• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.06a
• /
• pp.68-69
• /
• 2020

Recently, the problem of air pollution is drawing attention as a social problem worldwide. Particularly, fine dust is the biggest issue among air pollutants, and it is analyzed that fine dust is generated from air pollutants such as burning fossil fuels such as petroleum or coal, or exhaust gases from automobiles. In addition, yellow dust originating from China adjacent to Korea flows into the Korean Peninsula in a western wind, causing the concentration of fine dust to deteriorate. Fine dust is a harmful substance to the human body such as asthma or respiratory disease, and awareness of the risk is also increasing to a degree designated as a primary carcinogen. In this study, as a method for improving the indoor air quality, the Properties of the matrix according to the mixing ratio of powdered activated carbon based on blast furnace slag are reviewed. The flexural strength and compressive strength were measured, and a fine dust concentration measurement experiment will be conducted later.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.1
• /
• pp.65-73
• /
• 2007

In the inverse perturbation method, enormous computational resource was required to obtain reliable results, because all unspecified DOFs were considered as unknown variables. Thus, in the present study, a reduced system method is used to condense the unspecified DOFs by using the specified DOFs, and to improve the computational efficiency as well as the solution accuracy. In most of the conventional reduction methods, transformation errors occur in the transformation matrix between the unspecified DOFs and the specified DOFs. Thus it is hard to obtain reliable and accurate solution of inverse perturbation problems by reduction methods due to the error in the transformation matrix. This numerical trouble is resolved in the present study by adopting iterative improved reduced system(IIRS) as well as by updating the transformation matrix at every step. In this reduction method, system accuracy is related to the selection of the primary DOFs and Iteration time. And both are dependent to each other So, the two level condensation method (TLCS) is selected as Selection method of primary DOFs for increasing accuracy and reducing iteration time. Finally, numerical verification results of the present iterative inverse perturbation method (IIPM) are presented.

• Molecules and Cells
• /
• v.43 no.11
• /
• pp.945-952
• /
• 2020

Hypoxia induces the expression of several genes through the activation of a master transcription factor, hypoxia-inducible factor (HIF)-1α. This study shows that hypoxia strongly induced the expression of two carboxypeptidases (CP), CPA4 and CPE, in an HIF-1α-dependent manner. The hypoxic induction of CPA4 and CPE gene was accompanied by the recruitment of HIF-1α and upregulation in the active histone modification, H3K4me3, at their promoter regions. The hypoxic responsiveness of CPA4 and CPE genes was observed in human adipocytes, human adipose-derived stem cells, and human primary fibroblasts but not mouse primary adipocyte progenitor cells. CPA4 and CPE have been identified as secreted exopeptidases that degrade and process other secreted proteins and matrix proteins. This finding suggests that hypoxia changes the microenvironment of the obese hypoxic adipose tissue by inducing the expression of not only adipokines but also peptidases such as CPA4 and CPE.

• Journal of the Korean Society for Heat Treatment
• /
• v.22 no.1
• /
• pp.8-15
• /
• 2009

Structural studies have been performed on precipitation hardening found in $Ni_{3}Al$ based ordered alloys using transmission electron microscopy (TEM). Tilt experiments by the weak-beam method were made to obtain some information concerning the cross slip mechanism of the superlattice dislocation. The strength of ${\gamma}'-Ni_3$(Al,Ti) increases over the temperature range of experiment by the precipitation of fine $\gamma$ particles. The peak temperature where a maximum strength was obtained shifted to higher temperature. Over the whole temperature range, the interaction between dislocation and $\gamma$ precipitates is attractive. On the temperature range of 773 K to 973 K, the dislocations in ${\gamma}'$ matrix move on (111) primary slip plane. When the applied stress is removed, the dislocations make cross slip into (010) plane, while those in $\gamma$ precipitates remain on the (111) primary slip plane. The increase of high temperature strength in ${\gamma}'-Ni_3$(Al,Ti) containing $\gamma$ precipitates is due to the restraint of cross slip of dislocations from (111) to (010) by the dispersion of disordered $\gamma$ particles.

• Journal of Chest Surgery
• /
• v.24 no.8
• /
• pp.802-806
• /
• 1991

Primary neoplasms of the ribs and sternum are rare. Most primary bony chest wall neoplasms are malignant, and chondrosarcoma is the most common malignancy in this location The etiology of chondrosarcoma is unknown. Definitive diagnosis of chondrosarcoma can only be made pathologically. The natural history of chest wall chondrosarcoma is one of slow growth and local recurrence. Most tumors of the sternum require wide resection and reconstruction procedures, with potentially serious postoperative problems. Advances in chest wall reconstruction primarily through refinement in muscle transposition and clarification of the functional anatomy and blood supply of trunk muscles, has resulted in a more aggressive resection of the these tumors . Recently we experienced a case with chondrosarcoma of the sternum. A 56 year-old man was admitted to our hospital due to painless, slowly enlarging mass at the left sternoclavicular junctional area. The chest radiograph strongly suggested an underlying cartilaginous neoplasm owing to the appearance of typical flocculent and curvilinear calcifications within the lesion. On CT of the chest, the tumor exhibited a scalloped or lobulated contour, hypodensity of the nonmineralized component in comparison to adjacent muscle, and characteristic stippled cartilaginous matrix mineralization, also typical for cartilaginous neoplasm. The patient underwent wide resection of the chest wall tumor include with a 2-3cm margin of normal tissue on all sides and the thoracic skeletal defect was reconstructed with polytetrafluoroethylene [Gore-Tex] soft-tissue patch. Soft tissue reconstructive procedure was done with the pectoralis major muscle transposition. The patient had an uneventful postoperative course and discharged without adjuvant treatment such as radiation and chemotherapy.

• 한국생물공학회:학술대회논문집
• /
• 2000.11a
• /
• pp.421-424
• /
• 2000

Cartilage injuries are frequent nowadays. The previous surgical treatment of cartilage defect was limited. Another approach in the treatment of cartilage injuries is the use of reconstitute cartilage consisting of chondrocytes cultured in suitable biodegradable scaffolds. Current studies have demonstrated the compatibility of chondrocytes with different biomaterials and the chondrogenesis in various types of porous scaffolds. The cell ingrowth into the porous scaffolds is modulated by initial cell loading efficiency. Therefore, well-interconnected pore structure and even pore distribution of the scaffolds are essential for efficient cell seeding. According to our previous work, well-interconnected macroporous scaffolds can be prepared by gas-foaming/salt-leaching method using ammonium bicarbonate salt as porogen additives. In this work, primary chondrocytes were cultured in PLGA 65/35 scaffolds fabricated by using our method. Cells seeded in the scaffolds showed well distribution by agitated seeding method. Histochemical staining of proteoglycans present in the scaffolds was used to visualize the chondrocyte ingrowth in the scaffolds. At 3 weeks, the population of chondrocytes was increased for the most part of the scaffolds, and extra cellular matrix (ECM) secretion was increased as culture periods progressed.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.41-41
• /
• 2011

Flash memory에서 tunnel oxide film은 electron tunnelling 현상을 이용하여 gate에 전하를 전달하는 통로로 사용되고 있다. 특히, tunnel oxide film 내부의 charge trap 현상과 불순물이 소자 특성에 직접적인 영향을 주고 있어, 후속 N2O/NO 열처리 공정에서 SiO2/Si 계면에 nitrogen을 주입하여 tunnel oxide film 특성을 개선하고 있다. 따라서 N2O/NO 열처리 공정 최적화를 위해서는 tunnel oxide film 내 N 농도와 분포에 대한 정확한 평가가 필수적이다[1]. 본 실험에서는 low energy magnetic SIMS를 이용하여 N2O로 열처리된 tunnel oxide film 내의 N농도를 보다 정확하게 평가하고자 하였다. 사용된 시료는 Si substrate에 oxidation 이후 N2O 열처리를 진행하여 tunnel oxide를 형성시켰으며, 분석 impact energy는 surface effect최소화와 최상의 depth resolution 확보를 위해 250eV를 사용하였으며, matrix effect와 mass interference를 방지하기 위해 MCs+ cluster mode[2]로 CsN signal를 검출하였다. 실험 결과, 특정 primary beam 입사각도에서 nitrogen depth resolution 저하 현상이 발생하였고, SIMS crater 표면이 매우 거칠게 나타났다. 이에, Depth resolution 저하 현상을 개선하기 위해 극한의 glancing 입사각 조건으로 secondary extraction voltage 변화를 통해 depth resolution이 개선되는 최적의 impact energy와 primary beam 입사각 조건을 확보하였다. 그 결과 nitrogen의 depth resolution은 1.6nm의 depth resolution을 확보하였으며, 보다 정확한 N 농도와 분포를 평가할 수 있게 되었다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.994-995
• /
• 2006

The microstructure of the extruded Al-20Si bars showed a homogeneous distribution of eutectic Si and primary Si particles embedded in the Al matrix. The grain size of ${\alpha}-Al$ varied from 150 to 600 nm and the size of the eutectic Si and primary Si in the extruded bars was about 100 - 200 nm. The room temperature tensile strength of the alloy with a powder size $<26{\mu}m$ was 322 MPa, while for the coarser powder ($45-106{\mu}m$) it was 230 MPa. With decreasing powder size from $45-106{\mu}m$ to $<26{\mu}m$, the specific wear of all the alloys decreased significantly at all sliding speeds due to the higher strength achieved by ultrafine-grained constituent phases. The fracture mechanism of failure in tension testing and wear testing was also studied.

• Journal of Korean Foot and Ankle Society
• /
• v.23 no.1
• /
• pp.31-34
• /
• 2019

Chondroblastoma is a rare benign tumor that produces giant cells and cartilage matrix. The tumor occurs in people between 10 and 25 years with slightly higher incidence in males. The condition occurs in the proximal epiphysis of the tibia and humerus, distal epiphysis of the femur, but its occurrence in the talus is relatively rare, accounting for 4% of the total number of chondroblastoma cases. Chondroblastoma is often misdiagnosed as a primary aneurysmal bone cyst, giant cell tumor, chondromyxoid, and lesion of a secondary aneurysmal bone cyst by fibrous dysplasia. The most commonly used surgical method for chondroblastoma is broad curettage with bone grafting. In general, an aneurysmal bone cyst is associated with a second degree chondroblastoma, which is approximately 20%. Chondroblastoma of the talus and secondary aneurysmal bone cysts can be misdiagnosed as primary aneurysmal bone cysts. This paper reports a case of a young male patient with chondroblastoma of the talus, which was initially misdiagnosed as an aneurysmal bone cyst with involvement of the talo-navicular joint.

• Journal of Korean Foot and Ankle Society
• /
• v.27 no.2
• /
• pp.71-74
• /
• 2023

A medial opening wedge supramalleolar osteotomy (SMO) introduced by Takakura et al. is a useful realignment procedure for patients with ankle joint arthritis and varus malalignment by shifting the weight-bearing axis laterally and redistributing the loads on the ankle joint. When pain persists after arthroscopic microfracture in patients with medial osteochondral lesion of the talus (OLT), redo arthroscopy, osteochondral autograft transplantation, autologous chondrocyte implantation, or matrix-induced chondrogenesis might be indicated. On the other hand, there is insufficient scientific evidence for realignment surgery through SMO, while the effect of realignment surgery has been studied consecutively for osteochondral lesions of the knee. Therefore, this paper reports a patient with medial OLT who underwent redo arthroscopy combined with SMO for persistent pain after primary arthroscopic microfracture.