• 한국지반공학회논문집
• /
• 제20권5호
• /
• pp.49-58
• /
• 2004

시화지역 퇴적층의 퇴적환경을 분석하여 압밀특성을 연구하였다. 퇴적환경은 입도분석, 퇴적구조, 지화학특성, 간 극수 화학분석, 탄소동위원소분석을 통해 분석하였으며 조사지점에서 연속적으로 채취한 불교란 시료에 대해 압밀시험과 이방압밀삼축시험(CKoUC)을 수행하여 과압밀현상을 조사하였다. 퇴적환경 분석 결과 상부의 실트/점토 혼합층은 해성환경에서 퇴적되었으며 하부의 모래층과 점토층은 하성환경에서 퇴적된 것으로 밝혀졌다. 해성퇴적층에서는 실트와 점토의 수평층리에 의한 퇴적구조가 우세하게 나타난다. 해성퇴적층 내에서 지질학적 침식이 발생했다는 뚜렷한 증거가 없음에도 불구하고 상부 해성퇴적층의 과압밀비는 1보다 크게 나오고 있다. 상부 해성퇴적층은 삼축 응력경로에서 정규압밀 점토와 동일한 거동을 보이며, 응력상태선도에서도 지질학적 의미의 정규압밀 영역에 도시된다. 해성퇴적층의 이러한 겉보기 과압밀 현상은 퇴적속도의 차이에 의해 발생되는 연약층의 구조, 즉 입자간 화학적 결합력에 의해 발생된 것으로 설명할 수 있다.

• Biomolecules & Therapeutics
• /
• 제29권5호
• /
• pp.545-550
• /
• 2021

Chemotherapy-induced alopecia and hair loss can be stressful in patients with cancer. The hair grows back, but sometimes the hair tends to stay thin. Therefore, understanding mechanisms regulating hair regeneration may improve the management of chemotherapy-induced alopecia. Previous studies have revealed that chemotherapeutic agents induce a hair follicle vascular injury. As hair growth is associated with micro-vessel regeneration, we postulated that the stimulation of angiogenesis might enhance hair regeneration. In particular, mice treated with 5-fluorouracil (5-FU) showed delayed anagen initiation and reduced capillary density when compared with untreated controls, suggesting that the retardation of anagen initiation by 5-FU treatment may be attributed to the loss of perifollicular micro-vessels. We investigated whether the ETS transcription factor ETV2 (aka ER71), critical for vascular development and regeneration, can promote angiogenesis and hair regrowth in a 5-FU-induced alopecia mouse model. Tie2-Cre; Etv2 conditional knockout (CKO) mice, which lack Etv2 in endothelial cells, presented similar hair regrowth rates as the control mice after depilation. Following 5-FU treatment, Tie2-Cre; Etv2 CKO mice revealed a significant reduction in capillary density, anagen induction, and hair restoration when compared with controls. Mice receiving lentiviral Etv2 injection after 5-FU treatment showed significantly improved anagen induction and hair regrowth. Two-photon laser scanning microscopy revealed that enforced Etv2 expression restored normal vessel morphology after 5-FU mediated vessel injury. Our data suggest that vessel regeneration strategies may improve hair regrowth after chemotherapeutic treatment.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
• /
• pp.103.3-104
• /
• 2003

Activation of hepatic stellate cell has been identified as a critical step in hepatic fibrogenesis and is regulated by several factors including cytokines and oxidative stress. In this study, we assayed effects of saponin (CKS), inulin (CKI) and oligo-sugars (CKO) isolated from Platycodon grandiflorum A. DC, changkil (CK) on experimental cell cycle arrest and apoptosis in hepatic stellate cell line (HSC-T6). CKS induced cell arrest at G$_1$. CKS also reduced intercellular reactive oxygen species and collagen synthesis in hydrogen peroxide-induced oxidative stress and acetaldehyde-stimulated collagen synthesis, respectively, in HSC-T6 cells. (omitted)

• 대한설비공학회지:설비저널
• /
• 제15권2호
• /
• pp.188-195
• /
• 1986

Condensation heat transfer can be classified in dropwise condensation and filmwise condensation, and for the industrial purpose, the former is more useful than the latter because of the higher heat transfer rate. But it is difficult to maintain the dropwise condensation continuously since most of the metal surfaces become wetted after exposure to a condensing vapor over an extended period of time. To maintain dropwise condensation continuously , various surface coatings and promoters have been used recently, but these methods must be reconsidered about the durability of condensing surface. Therefore, in this study, evaporating method of various pure metals on the condensing surface has been performed to maintain dropwise condensation. The results have showed that the heat transfer rate of silver evaporating surface is higher than any other metal evaporating in dropwise area. Transition temperature and filmwise condensation curves are uniform regardless of kinds of evaporating metals.

• 펄프종이기술
• /
• 제31권4호
• /
• pp.49-57
• /
• 1999

In CLO2 delignification and bleaching process, formation of chlorate corresponds to a loss of 20-36% of the original CKO2 charge. Because chlorate is inactive and harmful to environmental, it will be of benefit to find methods that can reduce the formation of chlorate during chlorine dioxide bleaching. Chlorate is mainly formed by the reaction HCIO +ClO2 $\longrightarrow$H+ + Cl_ +ClO3-2 On the other hand, AOX in chlorine dioxide bleacing is formed also due to the in-situ produced hypochlorous acid. THus both AOX and chlorate could be reduced by addition of hypochlorous acid. Some paper son the reduction of AOX by additives appeared , but systematic data on chlorate reduction as well as pulp and effluent properties are not available. THus this paper of focused on the effects on the reduction of chlorate and chlorine dioxide bleachability. The additives, fulfamic a챵, AMSO, hydrogen peroxide, oxalic acid were found to eliminate chlorine selectively in chlorine and chlorine dioxide mixture.However, when they were added to bleaching process, sulfamic acid and DMSO showed significant reduction of chlorate formation but hydrogen peroxide and oxalic aicd did not, and significant amount ofhydrogen peroxide was found resided in the bleaching effluent , In addition, sulfamic acid and DMSO decreased the bleaching end ph values while hydrogen peroxide and oxalic acid did not, which also indicated that hydrogen peroxide and oxalic acid were ineffective. The difference might be ascribed to the competitives of hypochlorous acid with lignin, chlorite (CKO2) and additives. Sulfamic acid and DMSO showed better pulpbrightness development but less alkaline extraction efficiency than hydrogen peroxide , oxalic acid and control, which means that insitu hypochlorous acid contributes to the formation of new chromophore structures that can be easily eliminated by alkaline extraction. DMSO decreased the delignification ability of chlorine dioxide due to the elimination of hypochlorous acid, but sfulfamic acid did to because the chlroinated sulfamic acid had stable bleachability. In addition, sulfamic acid, and SMSO shwed decreased color and COD of bleaching effluents, hydrogen peroxide decreased effluent color but not COD content, and oxalic acid had no statistically significant effects. No significant decreases of pulp viocosity were found except for hydrogen peroxide. Based on our results , we suggest that the effectiveness of hydrogen peroxide on the reduction of AOX in literature might be explained by other mechanisms not due to the elimination of hypochlorous acid , but to the direct decomposition of AOX by hydrogen peroxide.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2004년도 춘계학술발표회
• /
• pp.203-210
• /
• 2004

Consolidation properties were analysed by means of depositional environments. Depositional environments including geochemical properties, porewater chemistry, sediment structures, particle size distributions and carbon age dating were analysed using undisturbed samples retrieved successively from a boring hole in the study area. Laboratory oedometer tests and anisotropic consolidated triaxial tests(CKoUC) were performed to examine the overconsolidation phenomenons. Based on the carbon age dating results and profiles of geochemical properties, porewater chemistry, salinity and pH, it was founded that the upper silt/clay complex layer was deposited under marine condition while sand and clay layers were deposited under fluvial condition. Planar laminated structures of silts and clays were dominant in marine deposits. Although there was no clear evidences that geological erosion had been occurred in marine deposits, overconsolidation ratio obtained from oedometer tests were greater than unity. Stress paths of samples behaved similar to those of normally consolidated clays. Data plotted in stress state charts proposed by Burland(1990) and Chandler(2000) showed that the marine deposits were geologically normally consolidated. These apparent overconsolidations can be explained by the fabric and chemical bonding due to the difference of the rate of deposition.

• 한국병원경영학회지
• /
• 제6권1호
• /
• pp.18-40
• /
• 2001

This study purports to investigate the readiness of the university hospital employees in the knowledge-based management. Data were collected from 550 employees including administrative, nursing, and technical staff of 9 university hospitals located in Seoul and Kyunggi Province through the self-administered questionnaires. The response rate was 79% and 425 questionnaires were used as final data and analyzed using 2 test, t-test, and ANOVA. The main findings of the study are as follows. 1) It seems that most employees of the study hospitals have basic knowledge on the concept of knowledge-based management. This finding implies that the implementation of the knowledge-based management in Korean university hospitals will not likely to face strong resistance from their employees. 2) The results show that Korean hospital employees are still not so accustomed to using e-mail as the main communication tool. This finding suggests that it is necessary to use various communication tools which include electronic data interchange, teleconference, and cyber chatting for facilitating the knowledge-based management in Korean university hospitals. 3) It is desirable to appoint a chief knowledge officer(CKO) for operating knowledge-based management system effectively. 4) A reward system for employees who show a distinguished performance in the creation and sharing of new knowledge should be established. Knowledge mileage system, selection of the best knowledge employee and team will be a good example of the effective reward system. 5) The participation and support from the chief executive officers (CEO) of the hospitals is an important factor for successful knowledge-based management. Furthermore, to make physicians actively participate in the knowledge-based management is another important factor for obtaining valuable outputs from the system. 6) It is found that the knowledge and skills of the hospitals employees on the information technology (IT) are not sufficient for making knowledge-based management more popular. This implies that it is very important to select IT-oriented employees and educate them continuously on the knowledge-based management.

• 한국지반공학회논문집
• /
• 제21권4호
• /
• pp.31-40
• /
• 2005

본 연구에서는 이방성을 가지는 현장지반의 비배수 전단거동을 예측하기 위해 한계상태 간격비를 고려한 새로운 항복함수식을 제안하였다. 또한 수정 Cam-clay모델의 항복면 식을 이방압밀 조건에 적용할 수 있도록 수정한 새로운 소성포텐셜 함수를 적용하는 비관련 구성모델을 제안하였다. 제안모델을 적용하여 등방 및 이방압밀된 재성형 포항 이암풍화토의 비배수 전단거동을 예측하였으며, 신뢰성을 평가하기 위해 등방정규압밀된 Bankok clay 및 $K_0$ 압밀된 Drammen clay의 비배수 전단거동을 예측하였다. 그 결과 제안된 모델은 전반적인 거동을 잘 예측하는 것으로 나타났다.