• Journal of the Korean Professional Engineers Association
• /
• v.15 no.4
• /
• pp.12-24
• /
• 1982

East Parts of Bangladesh have been benifited by low cost energy generated by domestic natural gas but West parts where energy generated by imported fuel. Bangladesh Government authority has very much concerned to transmit the low cost electricity to the West from the East for past several years. To solve such concerns, cross-country 230kv double circuits Power transmission line was proposed, however there was a big obstacle for the realization of this line to cross the Jamuna river which has 12 km long width with a deep muddy river bed. A consultant engineering firm named Merz-Mclellan anyway finalized this plan and a world-wide bid was announced on June 31, 1979. Due to the expected difficulty to construct the towers on sea like area, only three construction groups have participated. including a Korean joint venture organization of Samsung-Korean Developement corporation-Kolon Electric Machinery company. After 3 months bid evaluation, contract was awarded to Korean Consosium and KEM Co was in charge of designing steel towers with anchor bolts and base plates beside to electrical engineering field. Then KEM Co have faced and over-comed many unenpected technical difficulties such as forced eccentricity joint on base plate, distorsion issue of 60mm thick plates welding, threading anchor bolts, tad heat treatment of some anchor bolts, disagreement from Consultant Engineer on multiplying factor of leg stresses for 45$^{\circ}$ wind and on reducing O.L.F for wind loads on cables for such 1220km long spans. After spending two years long period for designing and engineering towers, base plates, and anchor bolts, first shipment of tower was finally realized on Nov. 8, 1981 and on the other hand KDD has proceeded concrete caisson work on schedule at Jamuna river site and expected to complete tower erection and stringing of cables within this year of 1982 which was original completion target.

• Korean Journal of Veterinary Research
• /
• v.36 no.3
• /
• pp.599-605
• /
• 1996

This study was designed to examine the mechanism of penile erection in adult bull by analyzing the responses of bovine proximal retractor penile muscle strips(BRP) to electtical field stimulation(EFS), exogenous nitric oxide(NO), NO synthesis precursor(L-arginine), NO synthase inhibitors(L-NAME, L-NMMA), guanylate cyclase inhibitor(methylene blue) and nonspecific potassium channel blocker(tetraethylammonium, TEA) treatments. Isometric tension of BRP was measured using physiograph. Results were summarized as follows: 1. EFS of nonadrenergic noncholinrgic(NANC) nerve in BRP produced frequency-dependent inhibitory responses to the contraction induced by co-treatment of epinephrine, guanethidine and atropine. The inhibitory responses to EFS were blocked by tetrodotoxin(TTX, $1{\mu}M$). 2. Treatment of L-NAME ($10,\;20{\mu}M$) inhibited the relaxation to EFS whereas L-NMMA ($100{\mu}M$) had no effect. 3. Treatment of NO($20,\;40{\mu}M$; as an acidified solution of $NaNO_2$) induced concentration-dependent relaxation whereas preincubation of TTX($1{\mu}M$) and L-NAME($20{\mu}M$) had no effect on the relaxation response. 4. L-arginine treatment(10mM) blocked the inhibitory effect of L-NAME($20{\mu}M$). 5. Pretreatment of methylene blue($40{\mu}M$) reduced the NANC-induced relaxation of BRP. 6. Tetraethylammonium(TEA, 80mM) reduced NANC relaxation. These results suggest that NO may act as a NANC neurotransmitter in BRP and the effects might be mediated by cGMP and potassium channel.

• Computational Structural Engineering
• /
• v.10 no.2
• /
• pp.189-201
• /
• 1997

A number of standard type of steel-box pedestrian bridges are constructed in th metropolitan high way or heavy traffic urban area. Although it has the advantage of speedy construction because of its simple structural form and prefabricated erection method, it has been reported that many of these bridges are deteriorated or damaged and thus are in the state such that it would give unsafe and uncomfortable feeling to pedestrians. In the paper, for the realistic assessment of safety and load carrying capacity of deteriorated and/or damaged steel box pedestrian bridges, an interactive non-linear limit state model is formulated based on the von Mises' combined stress yield criterion. It has been demonstrated that the proposed model is effective for the reliability-based safety assessment and load carrying capacity evaluation of steel-box pedestrian bridges. In addition, this study suggests an effective and practical field load test method for pedestrian bridges.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.6
• /
• pp.863-873
• /
• 2023

This research explores the efficacy of safety vest colors at construction sites to enhance worker safety. Utilizing the Munsell color system and the Korean Standard Color Analysis program(KSCA), the study developed a prototype safety vest tailored to specific types of construction work. A safety vest with a color contrasting the site's environment significantly improves worker visibility and intuitiveness in identification, potentially reducing safety incidents. The study determined the optimal color specifications(hue, value, chroma) for safety vests in various construction roles, such as 10GY, 8, 8 for rebar placement, 8.75B, 7, 8 for Euroform, 3.75B, 2, 4 for Gangform, and 6.25BG, 5, 10 for steel erection. Feedback from construction experts on these prototypes, particularly regarding the safety vests for rebar placement and steel framework, was overwhelmingly positive(90% approval). Consequently, the proposed safety vest color scheme is deemed highly effective.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.3
• /
• pp.261-273
• /
• 2011

Recently, the demands for steel frame are increasing because of the trend and due to the demand for bigger and higher buildings. In the analysis of typical steel frame, connections are based on the idealized fixed or pinned connection. A fixed connection assumes that the relative angle of each member before deformation is the same after the transformation. Therefore, the stiffener reinforces the connection to sufficient rigidity and stability of the panel zone. In the economical aspect, however, the necessity of connection that the stiffener reinforcement has omitted is increasing due to the excessive production as well as labor costs of connection. In contrast, pinned connection is assumed that bending moments between the beams and columns do not transfer to each member. This is easy to make in the plant and the construction is simple. However, the structural efficiency is reduced in pinned connection because connection cannot transfer moments. The introduction of this semirigid process can decide efficient cross-sectional dimensions that promote ease in the course of structural erection, as performed by members in the field-a call for safety in the entire frame. Therefore, foreign countries exert efforts to study the practical behavior and the results are applied to criterion. This paper analyzes the semirigid connection of domestic steel by design specifications of AISC/LRFD and make data bank that pertain to each steel. After wards, the results are compared to those of idealized connection; at the same time, this paper presents a design method that matches economic efficiency, end-fixity, and rotational stiffness.

• Journal of Korean Association for Spatial Structures
• /
• v.11 no.2
• /
• pp.129-138
• /
• 2011

Construction methods for underground structure are classified as bottom-up, up-up, and top-down methods depending on the procedure of construction related to a superstructure. In top-down construction methods, building's main structure is built from the ground level downwards by sequentially alternating ground excavation and structure construction. In the mean time, the main structure is also used as supporting structure for earth-retaining wall, which results in the increased stability of the earth-retaining wall due to the minimized deformation in adjacent structures and surrounding grounds. In addition, the method makes it easy to secure a field for construction work in the downtown area by using each floor slabs as working spaces. However top-down construction method is often avoided since an excavation under the slab has low efficiency and difficult environment for work, and high cost compared with earth anchor method. This paper proposes a combined construction method where semi-open cut is selected as excavation work, slurry as earth -retaining wall and CWS as top-down construction method. In the case study targeted for an actual construction project, the proposed method is compared with existing top-down construction method in terms of economic feasibility, construction period and work efficiency. The proposed construction method results in increased work efficiency in the transportation of earth and sand, and steel frame erection, better quality management in PHD construction, and reduced construction period.

• Korean Journal of Heritage: History & Science
• /
• v.41 no.1
• /
• pp.109-125
• /
• 2008

Recently, there has been an increase in excavation studies of wood pagodas from the Three Kingdoms and Unified Shilla periods and new data related to wood pagoda erection are being found bringing about progress in research on this field. In other words, studies on wooden pagodas in Korea were composed mainly of flat, axis construction techniques and sarijangeomgu, but by acquiring new data, it has now become possible to study not only the stylobate construction procedure and transition, but also studies on restoring wooden pagodas. Furthermore, pagoda sites similar to this were found in China and Japan as well, making it possible to make comparative studies among ancient wooden pagodas possible. In this paper, the main remains were set as Baekjae wooden pagodas, which were the most frequently studied and among the wooden pagodas, the simcho (central base stone) and sarira housing locations. In result, simcho can be found changing its position from underground ${\rightarrow}$ halfway underground ${\rightarrow}$ above ground. Baekjae wooden pagodas up until the mid sixth century located at Neungsan-ri saji (AD 567) and Wangheungsaji (AD 577) had its simcho located underground and later it was constructed halfway underground and then above ground. It was confirmed that in the 7th century, it became customary to place above ground as seen in the Jaeseoksaji (AD639) and Hwangnyongsaji (AD645) wooden pagoda sites. The sarira was usually located on the south side of the simcho, but gradually changed to the center. In particular, sarira were combined in the simcho in the mid sixth century at the Wangheungsaji. This is approximately 11 years earlier than the Bijosa (AD 588) simcho found in Japan and this was not found even in the simcho of wooden pagodas in Yeongnyeongsa (AD 516) and Jopaengseong temple (AD 535~561) of China showing that the Wangheungsaji simcho was the earliest of its kind.