• Explosives and Blasting
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• v.22 no.3
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• pp.1-12
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• 2004

In bench blasting, rock fragmentation is one of the most important factors determining productivity. Rock fragmentation could be affected by various conditions and these were hewn that rock joint conditions and in-situ block sizes were the biggest effect on it. This research is focused on what or how to influence on rock fragmentation according to relation between blasting conditions and the in-situ rock conditions such as rock joint conditions and in-situ block size. Field measurements were carried out in 3 open pit limestone mines, where in-situ rock conditions and blasting conditions were fully investigated. The results show that the parameters interact with blasting conditions complicatedly and especially in-situ block size has bigger effects. Dip direction of major joint set also can affect on fragmentation. Mean fragment size become smallest when dip direction of major joint set is about $30^{\circ}$ with the bench direction. The reason is considered to be come from difference of propagation paths of elastic wave.

• Explosives and Blasting
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• v.34 no.3
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• pp.10-16
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• 2016

Recently, transition from open pit to underground mining in limestone mines is an increasing trend in Korea due to environmental issues such as noise, dust and vibrations caused by crushers and equipment. The severe damages in the surrounding rock mass of underground opening caused by explosive blasting may lead to rock fall hazards or casualties. It is well known that variables which mainly affect blast-induced rock falls in underground mining are: blast vibration level, joint orientation and distribution and shape of the cross sections of underground structures. In this study, UDEC program, which is a DEM code, is used to simulate blast vibration-induced rock fall in underground openings. Variation of joint space, joint angle and joint normal stiffness was considered to investigate the effect of joint characteristics on the blast vibration-induced rock fall in underground opening. Finally, jointed rock mass models considering blast-induced damage zone were examined to simulate the critical blast vibration value which may cause rock falls in underground opening.

• Cement
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• s.67
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• pp.25-41
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• 1977

미$\cdot$일에서 기 개발 운영되고 있는 대형 노천광산 및 광산장비 제작 공장에 대한 전반적인 실태 파악을 통하여 향후 대형화로 국제규모화될 당사 석회석 광산의 운영 및 기술적인 방향을 모색코자 함이 금번 출장의 목적이었다. 이에 당사 광산분야 기술자 6명으로 팀을 구성, 76년 하반기에 약 1개월은 미국에서, 약 1개월은 일본에서 양국 굴지의 10여 open pit mine 및 3개 장비 메이커를 방문 견학하였다. 금번 방문 결과 다음과 같은 점을 확인할 수 있었다. 첫째 금번 당사의 560만톤 증설은 사실상 미$\cdot$일을 앞지르고 국제적으로 굴지의 규모임을 확인할 수 있었고, 둘째 deposit(광상)의 지리적 여건비교에서는 미국의 것에는 뒤지나 일본의 조건에 비해서는 우리의 것이 결코 악조건이 아니며, 세째 특히 일본 석회석 광산업계가 안고 있는 제반문제점의 심각성(광구 경계 인접에 따른 분쟁, 시가지 인접에 따른 공해문제, 개발 여건의 불량 등)에 비추어 볼 때 국내 광산 기술자들의 노력 여하에 따라 일본은 충분한 경쟁대상이 될 수 있으며 국내시멘트업계 광산의 지리적, 지질적 여건상 일본광산보다 더욱 우수한 광산을 만들 수 있다는 자신감을 얻었다. 그러나 (1) long term 한 측면에서의 광산개발의 결여 (2) dyke와 폐토 처리 및 quarry QC의 불가피성 (3) 사회적 요소의 낙후(M.S 뇌관부재, 메이커 출장에 의한 장비의 수리, 화약류의 산원 혼합사용 등)등은 두드러진 우리의 결함이라고 느꼈으며 이들 결함의 시정, 보완을 위해서 사내외적으로 기존질서의 재검토가 이루어져야 할 것으로 사료된다. 미$\cdot$일 광산에서 일반화되어 있는 radio(walkie-talkie) system 및 electric shovel 주우 Cement Co., 산구사업소에서 시도된 belt 반전장치, 인력의 확대관리 등은 조기도입하여 실용화할수 있는 대상이라 생각하며 일철의 조형산 개발(72년 생산 개시, 광산 개발비 200억원, 연산 능력 800만톤)은 괄목할만한 것이었다. 또한 앞으로 국내업계 여건이 허락하는 한 광산 기술자의 해외파견 회수를 증가시켜 더 많은 사람들이 직접 보고 느끼어 우리의 것을 개선 창조해 나갈 수 있는 기회를 많이 가져 국내는 물론 국제 경쟁에 대처할 수 있는 업계 직원의 자질 향상을 바란다.

• Journal of Veterinary Clinics
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• v.34 no.2
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• pp.108-111
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• 2017

A 4-year-old, weighing 7.6 kg, castrated male, Pug presented with ingestion of gastric cavity foreign body. Physical examination revealed panting, retching and hyper-salivation. Blood chemistry and complete blood cell count were normal, but hypophosphatemia was observed. An abdominal radiograph revealed the foreign body (FB), round shape and 2 cm length, at the pyloric region of stomach. A thoracic radiograph revealed an incidental metal FB, 3.5 cm length, at the cranial portion of the diaphragm. An upper gastrointestinal endoscopy was performed to remove the FB in the stomach and then a peach-pit was removed. However the metal FB was not found in the esophagus therefore a lateral thoracotomy was performed. A right lateral thoracotomy through the $7^{th}$ intercostal space was accomplished to expose the right caudal lung lobe. After open the thoracic cavity, foreign body was not observed by gross evaluation and caudal lung lobe was attached to the diaphragm. The FB was identified inside the lung lobe and surrounded by granulation tissue. The metal FB (sewing needle) was removed with blunt dissection and incised lung lobe was sutured using absorbable suture material PDS 4-0 with interrupted suture. A thoracotomy tube was inserted into the thoracic cavity during surgery. Patient's respiration became stable after surgery. A chest tube was removed 3 days after surgery. No complications were noted and the dog was discharged 4 days after surgery. In small animal, foreign body ingestion is a common reason for emergency. After ingestion of the FB, perforation through the esophagus and migration to inside the lung lobe is not common in small animals. In this case, thoracic metal FB was identified incidentally and removal of a thoracic FB with thoracotomy was performed successfully.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.5
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• pp.742-747
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• 2019

Objective: A concentration of airborne bacteria generated from swine houses is recognized to be relatively higher than other work places and it is essential to optimally manage it to prevent farmers' respiratory diseases. This study was conducted to assess the distribution characteristics of airborne bacteria in swine houses located at South Korea. Methods: A total 27 pig buildings of the enclosed type operated with mechanical ventilation system by a side wall fan and deep-pit manure system with slats were surveyed. Air samples were collected at 1.0 m above the middle floor in pig housing room. A six-stage viable particulate cascade impactor was used to identify the distribution of the sizes of particles in diameter. Results: Seasonal mean levels of airborne bacteria in the housing rooms of gestation/farrowing pigs, nursery pigs and growing/fattening pigs were 3,428(${\pm}1,244$) colony forming unit $(cfu)/m^3$, $8,325({\pm}3,209)cfu/m$, and $13,254({\pm}6,108)cfu/m^3$ for spring; $9,824({\pm}2,157)cfu/m^3$, $18,254({\pm}5,166)cfu/m^3$, and $24,088({\pm}9,274)cfu/m^3$ for summer; $1,707({\pm}957)cfu/m^3$, $4,258({\pm}1,438)cfu/m^3$, and $8,254({\pm}2,416)cfu/m^3$ for autumn; and $2,322({\pm}1,352)cfu/m^3$, $6,124({\pm}1,527)cfu/m^3$ and $12,470({\pm}4,869)cfu/m^3$ for winter, respectively. Conclusion: Concentrations of airborne bacteria according to pig housing type were highest in growing/fattening housing room followed by nursery housing room and gestation/farrowing housing room. In terms of seasonal aspect, the pig building showed the highest levels of airborne bacteria in summer followed by spring, winter and autumn. The respirable airborne bacteria which are ranged between 0.6 and $4.7{\mu}m$ accounted for approximately 60% compared to total airborne bacteria regardless of pig housing type.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4253-4264
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• 2022

Since the implementation of the phosphate project in Bled El-Hadba (BEH) deposit, western region of Tébessa, no detailed study has been conducted to assess the natural radioactivity distribution and the associated radiological risk parameter for this open-pit mine. For the sake of determining a credible premining reference database for the region of interest, 21 samples were collected from different geological layers of the above-mentioned deposit. Gamma Spectrometry was applied for measuring radioactivity using a high resolution HPGe semiconductor detector. The obtained activity results have shown a significant broad variation in the radioactive contents for the different phosphate samples. The total average concentrations (in Bq·kg^-1) for ²²⁶Ra, ²³⁸U, ²³⁵U, ²³²Th and ⁴⁰K computed for the different type of phosphate layers were found to be 570 ± 169, 788 ± 280, 52 ± 18, 66 ± 6 and 81 ± 18 respectively. The mean activity concentrations of the measured radionuclides were compared to other regional and worldwide deposits. The ratios between the detected radioisotopes have been calculated for spatial distribution of natural radionuclides in the study area. Based on the aforementioned activity concentrations, the corresponding radiation hazard parameters were assessed. Correlations between the obtained parameters were drawn and a multivariate statistical analysis (Pearson Correlation, Cluster and Factor analysis) was carried out in order to identify the existing relationships.

• Journal of the Korean Applied Science and Technology
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• v.40 no.2
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• pp.332-341
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• 2023

The controversy is becoming a hot issue after informed that the water release from Canadian oil sands tailings may initiate within a few years. The surface-mined bitumen extraction in open pit generates wastewater inevitably, which has been conveyed to store in tailings ponds. Currently, the size of tailings pond is getting seriously larger. It is known that tailings treatment is very difficult because the generation of MFT (mature fine tailings) layer is hardly processable. It would be the key process to separate solids and liquid placed within MFT where fine particles are well dispersed. In this paper, the surface-mined bitumen extraction process was first introduced, and followed by presenting the components of tailings as well as the characteristics of MFT. In addition, MFT process options were evaluated. It is expected that successful MFT treatments may be achieved by dewatering process using effective polymer flocculants in near future.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.4
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• pp.419-425
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• 2009

Recently, the number of shallow tunnel construction increases to improve the structural safety and environment-friendliness. In Semi-Cut and Cover Method, ground is excavated to the crown arch level and braced rib arch is set to backfill before the excavation of lower face. Semi-Cut and Cover Method is proposed to solve the problems occurred by the conventional Cut and Cover Method, such as unstability, high-cost and the large cutting slope to be reinforced. In this paper, the behaviors of Braced Rib Arch in shallow tunnel excavated by semi-cut and cover method was studied. Model tests in 1:10 Scale were performed in real construction sequences. The distance between supports of rib arch was 1.8 m and the length of spacer was 1.0 m. the size of test pit was 4.0 m (width)$\times$3.3 m (length) 4.0 m (height) in dimension. Tests results show that backfill load acting on arch was smaller than that in the conventional Open-Cut Method.

• Journal of Animal Environmental Science
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• v.17 no.3
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• pp.155-162
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• 2011

This study was conducted to suggest the measurement procedure and to build up national greenhouse gas inventory database of animal agricultural sector by assessing methane and nitrous oxide emissions according to IPCC guidelines for national greenhouse gas inventory report in order to correspond to the Climate Change Convention. Ten house-made steady-state Half dome floating chambers were used to collect air samples emitted from slurry stored in the pit under the slat. Those chambers were spread out in order that air samples might represent the whole area of slurry under the slat. Fresh air was pumped into the chambers by $5{\sim}9{\ell}/min$ and air inside the chambers was sampled by $1{\ell}/min$. Surplus air by the higher flow rate of fresh air than sampling flow rate was passed through a hole on the top of chambers. Nitrous oxide fluxes measured from 10 locations would be negligible as concentrations between background air and sampled air from the chambers were within the error range. However, mean $CH_4$ fluxes were $0.15{\sim}1.02mg/m^2{\cdot}s$. The application of continuous greenhouse gas measurement techniques would be preferred if the patterns of greenhouse gas emissions are considered.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.488-496
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• 2010

Dens evaginatus is a tooth with cylindrical enamel projection which forms a nodule on occlusal surface. It could be explained as outward overgrowth of inner enamel epithelium or localized hyperplasia of pulpal mesenchymal tissue during tooth development. A problem is that it is likely to be worn out or fractured by mastication ensuing pulpal inflammation. It is occasionally found on the lingual surface of upper anterior teeth as well, called talon cusp. Dens invaginatus is a tooth with deep lingual pit made by invagination of lingual enamel epithelium during tooth development while it is considered normal in terms of size and shape. Radiographically, a part of cervical enamel shows inward growth forming cavity and it is reasonable to say that the base is possibly open to pulpal cavity since they are very close. Talon cusp and dens invaginatus are relatively common abnormality of shape. However it becomes the opposite if the two exist in the same tooth. Once the talon cusp is broken by occlusal force or fissure between cusps is decayed, the complicated structure of canals makes the pulpal treatment difficult. Preventive treatments such as occlusal equilibrium and sealant, and regular oral examination should be preceded and thorough understanding of canal shape, using radiography, is required when pulpal treatment is necessary. This report is about a 9- year-old boy(lower left central incisor), a 8-year-old girl(upper right central incisor), and a 7-year-old boy(upper right central incisor), who have dens invaginatus and talon cusp in the same teeth. The first and the second patients are under pulpal treatments, and the last one is being observed showing no pathologic impressions.