The purpose of this study is to develop an electroless nickel plating process suitable for IXEF 1022, which is a high-performance polymer, and to analyze the effect of plating temperature on plating quality in particular. The experiment was conducted at 80°C, 83°C, and 85°C, and as a result, it was confirmed that as the temperature increased, the thickness and external dimensions of the plating layer gradually increased, and the plating layer tended to be uniformly formed on the entire surface. In addition, the adhesion and quality of the plating layer were maintained stably even at high temperatures, which proves the practicality and reliability of the process. These results contribute to the improvement of the conductivity and durability of IXEF 1022, and suggest the possibility of application in various industrial fields such as electronics, automobiles, and medical devices.

Hydrogen has a wide flammability range and rapidly diffuses in air, making precision detection technology essential to prevent explosion risks and ensure system safety as the adoption of hydrogen infrastructure expands. Polymer materials are employed in such infrastructure to seal high-pressure hydrogen, and reliable measurement techniques capable of quantifying trace amounts of hydrogen permeating or leaking through these materials is necessary. In this study, a hydrogen quantification system combining volumetric analysis with image analysis was utilized to evaluate the hydrogen uptake and diffusivity of HDPE (high-density polyethylene), NBR (nitrile butadiene rubber), and EPDM (ethylene propylene diene monomer) under high-pressure conditions. The results indicated that HDPE and NBR samples containing silica filler exhibited hydrogen uptake behavior consistent with Henry’s law, while EPDM samples with carbon black filler demonstrated additional hydrogen adsorption on the carbon black surface. These research results provide a foundation for more precisely evaluating the permeation and leakage behavior of polymers in high-pressure hydrogen environments, and are expected to contribute to the safe and efficient development of hydrogen infrastructure.

Gas sensors play a crucial role in monitoring harmful gas concentrations and air quality in real-time, ensuring safety and protecting health in both environmental and industrial settings. Additionally, they are essential in various applications for energy efficiency and environmental protection. As the demand for hydrogen refueling stations and hydrogen fuel cell vehicles increases with the growth of the hydrogen economy, accurate gas concentration measurement technology is increasingly necessary given hydrogen's wide explosion range. To ensure safety and efficiency, gas sensors must accurately detect a wide range of gas concentrations in real-world environments. This study presents two types of gas sensors with high sensitivity, stability, low cost, fast response time, and compact design. These sensors, based on volume and pressure analysis principles, can measure gas filling amounts, solubility, diffusivity, and the leakage of hydrogen, helium, nitrogen, and argon gases in high-density polyethylene charged under high-pressure conditions. Performance evaluation shows that the two sensors have a stability of 0.2 %, a resolution of 0.12 wt･ppm, and can measure gas concentrations ranging from 0.1 wt･ppm to 1400 wt･ ppm within one second. Moreover, the sensitivity, resolution, and measurement range of the sensors are adjustable. Measurements obtained from these sensors of gas filling amounts and the diffusivity of four gases showed consistent results within uncertainty limits. This system, capable of real-time gas detection and characterization, is applicable to hydrogen infrastructure facilities and is expected to contribute to the establishment of a safe hydrogen society in the future.

본 연구는 조현병으로 진단된 환자들과 정상 대조군 간의 자기공명영상을 사용하여 대뇌 피질 하부 영역의 부피를 측정 하여 대뇌의 구조적 이상을 비교하였다. 자기공명영상 검사 후 획득된 3D T1-MPRAGE 영상과 FreeSurfer 소프트웨어 를 사용하여 대뇌 피질 하의 31개 영역의 부피를 측정하였다. 연구 결과는 조현병 환자군에서 양측 측뇌실, 양측 맥락얼기, 제3뇌실, 뇌척수액 영역의 부피가 정상 대조군보다 유의하게 증가했으며, 좌 우반구 피질, 좌측 시상, 좌측 해마 영역의 부피는 정상 대조군보다 유의하게 감소하였다. 또한, 측정된 대뇌의 부피값과 PANSS 총점수는 약한 음의 상관관계를 나타 내었다. 따라서, 본 연구에서는 자기공명영상과 FreeSurfer를 이용하여 조현병 환자의 대뇌 피질 하 부피를 측정하고 이를 정상 대조군과 비교하여 유의한 증가와 감소를 확인하였다.

PURPOSES : The aim of this study is to evaluate the effects of air voids, binder content, and aggregate gradation on the indirect tensile strength (IDT) and cracking tolerance index (CTindex) of cored asphalt pavements. METHODS : Cored samples were obtained from roads in Incheon city, and several laboratory experiments were performed. First, the cored samples were first to cut into a size appropriate for the IDT test. Subsequently, the air voids of the samples were measured. The damaged sample from the IDT test was loose mixed at 150 ℃ before the binder content was determined, which was conducted via an asphalt extraction test. Finally, the clean aggregates obtained from asphalt extraction process were analyzed in the aggregate gradation test. RESULTS : The result shows that an increase in air voids from 4% to 8% decreases the IDT and cracking tolerance index (CTindex) by 30% and 28%, respectively. Incorporating a binder enhances the ductile behavior of the asphalt mixture, resulting in a higher CTindex. Finally, the contribution of the aggregate grade on the IDT and CTindex is negligible. CONCLUSIONS : The IDT and CTindex are primarily affected by the air voids and binder content. A higher percentage of air voids results in a lower IDT. In addition, a higher amount of binder increases the IDT and CTindex of the cored samples. Meanwhile, the aggregate grade does not affect the IDT.

분리막 기반 공정은 기존 공정에 비해 에너지 소비 및 환경 영향을 감소시킬 수 있는 잠재력을 갖고 있다. 분리막 공정의 성능은 분리막의 투과 특성과 직결되기 때문에, 선택도와 투과도가 우수한 새로운 분리막 소재를 개발하기 위해 많은 연구가 진행되어 왔다. 본 연구에서는 기체 투과선택성 향상을 위해 부피가 큰 에틸 치환기를 포함하는 diamine 단량체인 4,4’-methylenebis(2,6-diethylaniline) (MDEA)을 도입한 폴리이미드를 합성한 후 그 특성을 관찰하고 기체 투과 특성을 조사하 였다. 이미드링 질소의 오쏘에 위치한 에틸기는 고분자 사슬의 패킹을 방해하고 사슬 강성과 고분자 사슬 간 거리를 증가시켰 다. MDEA 기반 폴리이미드 분리막의 기체 투과 특성을 조사한 결과, 프로필렌/프로판 선택도 14.5와 프로필렌 투과도 7.0 barrer의 결과를 얻었다. 부피가 큰 치환기로 인해 기체 확산 길이가 증가하여 기체 투과 선택성이 높아졌음을 확인하였다. 혼 합 기체 투과 결과 또한 MDEA 기반 폴리이미드 분리막이 실제 혼합 기체 공정에서 높은 선택도를 달성할 수 있다는 것을 보 여준다. 이러한 MDEA 기반 폴리이미드는 우수한 투과도 및 선택도로 경제적인 프로필렌 분리의 가능성을 크게 높일 수 있다.

폴리옥시에틸렌(POE) 계열에서 두 번째로 작은 화합물인 양친매 분자 2-(2-hexyloxyethoxy) ethanol (C6E2) 수용액의 밀도를 측정하였다. 밀도 측정은 진통 튜브 밀도계를 이용하여 279.15 K와 282.15 K에서 이루어졌다. 측정된 밀도로부터 2성분 계 C6E2 (1)/H2O (2)의 과잉 부피와 부분 몰 부피를 결정하였다. 과잉 부피는 음의 편차를 나타내었으며, C6E2의 몰 분율 χ ≃ 0.45에서 최소 값을 나타내었다.  C6E2 와 물 분자 사이에 끌어당기는 작용이 상대적으로 우월하지만, χ ≃ 0.45 에서 이 작용이 가장 크다는 사실을 말해준다. 2성분 계 C6E2 (1)/H2O (2)에서 부분 몰 부피 V1 는 몰 분율 χ 에 따라서 단조 증가하였으며, V2 는 감소하였다. V1 과 V2 에서 C6E2 분자들의 회합을 암시하는 특이점은 관찰되지 않았다.

The gas adsorption isotherm requires accurate measurement for the analysis of porous materials and is used as an index of surface area, pore distribution, and adsorption amount of gas. Basically, adsorption isotherms of porous materials are measured conventionally at 77K and 87K using liquid nitrogen and liquid argon. The cold volume calibration in this conventional method is done simply by splitting a sample cell into two zones (cold and warm volumes) by controlling the level sensor in a Dewar filled with liquid nitrogen or argon. As a result, BET measurement for textural properties is mainly limited to liquefied gases (i.e. N2 or Ar) at atmospheric pressure. In order to independently investigate other gases (e.g. hydrogen isotopes) at cryogenic temperature, a novel temperature control system in the sample cell is required, and consequently cold volume calibration at various temperatures becomes more important. In this study, a cryocooler system is installed in a commercially available BET device to control the sample cell temperature, and the automated cold volume calibration method of temperature variation is introduced. This developed calibration method presents a reliable and reproducible method of cryogenic measurement for hydrogen isotope separation in porous materials, and also provides large flexibility for evaluating various other gases at various temperature.

Two emitting compounds, 9,10-bis-[1,1;3,1]terphenyl-5-yl-1,5-di-o-tolyl- anthracene [TP-DTA-TP] and 9,10-bis-phenyl[1,1;3,1]triphenyl-5-yl-1,5-di-o- tolylanthracene[ TPB-DTA-TPB] based on newtwisted core moiety were synthesized through boration, Suzuki reaction, and Sandmeyer reactions. EL performance was improved by varying the chemical structure of the side group. Physical properties such as optical, electrochemical, and electroluminescent properties were investigated. Synthesized compounds were used as an EML in OLED device: ITO/2-TNATA (60 nm)/NPB (15 nm)/TP-DTA-TP or TPB-DTA-TPB (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). It was found that TPB-DTA-TPB showed higher luminance efficiency and better C.I.E. value than TP-DTA-TP device.

석유제품은 다양한 형태의 탄화수소화합물로 구성되어진 화합물로, 다른 종류의 액체류와 마찬가지로 온도변화에 따른 밀도와 부피의 변화가 발생한다. 액상에서 석유제품의 밀도를 측정하는 방법은 분별 증류된 각 석유제품에 대해 주로 얻어진 실험 데이터를 기반으로 한다. 본 연구에서는 등유와 자동차용 경유의 온도변화에 따른 밀도와 부피변화를 실제 측정하여 온도변화에 따른 변화추이를 분석하고, 국제규격인 ASTM에서 제시하는 밀도부피 환산표를 이용한 환산값을 계산하고 두 값을 비교분석하였다. 또한, 국내 계량 관련법에서 규정하고 있는 온도변화에 대한 기준과 실측값과의 상호 비교를 통해 차이점을 분석하였다.

콘크리트 포장의 내구성 저하는 포장체의 파손뿐만 아니라 사용자의 주행성에도 영향을 주며, 또한 유지관리 비용을 증가시키는 등 복합적 문제를 초래한다. 이러한 콘크리트 내구성 문제를 개선하기 위한 방안으로 콘크리트의 내부양생(internal curing)에 대한 관심이 고조되고 있다. 내부양생은 표면 살수나 피막양생제를 도포하는 기존의 양생 방식과는 달리 콘크리트 배합 시 수분공급 물질을 혼입하여 내부로부터 수분을 공급하는 기법으로, 양생효율을 현저히 증진시켜 역학적 특성, 투수 및 균열 저항성, 부피안정성 등 콘크리트의 다양한 성능을 향상시키는 것으로 잘 알려져 있다. 특히 포장용 콘크리트 배합과 같이 광물성혼화재(SCMs)를 포함하는 경우, 소요성능의 발현을 위해서는 철저한 양생이 무엇보다 중요하다. 이에 착안하여 본 연구에서는 최근 콘크리트의 내부양생 재료로서 각광을 받고 있는 고흡수성폴리머(SAP)를 적용한 모르타르의 강도 및 부피변화 특성을 파악하여 콘크리트 포장에의 적용 가능성을 평가하였다. 이를 위하여 가교밀도와 평균 입자크기가 다른 4종의 폴라아크릴산나트륨 SAP를 혼입한 모르타르를 제작하고 SAP 함량 및 종류별 강도 발현, 자기수축 및 내부 상대습도 거동 특성을 측정하였다.

In this study, factors analysis is performed for reducing friction in elevation motion of a large television stand over 50 inch. The first study is for specification decision and volume compensation experiment as an apparatus for compensating of the volume of the cylinder is compressed as the volume of piston rod. The second study is for optimized piston structure development by comparison pipe orifice and labyrinth orifice. Consequently, the result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod ∅8 x ∅4 and riveting system. and the labyrinth orifice is not founded that of the Ø0.4~0.6 orifice both tests on 300 mm intervals.

Isosteric heat of hydrogen adsorption is one of the most important parameters required to describe solid-state hydrogen storage systems. Typically, it is calculated from adsorption isotherms measured at 77K (liquid N2) and 87K (liquid Ar). This simple calculation, however, results in a high degree of uncertainty due to the small temperature range. Therefore, the original Sievert type setup is upgraded using a heating and cooling device to regulate the wide sample temperature. This upgraded setup allows a wide temperature range for isotherms (77K ~ 117K) providing a minimized uncertainty (error) of measurement for adsorption enthalpy calculation and yielding reliable results. To this end, we measure the isosteric heats of hydrogen adsorption of two prototypical samples: activated carbon and metal-organic frameworks (e.g. MIL-53), and compared the small temperature range (77~87K) to the wide one (77K ~ 117K).

In this study, The first study attempted to reduce the frictional force the gas seal lip technology. The second study is for specification decision and volume compensation experiment as an apparatus for compensating of the volume of the cylinder is compressed as the volume of piston rod. Consequently, in the gas seal lip technology, the outer-in diameter of ∅20 x ∅8 in the test result of hollow rod is revealed more proper if the weight of 50 inch television assumed as 30 kg. and the result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod ∅8 x ∅4 and riveting system. The spring constant(K) showed an excellent value above the target value of 0.01 to 0.015 N/mm.

In this study, factors analysis is performed for reducing friction in elevation motion of a large television stand over 50-inch. The first is a pipe type cross-section control for accurate position control of the piston rod. Here it was compared with the pipe type and labyrinth type orifice cross-section. The second study is for specification decision and volume compensation experiment as an apparatus for compensating of the volume of the cylinder is compressed as the volume of piston rod. Consequently, in the orifice cross section study between pipe type and labyrinth type through CAE and experimental consideration, cross section of labyrinth type orifice is preferred for reducing of friction. The result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod φ8×φ4 and riveting system.

In olefin/paraffin separation process, new technology such as membrane separation process has been ever demanding for both economic and environmental reasons. facilitated olefin transport membrane, containing positively charged silver nanoparticles (Ag NPs) by electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) as olefin carriers dispersed in poly(vinyl pyrrolidone) (PVP), shows extremely high separation performance for propylene/propane mixtures. However, higher permeance is always demanding for practical applications. In this study, POSSs were added to PVP/Ag NPs/TCNQ membranes. Among various kinds of POSS, trisilanolisooctyl POSS showed higher permeance with a moderate selectivity. Therefore it is concluded that mesoporous POSS is an effective additive in improving the gas permeance.

In this paper, we present the result of investigations pertaining to the elastic buckling of simply supported columns with various cross-sectional dimensions but the same length and volume. In the investigations the accuracy of the analysis methods is studied and it was found that the result obtained by the successive approximations technique is the most accurate. In addition, the elastic buckling loads of columns with variable cross-section dimensions are obtained by the theoretical and numerical methods. From the results, it was found that the buckling loads obtained by the numerical methods are close to the buckling loads obtained by the successive approximations technique for the practical standpoints. Moreover, the buckling load of column with convexity in its middle is the highest while the buckling load of the tapered column is the lowest as expected.

By controlling the piston speed of the gas spring applying to the digital television stand application of the gas spring, a user can operate the elevation when the gas spring is working under long stroke(200～300 mm, the TV elevation displacement). According to stroke, by some devices with the problem rising from between the difference of external forces, the emotional quality in television elevational function is realized. The piston speed control technique is investigated to perform this experiment piston flow analysis and flow rate control for precise tubular cross section and propose a piston structure for elevation action. This study is for the development of the gas spring of the large size television stand with 50 inch over. In the gas spring development of elevation working, a device to compensate for the volume of the cylinder is generated as much the volume of the piston rod. As this study result, at the development of working gas spring, the hollow shaft is more favorable than the solid one in the apparatus to compensate for the cylinder volume generated.