• Korean Chemical Engineering Research
• /
• v.57 no.3
• /
• pp.305-312
• /
• 2019

The discovery of nitric oxide (NO) as a major signaling molecule in a number of pathophysiological processes - vasodilation, immune response, platelet aggregation, wound repair, and cancer biology - has led to the development of various exogeneous NO delivery systems. However, the development of ideal delivery system for human body application is still left as a challenge due to its high reactivity and short half-life in physiological condition. In this article, an overview of several nano-structures as potential NO delivery system will be presented, along with their recent research results and biomedical applications. Nano-size delivery system has immense advantages compared to others due to its high surface-to-volume ratio and capability for surface modification; thus, it has been proven to be effective in delivering nitric oxide with enhanced performance. Through this novel nano-structure delivery system, we are expecting to achieve sustained release of nitric oxide within adequate range of concentration, which ensures desired drug effects at the target site. Among different nano-structures, in particular, nanoparticle, microemulsion and nanofilm will be reviewed and compared to each other in respect of nitric oxide release profile. The proposed nano-structures for exogeneous NO delivery have a biological significance in that it can be further utilized in diverse biomedical fields as a highly promising therapeutic method.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.30 no.6
• /
• pp.244-250
• /
• 2020

β-Tricalcium phosphate (β-TCP, Ca3(PO4)2) is a kind of biodegradable calcium phosphate ceramics with chemical and mineral compositions similar to those of bone. It is a potential candidate for bone repair surgery. To improve the bioactivity and osteoinductivity of β-TCP, various ions doped calcium phosphate have been studied. Among them, Iron is a trace element and its deficiency in the human body causes various problems. In this study, we investigated the effect of Fe ions on the structural variation, degradation behavior of β-TCP. Fe-doped β-TCP powders were synthesized by the coprecipitation method, and the heat treatment temperature was set at 925 and 1100℃. The structural analysis was carried out by Rietveld refinement using the X-ray diffraction results. Fe ions existed in a different state (Fe2+ or Fe3+) with different heat treatment temperatures, and the substitution sites (Ca-(4) and Ca-(5)) also changed with temperature. The degradation rate was fastest at Fe-doped β-TCP with heated at 1100℃. The cell viability behavior was also enhanced with the substitution of Fe ions. Therefore, the substitution of Fe ion has accelerated the degradation of β-TCP and improved the biocompatibility. It could be more utilized in biomedical devices.

• Conservation Science in Museum
• /
• v.25
• /
• pp.51-62
• /
• 2021

The Belt with Rhinoceros-Horn Ornaments(known as a seodae in Korean) from the family of Princess Deokon's descendants housed in the National Hangeul Museum underwent emergency treatment for a special exhibition in 2019 upon the request of the National Hangeul Museum. Priority was given to the restoration of the original form of the severely damaged belt and the repair of its detached horn ornaments. Prior to the conservation treatment, researchers conducted a theoretical study of the belt with rhinoceros-horn adornments to learn the names of its structural components and the changes in form that the type experienced by period, thereby establishing a plan for conservation treatment and setting a direction. Among the belts worn by officials from the Joseon dynasty, rhinoceros-horn ornaments were attached to those of officials of the first rank and were considered the most precious behind the king's belt with its jade ornaments. The rhinoceros horn adorning the belt is classified into three categories according to quality. This belt has horn adornments of the highest quality, falling under the "grape design" category with dark brown dots concentrated in the center. The belt has a rectangular shape and lacks a buckle, reflecting a popular form from the nineteenth century. The structure of the belt was identified over the process of conservation treatment, offering information about its method of production. In addition, comparison of the relic with belts with rhinoceros-horn ornaments depicted in Joseon-period portraits of officials allowed the identification of changes in formal features and the detailed structures of belts with rhinoceros-horn ornaments by period. It confirmed that the belt subject to conservation treatment shows the features of belts with rhinoceros-horn ornaments produced in the nineteenth and twentieth centuries.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.385-392
• /
• 2021

In general, earth retaining work in construction works enables the construction of structures, prevents the displacement of the surrounding ground to the maximum extent, and plays an important role in ensuring the safety of the surrounding structures and field workers. The earth retaining work and the construction method differ according to the various ground characteristics, surrounding topographical characteristics, repair environment, and design conditions. In particular, in the case of Seoul city, the environments and ground conditions differ according to the area. This study analyzed the earth retaining work cost mainly for the apartment construction project in Seoul and calculated the approximate earth retaining work cost at the project planning stage. A model was developed to predict the cost of earth retaining work that matches the characteristics of Seoul City and predict the construction cost for earth retaining work. This paper presents the predicted earth retaining work cost using a multiple regression model that applies 10 project outlines as independent variables. The error rate of the prediction result of the earth retaining work cost of the apartment construction project in Seoul using multiple regression models was 10.75%.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.15 no.4
• /
• pp.283-290
• /
• 2022

In this study, an IoT inspection system that can be linked with a server was developed using a gas timer and ESP-01 Wi-Fi module installed on a gas valve in the home. The server environment of the gas leak IoT inspection system was installed with APM (Apache, PHP, MySQL) to collect gas pressure data by generation so that leakage checks could be performed. In order to control the gas leak IoT inspection system, the app inventory was used to manage the gas leak check value in real time. In addition, user convenience has been enhanced so that membership management, WiFi settings, and leakage check values can be checked through mobile apps. In order to manage subscribers by region, the user list was checked by logging in in in the administrator mode so that the information on whether or not the leak test was conducted and the results could be provided. In addition, when the user presses the gas leak check button, the pressure is automatically checked, and the measured value is stored in the server, and when a gas leak occurs, the leakage check is performed after alarm and repair so that it can be used if normal. In addition, in order to prevent overlapping membership, membership management can be performed based on MAC addresses.

• The Journal of the Korea Contents Association
• /
• v.22 no.2
• /
• pp.147-161
• /
• 2022

This study examined changes in the ecological characteristics and design characteristics of Ban's exhibition space in three representative temporary exhibition halls and three permanent exhibition halls designed by Ban Shigeru since 2000. Through the investigation of the concepts and characteristics of ecological architecture, the design characteristics of exhibition space, the analysis framework of the design characteristics of exhibition space and the design elements of ecological architecture is obtained. The analysis results show that there are big changes between the temporary exhibition space and the permanent exhibition space in terms of building scale, space composition, function, materials and technology. On the one hand, the temporary exhibition space used recyclable materials, such as paper tubes, containers to be assembled on site into a single-layer space focused on display. The assembly method was simple and the construction period was short. After the exhibition, the exhibition space were dismantled. The materials were either transported to the next display site or recycled and reused. On the other hand, the permanent exhibition space used reinforced concrete as the main structure, and used a large amount of wood and glass materials to construct a multi-layered composite cultural space that separated the exhibition space and the leisure space. In terms of ecological characteristics, the building materials of the temporary exhibition space were recycled and no industrial wastes were generated after the demolition. The permanent exhibition hall uses eco-friendly wood for the roof and walls, so it is easy to replace and repair. Both types of exhibition halls are changing ecological architecture in a more sustainable direction by saving resources and energy through natural light and ventilation.

• Journal of the Korean Institute of Gas
• /
• v.27 no.2
• /
• pp.1-6
• /
• 2023

PE piping, which has advantages in terms of construction convenience and economy, is widely used for underground burial in the domestic urban gas field. These PE pipes use squeeze-off in many sites to block gas flow during maintenance and repair work. Squeeze-off refers to a method of compressing a PE pipe to block fluid flow, and damage may occur due to the nature of construction in which the pipe is deformed by physical force. In order to prevent damage to PE pipes due to squeeze-off, the main points to be reflected in the squeeze-off operation procedures such as proper compression range, use pressure, and diameter were derived through damage assessment and confidential test according to the compression rate. The compression experiment for PE pipe damage assessment was conducted while changing the compression rate (20%~40%), the pressure of use (2.8 kPa, 25 kPa, 70 kPa), and the pipe diameters (63 mm, 90 mm, 110 mm). As a result of damage assessment according to the compression rate, damage occurred in pipes with compression rates of 45%(110mm) and 73%(63mm), which are for analyzing the effect of excessive compression. In addition, the leakage test was conducted using Ar(argon) during the squeeze-off, and as a result of the experiment, leakage occurred under the conditions of 70kPa and 110mm of pipe. As a result of this study, it was confirmed that squeeze-off for airtightness should be carried out in pipes within a range not exceeding 25 kPa and 90 mm pipes, and the appropriate compression rate to prevent damage to PE pipes is 30%.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.7
• /
• pp.980-991
• /
• 2023

To prevent accidents near the quay caused by a ship, ports are generally designed and constructed through navigation and berthing safety assessment. However, unpredictable accidents such as ship collisions with the quay or personal accidents caused by ropes still occur sometimes during the ship berthing or mooring process. Automatic mooring systems, which are equipped with an attachment mechanism composed of robotic manipulators and vacuum pads, are designed for rapid and safe mooring of ships. This paper deals with a displacement and velocity measurement system for the automatic mooring device, which is essential for the position and speed control of the vacuum pads. To design a suitable system for an automatic mooring device, we first analyze the sensor's performance and outdoor environmental characteristics. Based on the analysis results, we describe the configuration and design methods of a displacement and velocity measurement system for application in outdoor environments. Additionally, several algorithms for detecting the sensor's state and estimating a ship's velocity are developed. The proposed method is verified through some experiments for displacement and speed measurement targeted at a moving object with constant speed.

• The Korean Journal of Air & Space Law and Policy
• /
• v.31 no.2
• /
• pp.37-72
• /
• 2016

In the aerospace field, besides special purpose airplanes, contracts for supply of various types of products such as prototypes, unmanned aerial vehicles and space launch vehicles are increasing. In the case of the contractor, it was planned to spend a large amount of money to supply the production, but if the purchase specification that presents the quality and performance standard of the product is poor or lacks the capacity to judge the performance, consuming enormous amounts of time and money. Even if the undertaker does not have the ability to supply the products with the required performance and quality to achieve the purpose of the contract, he/she must pay the cost of burial due to the incompleteness of the work and the compensation for the cancellation of the contract. In this case, the defendant ordered the plaintiff to supply the aircraft by the Happy Box method, which is capable of ILS Offset flight as specified in the Purchase Specification, but the plaintiff attempted to supply the aircraft by the RNAV method. Although the ILS ground signal can be inspected by the RNAV method, the aircraft manufactured in the manner claimed by the plaintiff does not have the ILS Offset flight function required by the purchase specification, so the defendant can not achieve the purpose required by the purchase specification. It was a question of whether a defendant's cancellation of contract was legitimate. The aircraft, which is the object of this contract, is a subordinate substitute, so the case contract is of undertaking. Therefore, in order to complete the work in this contract, the major structural parts of the aircraft must be manufactured as agreed and have the performance generally required in the social sense. However, the aircraft delivered by the plaintiff has serious defects because the defendant can not achieve the purpose required by the purchase specification due to the lack of the ILS Offset flight function required by the purchase specification. This deficiency is impossible for the plaintiff to repair, so the defendant 's cancellation of the contract is legitimate.

• Journal of Chest Surgery
• /
• v.38 no.8 s.253
• /
• pp.538-544
• /
• 2005

Background: Pulmonary artery banding (PAB) is an initial palliative procedure for a diverse group of patients with congenital cardiac anomalies and unrestricted pulmonary blood flow. We proved the usefulness of PAB through retrospective investigation of the surgical indication and risk analysis retrospectively. Material and Method: One hundred and fifty four consecutive patients (99 males and 55 females) who underwent PAB between January 1986 and December 2003 were included. We analysed the risk factors for early mortality and actuarial survival rate. Mean age was $2.5\pm12.8\;(0.2\sim92.7)$ months and mean weight was $4.5\pm2.7\;(0.9\sim18.0)\;kg$. Preoperative diagnosis included functional single ventricle $(88,\;57.1\%)$, double outlet right ventricle $(22,\;14.2\%)$, transposition of the great arteries $(26,\;16.8\%)$, and atrioventricular septal defect $(11,\;7.1\%)$. Coarctation of the aorta or interrupted aortic arch $(32,\;20.7\%)$, subaortic stenosis $(13,\;8.4\%)$ and total anomalous pulmonary venous connection $(13,\;8.4\%)$ were associated. Result: The overall early mortality was $22.1\%\;(34\;of\;154)$, The recent series from 1996 include patients with lower age $(3.8\pm15.9\;vs.\;1.5\pm12.7,\;p=0.04)$ and lower body weight $(4.8\pm3.1\;vs.\;4.0\pm2.7,\;p=0.02)$. The early mortality was lower in the recent group $(17.5\%;\;16/75)$ than the earlier group $(28.5\%;\;18/45)$. Aortic arch anomaly (p=0.004), subaortic stenosis (p=0.004), operation for subaortic stenosis (p=0.007), and cardiopulmonary bypass (p=0.007) were proven to be risk factors for early death in univariate analysis, while time of surgery (<1996) (p=0.026) was the only significant risk factor in multivariate analysis. The mean time interval from PAB to the second-stage operation was $12.8\pm10.9$ months. Among 96 patients who survived PAB, 40 patients completed Fontan operation, 21 patients underwent bidirectional cavopulmonary shunt, and 35 patients underwent biventricular repair including 25 arterial switch operations. Median follow-up was $40.1\pm48.9$ months. Overall survival rates at 1 year, 5 years and 10 years were $81.2\%\;65.0\%,\;and\;63.5\%$ respectively. Conclusion: Although it improved in recent series, early mortality was still high despite the advances in perioperative management. As for conventional indications, early primary repair may be more beneficial. However, PA banding still has a role in the initial palliative step in selective groups.