher concentration than the unaffected tissue. CYFRA 21-1 is not a useful tumor maker at the tissue level. Because the EGF-R concentration re(looted the cancer activity, its a useful tumor marker for lung cancer.

• The Korean Journal of Pharmacology
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• v.24 no.1
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• pp.103-109
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• 1988

Cyclobuxine D, extracted from Buxus microphylla var. koreana Nakai, is a steroidal alkaloid. Many pharmacological effects of cyclobuxine D were examined in our Lab. Cyclobuxine D showed a significant bradycardic effect in the rat heart and an inhibitory action on acetylcholine and $Ba^{++}-induced$ contraction of the longitudinal muscle isolated from the rabbit jejunum. In this study, we investigated the effect of cyclobuxine D on the contractile response-elicited by acetylcholine, oxytocin and $Ba^{++}$ in rat uterine. In order to analyse the inhibitory action of cyclobuxine D on the smooth muscle, we examined the inhibitory action of cyclobuxine D against the contractile response of the high potassium-depolarized rat ileum to calcium. Concentration-dependent decrease in the peak tension and duration of the acetylcholine, oxytocin and $Ba^{++}-induced$ contraction in the isolated rat uterus was observed when cyclobuxine D was added to the organ bath. The isolated longitudinal muscle from the rat ileum was immersed calcium-depleted potassium-depolarizing solution. Ten minutes after, 1.8 mM $CaCl_2$ was added to muscle bath and elicited a biphasic increase in muscle tension. Cyclobuxine D $(6.2{\times}10^{-5}\;M)$ produced an appreciable inhibition of both components of the mechanical response. In addition, $3.1{\times}10^{-4}\;M$ cyclobuxine D, introduced at a point when the tonic response had reached its maximum level, caused the muscle to exhibit a rapid lose of tension. Based on these experimental results, we propose the possibility that the inhibitory action of cyclobuxine D on the acetylcholine, oxytocin and $Ba^{++}-induced$ contraction in the isolated rat uterus may be due to blocking potassium-activated calcium channels, voltage-sensitive calcium channels.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.2
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• pp.195-201
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• 2014

Body fluid has been studied for diverse fields like Ringer's solutions, artificial joint fluids, cell growth culture media because it plays a crucial role in controlling body temperature and acts as a solvent for diverse metabolite processes in the body and delivery media of mineral, energy source, hormone, signal and drug from and to cell via blood or lymphatic vessel by osmotic pressure or active uptake. Stratum corneum containing extracellular lipids and NMF (natural moisturizing factor) absorbs atmospheric water residing outside of cells and utilize it to hydrate inside of their own. This process is related to skin barrier function. In this study, we conducted the cell viability test with Cell Bio Fluid $Sync^{TM}$, which mimicks body fluids including amino acids, peptides, and monosaccharides to strengthen skin barrier, and the clinical skin improvement test with cosmetics containing Cell Bio Fluid $Sync^{TM}$. In the cell viability test, HaCaT cell was treated with PBS for 3 hours, followed by the treatment of a cell culture medium (DMEM) and isotonic solution (PBS) and Cell Bio Fluid $Sync^{TM}$ for 3 hours each. Then, MTT assay and image analysis were conducted. In the clinical skin improvement test, twenty-one healthy women participated. Participants applied cosmetics containing Cell Bio Fluid $Sync^{TM}$ on their face for a week and evaluated the skin hydration, skin roughness, brightness and evenness. All measurements were conducted after they washed off their face and took a rest under the constant temperature ($22{\pm}2^{\circ}C$) and constant humidity conditions ($50{\pm}5%$) for 20 minutes. All the data were analyzed by SPSS (version 21) software program. Results showed that Cell Bio Fluid $Sync^{TM}$ improved both the cell viability and in vivo skin conditions such as skin hydration, roughness, brightness and evenness.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.53-68
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• 1997

Lake Shihwa, artificially constructed since 1988, shows a typical two-layered system depending on strong haline density stratification. Sill of the water gate at 6 m depth greatly restricts physical mixing with outer seawater and circulation in the lake, and contributes to the enhancement of anoxic environment in the deeper layer. With this enclosed physical environment, Lake Shihwa receives enormous amounts of organics, ammonia, and other pollutants from the neighboring municipal and industrial complexes through six major streams, thus developing biogeochemical differentiation of anoxic to suboxic environment in the high saline bottom water and highly eutrophicated brackish surface water. This study investigated vertical structures, biogeochemical behaviors and processes of various organic and inorganic compounds around oxic-anoxic interface. Nitrite and nitrate rapidly decreased below the pycnocline where about $1{\times}10^8$ tons of hypoxic bottom water exist. In this bottom layer, ammonium ranged from 75 to 360 ${\mu}M$ mainly resulting from deamination of dissolved organic nitrogen and ammonification of precipitated organic particles. Despite large amounts of surface water discharge and dilution by outer seawater inflow about $3{\times}10^8$ tons from April to August, 1996, bottom layer did not show any improvement of water quality and maintained highly reduced environment. The main reason seems to be imbalance between ineffectiveness of dilution due to shallow depth and large surface area, overloaded POC influx from the eutrophicated surface biological activity, and poor replenishment of oxygen in this artificial lake system. Therefore, as long as current salinity dependent two-layered system maintains with its physical limitations, any improvement of water quality cannot be foreseen in Lake Shihwa.