In this study, we report the microstructural evolution and shear strength of an Sn-Sb alloy, used for die attach process as a solder layer of backside metal (BSM). The Sb content in the binary system was less than 1 at%. A chip with the Sn-Sb BSM was attached to a Ag plated Cu lead frame. The microstructure evolution was investigated after die bonding at 330 °C, die bonding and isothermal heat treatment at 330 °C for 5 min and wire bonding at 260 °C, respectively. At the interface between the chip and lead frame, Ni3Sn4 and Ag3Sn intermetallic compounds (IMCs) layers and pure Sn regions were confirmed after die bonding. When the isothermal heat treatment is conducted, pure Sn regions disappear at the interface because the Sn is consumed to form Ni3Sn4 and Ag3Sn IMCs. After the wire bonding process, the interface is composed of Ni3Sn4, Ag3Sn and (Ag,Cu)3Sn IMCs. The Sn-Sb BSM had a high maximum shear strength of 78.2 MPa, which is higher than the required specification of 6.2 MPa. In addition, it showed good wetting flow.

Plastics are widely used in industries in human society and because of their structural stability, degradation is a serious global issue. To estimate the degradation of plastic, 31 edible mushrooms were cultured with the selected plastic films (polyethylene [PE], polystyrene [PS], and poly(ethylene terephthalate) [PET]) for 3 months at 25 °C. Measuring the weight of the films showed that four species of mushrooms, namely Porostereum spadiceum, Ganoderma lucidum, Coprinellus micaceus, and Pleurotus ostreatus, exhibited the highest degrees of plastic degradation. In addition, the mushrooms and fungi that exhibited the most significant plastic degradation were cross-cultured to promote this degradation. As a result, cross-cultivation of G. lucidum and Aspergillus niger showed a weight loss of 2.49% for the PET film. For the PS film, Aspergillus nidulans showed a weight loss of 4.06%. Cross-cultivation of A. nidulans and C. micaceus, which showed a weight loss of 2.95%, was noted as an alternative for PS biodegradation, but is harmful to humans. These bio-degradation effects of edible mushroom will contribute to the development of alternatives for eco-friendly plastic degradation.

As a member of ectomycorrhizal fungi, Tricholoma matsutake has a symbiotic relationship with its host, Pinus densiflora. To cultivate T. matsutake artificially, the co-cultivation of T. matsutake mycelia and bacteria from shiro was introduced. In this study, bacteria were isolated from soil samples in Bonghwa-gun, and seven bacterial isolates (B22_7_B05, B22_7_B06, B22_7_B07, B22_7_B08, B22_7_B10, B22_7_B13, and B22_7_B14) promoted the growth of T. matsutake mycelia (147.48, 232.11, 266.72, 211.43, 175.17, 154.62, and 177.92%, respectively). Sequencing of the 16S rRNA region of the isolated bacteria was performed. B22_7_B05 and B22_7_B10 were identified as Bacillus toyonensis, B22_7_B06 and B22_7_B08 as Paenibacillus taichungensis, B22_7_B07 and B22_7_B14 as P. gorilla, and B22_7_B13 as P. odorifer. These bacterial isolates were associated with the shiro community and are expected to contribute to the cultivation of T. matsutake.

Tricholoma matsutake is a traditional favorite food in East Asia, cultivated in fairy rings called “shiro,” which are found near Pinus densiflora. For effective artificial cultivation of Tri. matsutake, microorganisms from symbiotic fairy rings are co-cultivated. In this study, one bacterial isolate (Y22_B35) and two fungal isolates (Y22_F64 and Y22_F68) displayed growth-promoting effects on Tri. matsutake mycelium (158.47, 125.00, and 122.26% enhanced growth, respectively). For identification, 16S rRNA or ITS regions from the microorganisms¡¯ genomes were sequenced. Other sequences, including BenA, CaM, and RPB2 were sequenced in the fungal isolates. The bacterial isolate Y22_B35 was identified as Bacillus cereus. Y22_F64 and Y22_F68 were identified as Umbelopsis nana and Aspergillus parvulus, respectively. To identify the effects of the dominant microorganisms on Tri. Matsutake cultivation, metagenomic analyses were performed. Discovery of these Tri. matsutake mycelium growth-promoting microorganisms and metagenomics analyses are expected to contribute to our understanding of Tri. matsutake fruiting body growth and construction of biomimicry.

In this study, the expression of genes related to fruit ripening was investigated using realtime PCR. The study aimed to determine the effective conditions of calcium compounds (Calcium citrate, calcium chloride, calcium nitrate, GH-Ca, OS-Ca) and chitosan treatment to extend the shelf-life in the ‘Kumhong’ nectarine and ‘Madoka’ peach fruits. In this study, in the ‘Kumhong’ and ‘Madoka’ fruits, the expression of genes related to cell wall degradation, pectin lyase (PL), polygalacturonase (PG), and pectin methylesterase (PME), was inhibited by calcium, chitosan, or a mixture (Chitosan+CaCl2) treatment. In ‘Madoka’ peach, although the expression of the PG gene was suppressed at pre-harvest Ca and chitosan treatment, the expression of the PL gene was induced at pre- and post-harvest Ca and chitosan treatment compared to the control. The spray of calcium, chitosan itself, or a mixture (Chitosan+ CaCl2) on the trees at the ripening stage and harvested fruits can extend the shelf-life by suppressing the expression of cell wall degrading enzymes genes (PL, PG, PME) in ‘Kumhong’ nectarine and ‘Madoka’ peach tree. These results provide valuable information for the development of technology for the extension of the shelf-life of peach and nectarine fruits.

This study addresses the environmental impact associated with waste management and natural aggregate production. It explores the potential of utilizing Coal Bottom Ash (CBA) and Reclaimed Asphalt Pavement Aggregate (RAPA) as complete replacements, respectively, for fine and coarse aggregates in concrete. Despite their similarities to natural aggregates, CBA and RAPA often end up in landfills. Laboratory tests were conducted, revealing satisfactory performance in drying shrinkage and air void parameters. However, while the flexural strength met design requirements, the compressive and splitting tensile strengths were lower than predicted. The deviation in strength development behavior from natural aggregate concrete (NAC) was attributed to weak agglomerated aggregates in RAPA and the large size of the interfacial transition zone (ITZ) due to the old asphalt coating surrounding RAPA. To enhance the strength behavior, two methods were employed: compaction in the form of roller-compacted concrete and RAPA abrasion carried out by rolling RAPA in a concrete mixer. Compaction improved aggregate interlock, while RAPA abrasion decreased agglomerated aggregates and minimized asphalt coating, reducing ITZ size. These treatments resulted in improvements in compressive, flexural, and splitting tensile strengths, with the combination of both treatments having the most significant effect. Analysis of relationships between flexural, splitting tensile, and compressive strengths indicated that CBA and RAPA concrete behaved more similarly to NAC after the treatments. This research suggests that with appropriate interventions, it is feasible to utilize CBA and RAPA in concrete, contributing to sustainable construction through improved waste management, carbon footprint reduction, and conservation of natural resources.

대한민국의 도로의 증가로 인한 복잡화에 따라 터널의 수와 연장이 지속적으로 증가하고 있다. 본 연구는 시멘트콘크리트 포장의 성 능과 수명에 미치는 환경조건의 영향을 분석한다. 현재까지 시공된 고속도로의 많은 부분이 시멘트콘크리트 포장으로 되어 있으며, 이 에 대한 연구는 오랫동안 진행되어 왔다. 부등건조수축은 슬래브의 상하부 온습도 차이에 의해 발생하며, 일일 및 계절적 주기에 따라 발생한다. 일반적으로, 온습도 변화에 따라 컬링이나 와핑이 발생하는데, 컬링은 낮에는 높은 온도로 인한 하향 수축, 밤에는 낮은 온 도로 인한 상향 수축을 나타낸다. 그러나, 환경조건 변화에 따른 콘크리트 내부 습도 변화에 대한 이해는 아직 크게 연구가 진행되지 않아 포장 설계에 적절히 반영되지 못하고 있다. 이러한 연구는 터널 등 배수가 어려운 지역에서 콘크리트포장의 적절성을 판단하여 공용수명에 기여할 것으로 예상한다. 본 연구에서는 슬래브의 하부 조건이 콘크리트 내부 습도에 미치는 영향을 실험적으로 조사한다. 콘크리트 시편을 제작하여 특수한 환경조건에서의 습윤 차이를 모사하여 수분 이동 특성을 연구한다. 실험에서는 슬래브의 한쪽면을 고정하고 반대편이 부등건조수축으 로 인해 발생하는 변형률과 수직변위를 측정할 장비를 설치하여 시간에 따른 변화량을 확인한다.

Acknowledging the limited opportunities faced by learners of Korean in the US, this study investigates the efficacy and challenges of immersive Korean language-focus residential programs in US college dormitories. Through an examination of a Korean language dormitory (called K-house) at a Midwestern university in the US, the current study sheds light on the optimal experiences and effective immersive environments that college langauge dormitory programs in the US can foster for both linguistic and cultural learning of Korean. By delving deeper into the specific programming and experiences of K-house residents, the study demonstrates that K-house facilitates access to Korean language and culture, enhances motivation of Korean language study, and cultivates a sense of belonging to the K-house community among K-house residents. Additionally, the findings of this study provide valuable insights for designing effective Korean language dormitory programs that promote language and cultural immersion in the context of teaching and learning Korean as a foreign language. Furthermore, this study offers suggestions for future research in this area.

In this study, we proposed a novel concept of liquid level indicator that can stably measure the liquid level even with changes in liquid density by enormous temperature changes. This uses a distributed optical fiber sensor based on Rayleigh scattering with high spatial resolution. Additionally, taking advantage of the flexibility of an optical fiber sensor, we introduced a bendable supporting structure and made it possible to freely adjust the angle for ease of installation of the liquid level indicator. In the proof-of-concept experiment using a prototype incorporating the proposed concept, we confirmed that the interface location can be effectively detected by utilizing the difference in heat transfer characteristics between liquid and gas phases, demonstrating the feasibility of liquid level measurement. Such a liquid level indicator is expected to enable more accurate level measurements in environments with huge temperature changes and to be conveniently used even in situations where installation and maintenance of the level meter are challenging due to complex internal structures.

본 연구는 오픈소스 라이브러리인 OpenCV를 활용해 다양 한 시설과채류의 표현형 분석에 적용 가능한 컴퓨터 비전 기 술을 탐구하였다. 토마토에 대해서는 이미지의 색상을 분석 하여 숙성도를 판정하며, support vector machine(SVM) and histogram of oriented gradients 기법을 통해 숙성된 토마토 를 효과적으로 검출하였다. 파프리카의 경우, 색상 분포를 시 각화한 후, 가우스 혼합 모델로 클러스터링을 실행하여 수확 파프리카의 색상 특성을 분석하였다. 네트 멜론의 품질 평가 에서는 LAB 색상 공간, 이진화 이미지 및 깊이 매핑을 활용하 여 멜론의 네트 패턴을 정량화하였다. 추가로, 오이 온실에서 화방 검출을 위해 깊이 정보와 색상 정보를 조합하여 다양한 크기와 거리의 화방을 성공적으로 검출하였다. 이 연구의 결 과로, 해당 컴퓨터 비전 기술들이 시설과채류의 생장 모니터 링, 숙성 및 품질 평가 등에서의 유효성을 확인하였다. 농산업 에서 컴퓨터 비전의 효과적 적용을 위해, 후속 연구자나 개발 자들이 재배 생리와 연관된 지표를 기반으로 이 기술들을 보 완할 경우, 실제 농업 현장 및 연구에서 널리 활용될 가능성이 크다.

Gastrodia elata has been used in traditional Chinese medicine for treating headaches, dizziness, and convulsive illness for centuries. G. elata has traditionally been processed by steaming or blanching to increase the content and quality of its main ingredients. This study aimed to identify changes in physicochemical properties and active ingredients of G. elata depending on the steaming time. Data of this study could be used to develop traditional medicine and health foods. No steaming was used as a control. Steaming time was 5, 10, 20, 30, 60, or 120 min. The drying yield according to the steaming time ranged from 20.2% to 22.9%, with the lowest drying yield at 120 min. As the steaming time increased, gastrodin content increased more than that in fresh G. elata due to inhibition of β-glucosidase enzyme activity, 4-hydroxybenzyl alcohol condensation, and parishin decomposition. Steamed G. elata did not show higher total polyphenols, total flavonoids, or ABTS radical scavenging activities than fresh G. elata even with an increase of steaming time. The steaming time to improve the quality of G. elata may varied depending on the size of G. elata. Thus, it is important to set the steaming time taking these characteristics into consideration.

Friction stir spot welding (FSSW) is a solid-state joining process and a rapidly growing dissimilar material welding technology for joining metallic alloys in the automotive industry. Welding tool shape and process conditions must be appropriately controlled to obtain high bonding characteristics. In this study, FSSW is performed on dissimilar materials AA5052-H32 aluminum alloy sheet and SPRC440 steel sheet, and the influence of the shape of joining tool and tool insertion depth during joining is investigated. A new intermetallic compound is produced at the aluminum and steel sheets joint. When the insertion depth of the tool is insufficient, the intermetallic compound between the two sheets did not form uniformly. As the insertion depth increased, the intermetallic compound layer become uniform and continuous. The joint specimen shows higher values of tensile shear load as the diameter and insertion depth of the tool increase. This shows that the uniform formation of the intermetallic compound strengthens the bonding force between the joining specimens and increases the tensile shear load.

한국 남해 동부 해역인 통영해역에 설치된 연안 수온 분석 결과, 태풍이 남해안에 상륙하기 전에 수온이 급격하게 상승한 것으 로 나타났다. 수온 상승은 표층(5m)은 물론 저층(15m)까지 같이 발생하였다. NOAA 위성에서 관측한 표면수온자료 분석 결과, 태풍이 상 륙하기 전 한국 남해 동부 해역의 동쪽 해역에 30℃의 수온을 가지는 해수가 존재하였다. 한국 남동해역은 대마난류에 의해 서쪽에서 동 쪽으로 해류가 우세한 지역이나 위성 자료 분석 결과, 30℃의 해수는 동쪽에서 서쪽으로 이동한 것으로 나타나 태풍 상륙 전에 태풍에 의 한 에크만 수송의 영향을 받은 것으로 나타났다. 또한 남해 동부 해역은 한국 동해 해역과 달리 수심이 깊지 않기 때문에 바람에 의한 연 직 혼합으로 인해 전 수층의 수온이 일정하게 나타날 수 있다. 수층별 수온 상승이 같은 날에 발생하였기 때문에 저층 수온 상승은 연직 혼합에 의한 결과라 볼 수 있다. 따라서 한국 남동해역은 태풍의 접근 방향과 고수온의 형성 위치에 따라 에크만 수송에 의해 수온이 급 상승할 수 있는 해역임을 알 수 있다.

Fluorine-doped tin oxide (FTO) has been used as a representative transparent conductive oxide (TCO) in various optoelectronic applications, including light emitting diodes, solar cells, photo-detectors, and electrochromic devices. The FTO plays an important role in providing electron transfer between active layers and external circuits while maintaining high transmittance in the devices. Herein, we report the effects of substrate rotation speed on the electrical and optical properties of FTO films during ultrasonic spray pyrolysis deposition (USPD). The substrate rotation speeds were adjusted to 2, 6, 10, and 14 rpm. As the substrate rotation speed increased from 2 to 14 rpm, the FTO films exhibited different film morphologies, including crystallite size, surface roughness, crystal texture, and film thickness. This FTO film engineering can be attributed to the variable nucleation and growth behaviors of FTO crystallites according to substrate rotation speeds during USPD. Among the FTO films with different substrate rotation speeds, the FTO film fabricated at 6 rpm showed the best optimized TCO characteristics when considering both electrical (sheet resistance of 13.73 Ω/□) and optical (average transmittance of 86.76 % at 400~700 nm) properties with a figure of merit (0.018 Ω-1).

고등학생의 시기에서는 대인관계가 매우 중요한 역할을 수행한다. 하지만, 불안정한 대인관계는 심리정서적 문제를 유발하는 등 부정적 문제를 유발할 수 있다. 대인관계에 있어 심리정서적 측면을 남성 보다 더 고려하는 여자 고등학생들의 특성에 기초하여 이러한 문제는 두드러질 수 있다. 본 연구는 여자 고등학생들의 대인관계의 질이 스마트폰 과의존에 영향을 미치는지 분석 하는데 목적이 있다. 연구대상은 J시 W고등학교에 재학 중인 여자 고등학생 53명이다. 대인관계의 질은 Korean ver. of Friendship Quality Questionnaire를 활용하여 조사하였다. 대인관계의 질은 21문항이며, 5점 척도로 점수가 높으면 높을수록 대인관계의 질이 높음을 의미한다. 스마트폰 과의존은 스마트폰 과의존 척도를 활용하여 조사하였다. 스마 트폰 과의존은 10문항이며, 4점 척도로 점수가 높으면 스마트폰 과의존 수준이 높음을 의미한다. 그 결과, 대인관계의 질이 스마트폰 과의존에 부적 (-) 영향을 미치는 것으로 나타났다. 이러한 결과는 대인관계의 질이 높아질수록 스마트폰 과의존 수준이 저하된다고 설명할 수 있다. 이에 기초하여, 여자 고등학생들의 대인관계, 스마트폰 사용과 관련한 교육과 접근에 있어서 이러한 결과를 고려해야 할 것이며, 대인관계를 향상시킬 수 있는 접근이 필요할 것이다. 후속 연구들에서는 대상의 범위를 확대하여 다양한 대상군들과 비교 분석할 필요가 있으며, 스마트폰 과의존과 대인관계의 질의 관계에 있어서 영향을 미칠 수 있는 다양 한 변수들을 고려한 심층 분석연구들이 수행되어야 할 것이다.

When cooking, especially during processes such as grilling or frying, harmful gases are generated. Among them, fine dust is a major factor causing lung cancer, and to eliminate it, range hoods are commonly used. Particularly, when using portable cooking device like gas stoves, it is even more challenging to remove fine dust. In this study, a cooking device was developed to combine steam and cooled air in the air-curtain area to recover fine dust generated during the cooking process, allowing it to be collected as food. The device was evaluated according to criteria defined independently and validated through experiments. As a result, all criteria were satisfied within the specified range.

With the mandatory implementation of ESC for trucks starting in 2023, domestic truck manufacturers in South Korea are advocating for a relaxation of the maximum safe slope angle to achieve cost savings. However, there is a lack of research on the dynamic safety of trucks based on ESC installation and the relaxation of the maximum safe slope angle. This study evaluates the relationship between static safety factor (SSF) and the maximum safe slope angle, analyzing the dynamic stability of trucks through simulation considering various experimental variables. The results quantitatively demonstrate the impact of relaxing the maximum safe slope angle on dynamic safety and provide recommendations for future safety regulations.

OWEC(Overtopping Wave Energy Converter)는 월파된 파도를 이용한 파력발전시스템이라한다. OWEC의 성능 및 안전성은 파고, 주기 등 파도의 특성에 의해 영향을 받는다. 따라서 해역 특성에 따른 OWEC의 최적 형상과 구조안전성에 관한 연구가 필요하다. 본 연구 에서는 울릉읍 연안 해양 환경 데이터를 이용하였으며, SPH(Smoothed Particle Hydrodynamics) 입자법 해석을 통해 기존 케이슨 하부 구조에 변화를 준 모델 4개를 비교하여 월파 효율을 분석하였다. 그 결과, 하부 구조의 변경 및 경량화가 가능함을 확인하였다. 최적화 해석을 통 해 설계 하중에 내하력을 가지는 하부 구조인 새로운 트러스형 구조를 제안하였다. 이후 부재 직경 및 두께를 설계변수로 하는 사례 연구 를 통해 허용응력조건 하에서 구조 안전성의 확보를 확인하였다. 주기적인 파랑 하중을 받기 때문에 제안하는 구조의 고유 진동수와 해 당 해역의 파주기를 비교하였으며, 1년 재현 주기의 파랑을 하중으로 한 조화응답해석을 수행하였다. 제안하는 하부 구조는 동일 가진력 에서 기존 설계 대비 응답의 크기가 감소하였으며, 기존 대비 32% 이상의 중량 절감을 수행하였다.

The aim of this study was to analyze the design characteristics of Chinese fashion designer Feng Chen Wang and interpret their implicit meaning from a neo-deconstruction perspective. A review of domestic and foreign literature, outlined the development of deconstruction and neo-deconstruction, with neo-deconstruction’s aesthetic features termed ‘traditional fusion’, ‘positive playfulness’, ‘open communication’, and ‘multiple inclusiveness’. These features informed an analysis of Feng Chen Wang’s fashion design. Four key findings emerged. First, ‘traditional fusion’ combines traditional Chinese colors, items, handicrafts, and patterns with modern design to break down boundaries between past and modern, tradition and fashion. Second, ‘positive playfulness’ promotes creativity and fun, using bright colors, exaggerated accessories, and playing withthe composition of traditional clothes to create a positive atmosphere. Third, ‘open communication’ emphasizes design that combines practicality and creativity in response to consumer needs, incorporating the thoughts arising from individual experiences and interest in social phenomena. Fourth, ‘multiple inclusiveness’ breaks down boundaries of sexuality, hierarchy, and body shape, embracing various ideas of beauty and respecting uniqueness through design that are seen as available to all. Using a neo-deconstruction perspective, Feng Chen Wang provides novel product planning ideas for Chinese fashion brands and reflects the values and meaning of modern design pursued by contemporary Chinese designers.

This study was performed to investigate antioxidant and anti-inflammatory activities of perilla(Perilla frutescens L.) seed, flower and leaf according to extraction condition. Perilla seed extracts(PSE), perilla flower extracts(PFE), perilla leaf extracts(PLE) was extracted by stirring extraction (STE, 25°C), shaking extraction (SHE, 80°C), and sonication assisted extraction(SAE, , 25°C) with 94% ethanol, 60% ethanol and distilled water, followed by analysis of total polyphenol and flavonoid and testing radical scavenging activities. The highest total polyphenol content (5.47, 9.36, 38.58 mg gallic acid equivalent/g), total flavonoid content(5.77, 8.62, 46.44 mg catechin equivalent/g), ABTS(10.68, 19.46, 63.56 mg trolox equivalent/g) and DPPH(6.51, 7.69, 79.73 mg trolox equivalent/g) radical scavenging activity of PSE, PFE and PLE was observed in the HWE with 60% ethanol,. Among the three extraction method, SHE provided the best results for yield, polyphenol, flavonoid content of perilla seed, flower, leaf in comparison to STE or SAE. SHE with 60% ethanol of perilla seed, flower, leaf more effectively inhibited secretion of nitric oxide(NO) and pro-inflammatory cytokine in RAW 264.7 macrophage exposed to LPS compared to other extraction solvent and method. Therefore, these extracts obtained from perilla seed, flower, leaf could be used antioxidant and anti-inflammatory ingredients in the food industry.