• Archives of design research
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• v.19 no.5 s.67
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• pp.351-362
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• 2006

Currently, finding one's way in the underground spaces associated with subway stations in large cities is becoming a serious problem, and an environment that facilitates wayfinding is becoming more important. This study investigated interior treatments that function as visual cues in the subway stations of Seoul, Tokyo, and Taipei in order to develop design guidelines that would improve the place-cognition environment. A theoretical study has shown that there are three categories of visual cue for place cognition: marked trails, regional differentiation, and landmarks. The case study showed that marked trails involve treatments like vertical markers, confrontational positioning, and subway color codes. Regional differentiation involves patterns on the floors and walls, and accent colors on the walls and columns. Landmarks include treatments such as super graphics, symbolic features, artistic decoration and special lights. In the cases of Seoul, marked trails and regional differentiation were predominant. In addition, the Olympic symbol 'Hodori' and the ancient Korean character "Hunminjungeum" were used as landmarks. In the cases of Tokyo, regional differentiation predominated over marked trails because of the complexity of the spatial structure and subway line connection system. In the cases of Taipei, simple, unified images predominated, and there was minimal dependence on marked trails and landmarks. The need for regional differentiation was weak, because the stations studied have open structures that guarantee an open field of view. The results of this research could be used as design guidelines, after further experimental verification, that would help to improve the public environment in terms of wayfinding.

• Tunnel and Underground Space
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• v.25 no.1
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• pp.107-114
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• 2015

This study focuses on assessing risks which might occur in operation stage of CAES storage cavern and analyzing fire scenarios for the risk that have been assessed with highest risk level. Risks in operation stage were categorized into upper risk group and lower risk group. Components of upper risk group are technical risk, facility risk and natural disaster risk. Lower risk group is composed of 11 sub-risks. 20 experts were chosen to survey questionnaires. ANP model was applied to analyze the relative importance of 11 sub-risks. Results of risk analysis were compared with risk criterion to set risk priorities, and the highest risk was determined to be 'occurrence of the fire within the management opening'. Three fire scenarios were developed for the highest risk level and FDS (Fire dynamics Simulator) was used to analyze these scenarios. No. 3 scenario which air blows from tunnel into outside atmosphere represented that a rate of smoke spread was the fastest among three fire scenarios and a smoke descended most quickly below the limit line of breathing. Thus, No. 3 scenario turned out to be the most unfavorable condition when operating staffs were evacuated from access tunnel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.809-819
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• 2004

In this paper, in order to exclude the expansion of M/W relay frequency or its new frequency assignment possibly, we analyzed a possibility of substituting M/W system by B-WLL or optical fiber network regarding service quality and economical points. To define the target of service quality, pre-condition and analysis method for the selected media have been derived to compare each other. E1 transmission with BER 10$^{-1}$ was chosen as a reference capacity, and service distance was calculated f3r the selected media as a function of availability. Also from the economical point we considered 3 systems such as optical fiber, M/W, and B-WLL based upon basic system structure, and analyzed them for various line configurations of fiber optic and B-WLL according to service period, system capacity, transmission distance, and data rate. It was confirmed that B-WLL can provide quality of service with 99.999 % availability within 1.6 km cell radius, and for optical fiber substitution, the leased fiber conduit on an electric pole is more economical than M/W system irrespective of service period, but in case of directly digging for underground conduit, it turned out ineffective regardless of cabling duct types.

• Tunnel and Underground Space
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• v.24 no.4
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• pp.297-307
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• 2014

Cavern Thermal Energy Storage system stores thermal energy in caverns to recover industrial waste heat or avoid the sporadic characteristics of renewable-energy resources, and its advantages include high injection-and-extraction powers and the flexibility in selecting a storage medium. In the present study, the structural stability of rock mass pillar between these silo-type storage caverns was assessed using a coupled thermal-mechanical model in $FLAC^{3D}$. The results of numerical simulations showed that thermal stresses due to long-term storage depended on pillar width and had significant effect on the pillar stability. A sensitivity analysis of main factors indicated that the influence on the pillar stability increased in the order cavern depth < pillar width < in situ condition. It was suggested that two identical caverns should be separated by at least one diameter of the cavern and small-diameter shaft neighboring the cavern should be separated by more than half of the cavern diameter. Meanwhile, when the line of centers of two caverns was parallel to the direction of maximum horizontal principal stress, the shielding effect of the caverns could minimize an adverse effect caused by a large horizontal stress.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.357-367
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• 2006

Recently, as the construction of new railway and the relocation of existing line increase, tunnel structures grow longer. The railway fire accidents in long tunnel bring large damages of human life and disaster. The interest of safety in long tunnel have a growing and the safety standard of long tunnel is tightening. For that reason, at the planning of long tunnel, the optimum design of safety facility in long tunnel for minimizing the risks and satisfying the safety standard is needed. For the reasonable design of long railway tunnel considering high safety, qualitative estimation for tunnel safety is required. In this study, QRA (Quantitative Risk Assessment) technique is applied to design of long railway tunnel for assuring the safety function and estimating the risk of safety. The case study for safety design in long railway tunnel is tarried out to verifying the QRA technique for two railway tunnels. Thus, the inclined and vertical shaft for escape way and safety facilities in long tunnel are planned, and the risks of tunnel safety for each case are estimated quantitatively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.20-27
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• 2014

In the construction site, various earth retaining systems are developed and applied to maintain stability of excavated area and structures. Among the methods, the underground continuous wall and the column-type diaphragm wall methods are especially used in construction site nearby buildings or roads. However, these methods have some disadvantages such as the difficulty of quality control and long curing time because these methods need to cast fresh concrete at the construction site. In addition, these methods are usually applied to the site for the temporary purpose. In this paper, we suggest precast hollow prestressed concrete pile for continuous pile wall system. To investigate the structural behavior of suggested pile, which is the main member of the suggested system, tests pertaining to the structural behavior and prestressing force applied in the pile are conducted. From the test results, it was found that the prestressing force measured is sufficient compared with the value obtained by the design equation and the cracking moment measured is 34% higher than the design value. In addition to the above, this precast hollow prestressed concrete pile has an additional safety margin that the maximum moment is 59.2% higher than the cracking moment which is one of the serviceability limits for the design of the system.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.04b
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• pp.29-30
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• 2001

자연에너지원중 태양에너지를 이용한 자갈축열 태양열 온실의 난방에너지 절감효과를 분석하기 위하여 야간에 내부설정온도를 18℃로 했을 때의 자갈축열 태양열 온실과 동일한 제원의 대조온실의 난방연료소비량을 비교하였다. 자갈축열 태양열 온실의 경우 난방초기에는 연료가 대조온실에 비해 약 10%정도 더 소모되었으나 2일이 경과한 후에는 점차 난방연료소비량이 감소하였다(Fig. 2) 이러한 결과는 자갈축열 태양열 온실의 경우 주간에 온실에 투여되는 일사에 의해 축열이 이루어 질뿐만 아니라 야간에 난방을 할 경우에도 축열층의 온도가 설정온도에 도달할 때까지 축열이 이루지기 때문인 것으로 분석되었다 (Fig. 1). 3월 10일부터 3월 15일까지 6일간의 난방연료소비량이 대조온실은 167℃였으나, 자갈축열 태양열 온실은 109℃로써 대조온실에 비해 약 35%정도 난방연료 절감효과가 있는 것으로 분석되었다(Fig. 2). 6일간의 난방 후 자갈축열 태양열 온실에 난방을 중단한 결과 온실외부의 최저기온이 -2.4℃일 때 자갈축열 태양열 온실의 내부최저온도는 14℃를 유지하였으며, 이후 계속 난방을 수행하지 않은 상태에서도 주간에 축열효과로 인하여 최저외기온이 3℃전후일 때 자갈축열 태양열 온실의 내부온도는 15℃를 유지하였으나 대조온실은 5℃ 전후였다. 그리고, 일기온차가 심한 3월말에는 야간설정온도가 18℃인 경우에 자갈축열 태양열 온실의 난방연료소비량이 대조온실에 비해 월등히 적음을 알 수 있었다(Fig. 1, 2). 3월에 자갈축열 태양열 온실의 난방연료소비량은 대조온실에 비해 약 50%이상의 절감효과가 있는 것으로 나타났다./TEX>3.1cm, 2cm$\times$4.2cm 순으로 나타났다. 5. 저고리의 옆길이 곡선에 대한 평가는 진종의 중심인 겨드랑이가 5cm인 것이 가장 우수한 것으로 나타났으며, 그 다음으로 4cm, 6cm, 3cm 순으로 나타났다. 6. 이에 위의 항목들을 종합하여 제작한 연구저고리는 등길이가 28cm, 어깨선 위치는 1.75cm, 깃크기는 5cm$\times$21.5cm, 소매통 크기는 3cm$\times$4.3cm, 옆길이 곡선은 5cm로써 그 형태에 따른 신체적합성에 대한 외관 관능검사 결과로 3.83의 평균값으로 나타났고, 심미성에 대한 외관 관능검사를 항목별 평균치 값으로 종합하면 4.00의 값으로 나타났다. 또한 각 부위별 동작적합성 관능검사는 7가지 동작을 부위별 항목 평균치 결과 3.95의 유수한 저고리로 평가되었다. 본 연구 실험 결과 앞으로도 전통 저고리를 피복함에 있어 외관과 동작적합성이 좋은 저고리를 만들기 위해 지속적 연구가 요청된다. turned back than the Korean women's. Based on the above findings, a torso prototype was developed for the Chinese women by setting the body measurements in reference with their average body measurements plus minimum reserve. The reference lines were set for front/back central line, front/

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.209-216
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• 1999

In order to get geologic information necessary for underground installation of water pipe, seismic refraction profiling was applied to the southwest side of the Seomjin River which flows between Namwon-gun, Cholabuk-do and Gokseong-gun, Cholanam-do. Before obtaining the in-line refraction data, walkaway data were recorded with 1 m geophone interval and -36∼+36 m offset range. From the walkaway data, it is interpreted that a dry soil layer with the average velocity of 585 m/s covers wet sediments with the average velocity of 1,326 m/s. The second layer overlies basements nearly horizontally with the average velocity of 4,218 m/s. Refraction profiling of 220 m long with the geophone interval of 2 m is interpreted with the Generalized Reciprocal Method (GRM). Three layers are identified with average velocities of 688 m/s, 1,473 m/s, and 3,776 m/s, respectively. The depth to the bedrock impossible for ripping ranges between two extremes, 1.51∼2.43 m and 2.25∼3.54 m, depending upon thickness of the hidden layer. A typical shortcoming of refraction method, the hidden layer problem, prevents accurate estimation in depth of the second layer.

• Tunnel and Underground Space
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• v.15 no.3 s.56
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• pp.223-227
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• 2005

The physical and mechanical properties of volcanic glass, which is distributed in the Samho area, South Korea were studied. Laboratory rock tests were carried out in order to obtain the various properties of rocks. Specific gravity, water content, absorption, porosity and wave velocity were measured for the physical properties. Uniaxial and triaxial compressive tests, Brazilian test and point load test were also performed for the mechanical properties. The tests of volcanic glass revealed that the apparent specific gravity, water content and absorption were 2.28, $1.67\%$ and $1.72\%$, respectively. Porosity $(3.87\%)$ was lower, whereas P-wave velocity (5330m/s) and S-wave velocity (2980 m/s) were relatively higher. Brazilian tensile strength ot 7.2MPa, and point load strength of 2.6MPa were among the mechanical properties of the rock. Uniaxial compressive strength (62.4MPa) estimated ken point load strength was very closed to the value (66.0MPa) from the uniaxial compressive test. Young's modulus and Poisson's ratio were E=43.2 GPa and v=0.28, respectively. Drawing the tangent line to Mohr-Coulomb failure criterion showed the cohesion of 20.1MPa and internal fraction angle of $28.6^{\circ}$.

• Explosives and Blasting
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• v.39 no.3
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• pp.15-23
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• 2021

Ventilation shafts are pathways in mines and tunnels for the removal of dust or smoke during underground space construction and operation. In mines, blasting with long blast holes is preferred for the excavation of a ventilation shaft in the 10~20m long crown pillar section. In this case, the bottom part of the blast hole is completely drilled in order to determine the drilling error, and this causes a problem of lowering the explosive charge and blasting efficiency. It is possible to solve the problem of explosive loading and to increase the blast efficiency by covering the curb of the blasthole by using stemming material. In this study, simulations for the blasting of a ventilation shaft were performed with various stemming lengths and the blasthole diameters(45, 76mm) using AUTODYN 2D SPH(Smooth particle hydrodynamics) analysis technique. Also the optimal bottom stemming column was derived by checking the size of the boulder and burden line according to blasting. Analysis result, blasting efficiency is lessened in case of stemming length less than 30cm and the optimal length of the stemming material should be 30cm or higher to achieve high efficiency of blasting.