• Title/Summary/Keyword: 천공수

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Case Studies and Future Prospect of Using Bulk Emulsion (에멀젼계 벌크폭약을 이용한 시공사례와 향후 전망)

  • Kim, Hee-Do;Choi, Sung-Hyun
    • Explosives and Blasting
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    • v.26 no.2
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    • pp.64-76
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    • 2008
  • Bulk Emulsion blasts using mechanized charging system, which is generally used in foreign countries, have recently introduced and gradually increased in Korea. The Bulk Emulsion are safe and able to increase the charging density for improvement of fragmentation and advancement especially in tunneling, and minimizing environmental problem. Because of less toxic gas generation, the explosives are called, namely ech-friendly products. There are two kinds of Bulk Emulsion; one is for open cut and the other is for tunneling. According to features of blast sites and its purpose, the compositions are different, but the principle is the same. In this study, trial blasts using Bulk Emulsion for tunneling had executed at 10 sites in Korea. The major result of the major job-sites is the following. First of all, compared with cartridge explosive, Bulk Emulsion was able to increase its charging density up to $35{\sim}60%$, to decrease the blast holes to approximately $10{\sim}30%$ down, and the advancement was improved up to $8{\sim}20%$ and also 30% up in its fragmentation. Toxic gas production after cartridge blasting showed 34.44ppm of its CO. Bulk Emulsion, however, showed 20.13ppm, which was 58.45% production of the cartridge explosive, and NOx was below 2ppm. The mechanized charging system of Bulk Emulsion should be applied to large sized tunnel blasting, long advanced tunnel which can secure the advancement of over $4{\sim}5m$, and the sites required finishing rapidly.

A Clinical Study of Hearing Disturbance and Middle Ear Pathology in Chronic Otitis Media (만성중이염의 교실내 병변과 청력에 관한 임상적 연구)

  • 박동석;전재기
    • Proceedings of the KOR-BRONCHOESO Conference
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    • 1979.05a
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    • pp.4.4-5
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    • 1979
  • The degree of hearing impairment of chronic otitis media will indicate the nature and severity of middle ear pathology especially condition of ossicular chain, size of ear drum perforation and location of granulation tissue in the middle ear cavity. The subjects were 189 ears of tympanoplasty for chronic otitis media and divided into four groups as follows: Normal ossicular chain with only ear drum perforation (group I), normal ossicular chain with granulation tissue only around the ossicles regardless of any other region (group II), ossicular ankylosis or fixation of handle of malleus to promontory with or without granulation tissue around the ossicle (group III) and ossicular interruption by partial or complete destruction(groupf IV). The results were concluded as follows: 1) The average hearing threshold of chronic otitis media was 44.6 dB and hearing threshold was closely related to the condition of ossicular chain. Hearing threshold became greater in order of normal ossicular chain, ankylosis and interruption. 2) The average hearing threshold of ossicular interrupted group was 49.1 dB and it was greater in the cases of total destruction than that of partial destruction. 3) The hearing loss in the cases of normal ossicular chain with only tympanic membrane perforation was within 45 dB and this level was presumed to represent normal ossicular function. The degree of hearing loss was in proportion to the size of ear drum perforation and when over 45 dB, other middle ear pathology was suggested. 4) In the cases of small ear drum perforation with normal ossicular function, the hearing threshold was within 30 dB. 5) In the type of audiogram, flat type was 30.2% and ascending type 35.4%. Descending type was more frequent in the cases of normal ossicular mobility with granulation tissue around the ossicle and flat type was observed frequently in the cases of ossicular ankylosis. 6) Carhart's notch was seen in 14 cases (7.4%) and observed mainly in ossicular ankylosis. 7) There was no relation between hearing threshold and histopathological type of granulation tissue in chronic otitis media. However the degree of hearing impairment was related to the location of granulation tissue in the middle ear cavity. 8) Authors recognized the granulation tissue compensated the function of interrupted ossicular chain.

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Clinical Results of Anterolateral Thigh Perforator Flap for Soft Tissue Reconstruction of the Foot and Ankle (족부 및 족관절부 연부조직 재건을 위한 전외측 대퇴 천공지 피판술의 임상결과)

  • Han, Soo-Hong;Hong, In Tae;Lee, Yohan;Jo, Yong-Gil;Kwon, Young Woo
    • Journal of the Korean Orthopaedic Association
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    • v.52 no.1
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    • pp.40-48
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    • 2017
  • Purpose: Soft tissue reconstruction of a defect around the foot and ankle is a particularly challenging procedure due to the anatomical and functional characteristics of this area. Hence, only a limited number of treatment options are available. Moreover, if patients wish to avoid additional scars on the ipsilateral lower leg for cosmetic reasons, even fewer options are available for treatment. The authors used an anterolateral thigh perforator flap for soft tissue defects in this area, when other surgical options were inadequate. The aim of this study was to report the clinical results and the efficacy of this procedure. Materials and Methods: Sixteen cases of soft tissue defects around the foot and ankle were included. Participants included 12 male and 4 female subjects, and the mean age was 34 years. The most common cause of defect was acute trauma, and the average follow-up period was 33 months. Flap survival time, surgical complications, and ambulation status at the final follow-up stage were evaluated. Results: All 16 flaps successfully survived, except for one case with partial flap necrosis that was thought to be due to weight bearing earlier than scheduled. All patients were able to walk independently without any aid at the final follow-up stage. No patients showed other significant surgical complications. Conclusion: The anterolateral thigh perforator flap is a good alternative for soft tissue defects of the foot and ankle, when other options are not applicable. This study also demonstrated that surgery using an anterolateral thigh perforator flap is safe and highly reliable.

A Numerical Study for Calculation of Overall Heat Transfer Coefficient of Double Layers Covering and Insulation Material for Greenhouse (온실용 이중피복 및 보온재의 관류열전달계수 산정을 위한 수치적 연구)

  • Lee, Jong-Won;Kim, Dong-Keon;Lee, Hyun-Woo
    • Current Research on Agriculture and Life Sciences
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    • v.33 no.2
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    • pp.41-47
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    • 2015
  • This study calculated the overall heat transfer coefficient (U-value) of greenhouse covering materials with thermal screens using a simulation model and then estimated the validity of the calculated results by comparison with measured values. The U-value decreased gradually as the thickness of the air space between the double glazing increased, and then remained essentially constant at thicknesses exceeding 25 mm. The U-value also increased with the difference in temperature between the inside and outside of the hot box. The vigorous convective heat transfer between two plastic films caused unsteady heat flow and then created a nonlinear temperature distribution in the air space. The distance did not affect the U-value at distances of 50~200 mm between the plastic covering and thermal curtain. The numerical calculation results, with and without sky radiation, were in accord with the experimental results for a $30^{\circ}C$ temperature difference between the inside and outside of the hot box. In conclusion, a reliable U-value can be calculated for a temperature difference of $30^{\circ}C$ or more between the inside and outside of the hot box.

Skin Friction Mobilized on Pack Micropiles Subjected to Uplift Force (인발력을 받는 팩마이크로파일의 주면마찰력)

  • Hong, Won-Pyo;Cho, Sam-Deok;Choi, Chang-Ho;Lee, Choong-Min
    • Journal of the Korean Geotechnical Society
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    • v.28 no.6
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    • pp.19-29
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    • 2012
  • Pack micropiles were recently developed to improve pile capacity of general micropiles. Pack micropiles were made by warping thread bar or steel pipe of general micropile by geotexlile pack and grouting inside the pack with pressure. According to the pressure, the boring hole could be enlarged. A series of pile uplift tests were performed on three micropiles. Two out of the three piles were the pack micropiles and the other was the general micropile, in which a thread bar was used in the boring hole. According to the pressure applied to the pack micropiles, the diameter of boring hole was enlarged from 152 mm to 220 mm. Unit skin friction mobilized on side surfaces of micropiles increased with displacement of pile head and reached on a constant value, which represents that the relative displacement between piles (or thread bar) and soils was reached on critical state. And the uplift resistance of pack micropile was higher than that of general micropile. Two reasons can be considered: One is that the frictional surface increases due to enlarging diameter of boring holes and the other is that the unit skin friction could increase due to compressing effect of surrounding soils by soil displacement as much as the enlarging volume of boring hole. The compression effect appeared at deeper layer rather than surface layer. The unit skin friction mobilized on micropiles with small diameter was higher than the ones on large bored piles.

Study of Neonatal Cardiac Catheterization for Over the Last 10 Years (최근 10년간 신생아 심도자술의 변화)

  • Song, Jinyoung;Lee, Sungkyu;Lee, Jaeyoung;Kim, Sujin;Shim, Wooseup
    • Clinical and Experimental Pediatrics
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    • v.45 no.5
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    • pp.615-621
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    • 2002
  • Purpose : The neonatal cardiac catheterization and angiogram for transcatheter therapy are still essential methods in congenital heart disease, so we reviewed our experience with neonatal cardiac catheterization over 10 years at a single institution. Methods : A retrospective review of all 139 neonatal catheterizations from January 1991 to December 2000 at Sejong Heart Institution was performed. The purpose of the catheterizations, ages, body weights and the complications by the exam was surveyed. Results : The mean age of our 139 patients was 14.9 days and the mean body weight was 3.3 kg. As for the diagnosis : TGA in 49 patients, PAIVS in 26 patients, DORV in 14 patients, PS in 14 patients, PAVSD in 11 patients. For the cardiac catheterization, general anesthesia was performed in 65% of total and fluoroscopy time was $20.1{\pm}14.5$ minutes during cardiac catheterization. In the interventional cardiac catheterization which was 75% of the total, the age and body weight were statistically the same but the irradiation time was longer than the diagnostic catheterization( P=0.001). There were 48 cases of atrial septostomy, 16 cases of balloon pulmonary valvuloplasty and 25 cases of transcatheter pulmonary valvotomy. Complications of cardiac catheterization were found in 16.3%, but there was no difference between interventional catheterization and diagnostic catheterization. Conclusion : Therapeutic cardiac catheterization in neonates is a relatively safe and effective method in congenital heart disease.

A Case Study of RC Rahmen Structure Explosives Demolition (Focusing Demolition at Chungang Department in Daejeon City) (RC 라멘조 발파해체 적용사례와 기술.경제적 성과분석 -대전 중앙데파트 발파해체사례를 중심으로-)

  • Jung, Min-Su;Song, Young-Suk;Park, Yun-Seok;Heo, Eui-Haeng
    • Explosives and Blasting
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    • v.28 no.2
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    • pp.99-107
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    • 2010
  • Domestic explosive demolition techniques have been developed and applied for low-rise structures up to now. However, the demand for the development of those techniques that can be applied economically, safely and environment-friendly rapidly increases because the old high-rise RC rahmen structures that were built since around 1970s are now required to rebuild. As a result, element technologies of explosive demolition for low-rise structures were applied to take advantage of technology in high-rise structures that performed application testing at Chungang Department demolition field in Daejeon city. It could judge elements technology establishment for high-rise structure demolition and field application and suggest the improvements when the problems occurred to develop High-rise building demolition techniques for method of protection a field test and the dust reduction test. The water cannon test was applied to reduce the dust site and the drilling tests are performed to select the best components for explosives demolition elements techniques of the reliability. This paper shows that we have the ability to remove a high-rise building using environmentally friendly safe and economical explosives demolition method. It would contribute to prevent a foreign company from entering the domestic market and should contribute to acquire competitiveness of domestic demolition industry.

A study on the excavation cycle by the drill-and-blast method for a room-and-pillar underground structure (주방식 지하구조물의 발파 굴착공정 분석 연구)

  • Lee, Chul-Ho;Hyun, Young-Hwan;Hwang, Je-Don;Choi, Soon-Wook;Kang, Tae-Ho;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.6
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    • pp.511-524
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    • 2016
  • Since a room-and-pillar underground structure is characterized by its grid-type array of room and pillar, its economical efficiency can be governed by excavation sequence. In this study, the construction period by the drill-and-blast method as a excavation method for a room-and-pillar underground structure was examined. In addition, the parallel excavation sequence was considered as the main sequence of a room-and-pillar underground structure. Sequences of mucking and support installation were derived to estimate the total excavation cycle by taking the case of a road tunnel into consideration. From the excavation cycle of room-and-pillar underground structure, the relationship between available maximum and minimum numbers of jumbo drill machines depending on the number of faces in operation was suggested.